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The Metrics International System of Units

Area Conversion Factors
Force Conversion Factors
Hard Conversions for Construction Materials
Length Conversion Factors
Mass Conversion Factors
Pavement Marking Coverage Chart
Pipe Conversion Factors
Plate Conversion Factors
Power Conversion Factors
Pressure or Stress Conversion Factors
Reinforcing Steel Conversion Factors
Sheet Metal Conversion Factors
Sieve Conversion Factors
Symbols
Temperature Conversion Factors
Trades in Construction
Useful Conversion Factors
Volume Conversion Factors
Wire Conversion Factors

 

Overview

The International System of Units (SI) is a modernized version of the metric system established by international agreement. The metric system of measurement was developed during the French Revolution and was first promoted in the U.S. by Thomas Jefferson. Its use was legalized in the U.S. in 1866. In 1902, proposed congressional legislation requiring the U.S. Government to use the metric system exclusively was defeated by a single vote.

SI provides a logical and interconnected framework for all measurements in science, industry, and commerce. The metric system is much simpler to use than the existing English system since all its units of measurement are divisible by 10.

Conversion Factors

The following list provides the conversion relationship between U.S. customary units and SI (International System ) units. The proper conversion procedure is to multiply the specified value on the left (primarily U.S. customary values) by the conversion factor exactly as given below and then round to the appropriate number of significant digits desired. For example, to convert 11.4 ft to meters: 11.4 X 0.3048 = 3.47472, which rounds to 3.47 meters. Do not round either value before performing the multiplication, as accuracy would be reduced. A complete guide to the SI system and its use can be found in ASTM E 380, Metric Practice.

Foot-Meter Conversion Factors

There is some confusion surrounding the correct value to use when converting the English "foot" measurement to the metric "meter" measurement and vice versa. This confusion stems from the fact that there are two, though slightly different, conversion factors that may be used in this process.

Both values

  • 0.304 800 609 6012

and

  • 0.3048

are correct factors that can be used for converting feet to meters.

How is it possible to have two values for the same conversion? To gain an understanding of how this is possible, and why it is allowed to continue, it is necessary to take a brief look at the history of the metric system within the United States.

History

The metric system was developed during the French Revolution in the late 1700's. It was first promoted in the United States by Thomas Jefferson and in 1866 the US Congress officially recognized the metric system as a legal system of units. In 1893, the Office of Weights and Measures (now the National Bureau of Standards), fixed the value of the U.S. "yard" in terms of the meter as follows:

  • 1 yard = 3600/3937 meter or 1 yard = 0.914 401 8288 meter

this relation is equivalent to:

  • 1 foot = 12/39.37 meter or 1 foot = 0.304 800 609 6012 meter

Unfortunately, other nations used a slightly different conversion factor. To solve this deviation, a refinement was made in the definition of the yard to bring the US yard and the yard used in other countries into agreement. In 1959 the national standards laboratories of the English-speaking nations agreed to standardize the relation between the yard and the meter as follows:

  • 1 yard = 0.9144 meter
  • 1 foot = 0.3048 meter
  • 1 inch = 25.4 millimeter

The new length of yard is shorter by exactly two parts in a million.

At the same time it was decided that any data in feet derived from and published as a result of geodetic surveys within the U.S. would remain with the old standards (1 foot = 12/39.37 meter) pending any further decisions. This foot measurement is called the U.S. Survey foot.

This then, is how we came to have two values for foot-meter conversions. One value, (1 foot = 12/39.37 meter), should be used when converting a measurement that is based on geodetic surveys. The other value, (1 foot = 0.3048 meter), should be used for any other conversions that are not related to geodetic data. Whichever value is used, it should be used consistently throughout that project.


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Conversion Symbols

The prefixes and symbols listed below are commonly used to form names and symbols of the decimal multiples and sub multiples of the SI units.

Conversion Symbols


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INTERIM UNITS OF MEASURE
As suggested by Federal Standard 376B
January 27, 1993
AS USED IN THE
STANDARD ITEM TABLE		 METRIC EQUIVALENT
ACRE hectare (ha)
CUBIC FOOT cubic meter (m3)
CUBIC YARD cubic meter (m3)
GALLON/MGALLON liter (L), cubic meter (m3)
HUNDRED Hundred for traffic buttons
HUNDRED WEIGHT kilogram (kg)
LINEAR FOOT meter (m)
MBOARD FEET cubic meter (m3)
MILE kilometer (km)
NAUTICAL MILE Nautical Mile
POUND kilogram (kg) for mass
newton (N) for force
SQUARE FOOT square meter (m2)
SQUARE YARD square meter (m2)
TON tonne (t)

 


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UNITS OF MEASUREMENT
USED IN SPECIAL PROVISIONS
AND GENERAL SPECIAL PROVISIONS		 METRIC EQUIVALENT
GAGE; GAUGE METAL THICKNESS gage (mm)
FAHRENHEIT TEMPERATURE kelvin (K) or degree Celsius (C)
FATHOM WATER DEPTH meter (m)
FOOT/LBS TORQUE newton-meter (N-m)
LBS/SQ. IN PRESSURES kilopascal (kPa)
megapascal (MPa)
(if very large number)
LBS/SQ. FT   kilopascal (kPa)
LBS/SQ YD   kilopascal (kPa)
INCH LINEAR millimeter (mm)
KIPS; KSI TENSION kilopascal (kPa) or
megapascal (MPa)
LBS/ACRE EROSION CONTROL kilograms/hectare
LBS/CU. FT. DENSITY kilogram per cubic meter (kg/m3)
MIL THICKNESS micrometer (um)
FT. LBS./SEC. HORSE POWER watt (W)

 


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UNITS OF MEASUREMENTS USED
ON CONTRACT PLANS		 METRIC EQUIVALENT
DEGREES/BEARINGS No change for surveying.
   
STATIONING 1,000 meters = 1 station
   
MILEPOSTS This one is still under review as mileposts are part of the signing issue. Use mileposts for now, but also state kilometerposts.
   
ELEVATIONS meter (m)

 

 

UNITS OF MEASUREMENTS USED IN COMMERCIAL STANDARDS METRIC EQUIVALENT
GALS/HR or MIN (PUMPS) liters per second (L/s)
   
500 GALLON TANKS cubic meter (m3) but it could also possibly be in liter (L)
   
55 GALLON DRUMS cubic meter (m3) or liter (L) for liquid
   
94 LBS/SACK (CEMENT) kilogram (kg)
   
DIAMETER OF REINFORCING STEEL millimeter (mm)
   
LBS/FT OF REINFORCING STEEL kilogram per meter (kg/m)
   
BUSHEL cubic meter (m3)

 

 

 

Length Conversion Factors

Length
To convert from to multiply by
mile (US Statute) kilometer (km) 1.609347
inch (in) millimeter (mm) 25.4 *
inch (in) centimeter (cm) 2.54 *
inch (in) meter (m) 0.0254 *
foot (ft) meter (m) 0.3048 *
yard (yd) meter (m) 0.9144 *

 


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Area Conversion Factors

Area
To convert from to multiply by
square foot (sq ft) square meter (sq m) 0.09290304 E
square inch (sq in) square meter (sq m) 0.00064516 E
square yard (sq yd) square meter (sq m) 0.83612736 E
acre (ac) hectare (ha) 0.4047

 

 

Volume Conversion Factors

Volume
To convert from to multiply by
cubic inch (cu in) cubic meter (cu m) 0.00001639
cubic foot (cu ft) cubic meter (cu m) 0.02831685
cubic yard (cu yd) cubic meter (cu m) 0.7645549
U.S. liquid**
gallon (gal) cubic meter (cu m) 0.00378541
gallon (gal) liter 3.785
fluid ounce (fl oz) milliliters (ml) 29.57353
fluid ounce (fl oz) cubic meter (cu m) 0.00002957

 

 

Force Conversion Factors

Force
To convert from to multiply by
kip (1000 lb) kilogram (kg) 453.6
kip (1000 lb) newton (N) 4,448.222
pound (lb) avoirdupois kilogram (kg) 0.4535924
pound (lb) newton (N) 4.448222


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Pressure or Stress Conversion Factors

Pressure or stress
kip per square inch (ksi) megapascal (MPa) 6.894757
pound per square foot (psf) kilogram per square meter (kg/sq m) 4.8824
pound per square foot (psf) pascal (Pa) 47.88
pound per square inch (psi) pascal (Pa) 6,894.757
pound per square inch (psi) megapascal (MPa) 0.00689476

 

 

Mass Conversion Factors

Mass (weight)
pound (lb) avoirdupois kilogram (kg) 0.4535924
ton, 2000 lb kilogram (kg) 907.1848
grain kilogram (kg) 0.0000648
 
Mass (weight) per length
kip per linear foot (klf) kilogram per meter (kg/m) 0.001488
pound per linear foot (plf) kilogram per meter (kg/m) 1.488
 
Mass per volume (density)
pound per cubic foot (pcf) kilogram per cubic meter (kg/cu m) 16.01846
pound per cubic yard (lb/cu yd) kilogram per cubic meter (kg/cu m) 0.5933


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Temperature Conversion Factors

Temperature
degree Fahrenheit (F) degree Celsius (C) tc=(tF-32)/1.8
degree Fahrenheit (F) kelvin (K) tk = (tF+459.7)/1.8
kelvin (K) degree Celsius (C) tc=tk-273.15
 
Energy and heat
British thermal unit(Btu) joule (J) 1055.056
calorie (cal) joule (J) 4.1868E
Btu/degree F x hr x ft2 W/m2 - degree K 5.678263
kilowatt-hour (kwh) joule (J) 3,600,000E
British thermal unit per pound (Btu/lb) calories per gram (cal/g) 0.55556
British thermal unit per hour (Btu/hr) watt (W) 0.2930711

 

 

Power Conversion Factors

Power
horsepower (hp) (550 ft-lb/sec) watt (W) 745.6999 E
 
Velocity
mile per hour (mph) kilometer per hour(km/hr) 1.60934
mile per hour (mph) meter per second (m/s) 0.44704
 
Permeability
darcy centimeter per second (cm/sec) 0.000968
feet per day (ft/day) centimeter per second (cm/sec) 0.000352
 
*indicates that the factor given is exact.
**One U.S. gallon equals 0.8327 Canadian gallon.
t--A pascal equals 1.000 newton per square meter.
 
Note:
One U.S. gallon of water weighs 8.34 pounds (U.S.) at 60 degrees F.
One cubic foot of water weighs 62.4 pounds (U.S.).
One milliliter of water has a mass of 1 gram and has a volume of one cubic centimeter.
One U.S. bag of cement weighs 94 lbs.


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More Useful Conversion Factors

Quantity From English Units To Metric Units Multiply by*
Length
  mile km 1.609347
yard m 0.9144**
foot m 0.3048**
inch mm 25.40**
 
Area
  square mile km 2 2.590
acre m 2 4047
acre hectare 0.4047
square yard m 2 0.8361
square foot m 2 0.092 90
square inch mm 2 645.2
 
Volume
  acre foot m 3 1 233
cubic yard m 3 0.7646
cubic foot m 3 0.028 32
cubic foot L (1000 cm 3) 28.32
100 board feet m 3 0.2360
gallon L (1000 cm 3) 3.785
 
Mass
  lb kg 0.4536
kip (1000 lb) metric ton (1000kg) 0.4536
 
Mass/unit length
  plf kg/m 1.488
 
Mass/unit area
  psf kg/m 2 4.882
 
Mass density
  pcf kg/m 3 16.02
 
Force
  lb N 4.448
  kip kN 4.448
 
Force/unit length
  plf N/m 14.59
  klf kN/m 14.59
 
Pressure, stress, modules of elasticity
  psf Pa 47.88
  ksf kPa 47.88
  psi kPa 6.895
  ksi MPa 6.895
 
Bending moment, torque, moment of force
  ft-lb N . m 1.356
  ft-kip kN . m 1.356
* 4 significant digits
**denotes exact conversion


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Quantity From English Units To Metric Units Multiply by*
 
Moment of mass
  lb . ft kg . m 0.1383
 
Moment of inertia
  lb . ft2 kg . m 2 0.042 14
 
Second moment of area
  in4 mm4 416 200
 
Section modulus
  in3 mm3 16 390
 
Power
  ton (refrig) kW 3.517
Btu/s kW 1.054
hp (electric) W 745.7
Btu/h W 0.2931
 
Volume rate of flow
  ft 3/s m 3/s 0.028 32
cfm m 3/s 0.000 471 9
cfm L/s 0.4719
mgd m 3/s 0.0438
 
Velocity, speed
  ft/s m/s **0.3048
 
Acceleration
  f/s 2 m/s 2 0.3048
 
Momentum
  lb . ft/sec kg . m/s 0.1383
 
Angular momentum
  lb . ft 2/s kg . m 2/s 0.042 14
 
Plane Angle
  degree rad 0.017 45
  mrad 17.45
* 4 significant digits
**denotes exact conversion


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Pavement Conversion Factors

METRIC CONVERSION – PAVEMENTS
Roadway
Dimensions
Bridge Ht.
PCCP Thickness'
Resilient
Modulus
 
ft
m
ft
m
(inches)
(mm)
psi
MPa
 
Lane
 
12
3.6
14.5
4.4
9
225
3,000
21
 
Shoulder
 
4
1.2
16.0
4.9
10
250
4,000
28
 
10
3.0
    
11
275
5,000
34
         
12
300
10,000
69
             
12,000
83
             
15,000
103
             
20,000
138

 

Typical Density Values
Axle Loads
Tire Loads (per tire width)
 
pcf
kg/m 2
lbs
kN
lbs/inch
kg/mm
PCCP
150
2403
18,000
80
500
9
ACP
137/0.10' depth
2439
  

 

 

TYPICAL QUANTITIES
Asphalt Concrete Paving Quantities (metric tons/kilometer)
Depth of Pavement
(ft)
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
(mm)
30
45
60
75
90
105
120
135
150
165
180
195
210
225

 

 

Width of Pavement
(ft)
(M)
|
Metric tons per kilometer
4
1.2
|
88
132
176
219
263
307
351
395
439
483
527
571
614
658
6
1.8
|
132
198
263
329
395
461
527
593
658
724
790
856
922
988
8
2.4
|
176
263
351
439
527
614
702
790
878
966
1,053
1,141
1,229
1,317
10
3.0
|
219
329
439
549
658
768
878
988
1,097
1,207
1,317
1,427
1,536
1,646
11
3.3
|
241
362
483
604
724
845
966
1,086
1,207
1,328
1,448
1,569
1,690
1,811
12
3.6
|
263
395
527
658
790
922
1,053
1,185
1,317
1,448
1,580
1,712
1,843
1,975
22
6.6
|
483
724
966
1,207
1,448
1,690
1,931
2,173
2,414
2,655
2,897
3,138
3,380
3,621
24
7.2
|
527
790
1,053
1,317
1,580
1,843
2,107
2,370
2,634
2,897
3,160
3,424
3,687
3,950
 
Based on 2439 kg/m 3 ; 30 mm compacted depth = 73.17 kg/m 2

 

 

Pavement Marking Conversion Chart

Wet Material Thickness
Edge Line Coverage
Area Coverage
English mils (0.001")
Metric mm (0.001M)
English Ft/gal
Met./Eng. M/gal
Metric M/Liter
English SF/gal
Met./Eng. SM/gal
Metric SM/Liter
1.0
0.025
4832
1473
393.7
1611
150
39.37
10.0
0.254
483
147
39.4
161
15
3.94
15.0
0.381
322
98.2
26.2
107
10
2.62
19.7
0.500
245
74.8
20.0
82
7.6
2.00
20.0
0.508
242
73.6
19.7
81
7.5
1.97
25.0
0.635
193
58.9
15.7
64
6.0
1.57
30.0
0.762
161
49.1
13.1
54
5.0
1.31
35.0
0.889
138
42.1
11.2
46
4.3
1.12
39.4
1.000
123
37.4
10.0
41
3.8
1.00
40.0
1.016
121
36.8
9.8
40
3.7
0.98
45.0
1.143
107
32.7
8.7
36
3.3
0.87
49.2
1.250
98
29.9
8.0
33
3.0
0.80
50.0
1.270
97
29.5
7.9
32
3.0
0.79
59.1
1.500
82
24.9
6.7
27
2.5
0.67
60.0
1.524
81
24.5
6.6
27
2.5
0.66
78.7
2.000
61
18.7
5.0
20
1.9
0.50
88.6
2.250
55
16.6
4.4
18
1.7
0.44
90.0
2.286
54
16.4
4.4
18
1.7
0.44
98.4
2.500
49
15.0
4.0
16
1.5
0.40
100.0
2.540
48
14.7
3.9
16
1.5
0.39
118.1
3.000
41
12.5
3.3
14
1.3
0.33
120.0
3.048
40
12.3
3.3
13
1.2
0.33
236.2
6.000
20
6.2
1.7
7
0.6
0.17
250.0
6.350
19
5.9
1.6
6
0.6
0.16
255.9
6.500
19
5.8
1.5
6
0.6
0.15
260.0
6.604
19
5.7
1.5
6
0.6
0.15
 
WDB 4.22.97


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Sheet Metal Conversion Factors

SHEET METAL Most specification references use gage number followed by the decimal inch thickness. Example: 22 gage (0.034 inch) Metric specifications use the absolute mm thickness. It is not the intent of this guidance to change the thickness of currently used sheeting. The following chart may be used to specify sheet metal. The thickness under "Specify" is thinner than the actual gage thickness, since specifications give minimum thickness.

Gage
Inch
Exact (mm)
Specify (mm)
Percent Thinner
Than "Exact" Value
32
0.0134
0.3404
0.34
0.1
30
0.0157
0.3988
0.39
2.2
28
0.0187
0.4750
0.47
1.1
26
0.0217
0.5512
0.55
0.2
24
0.0276
0.7010
0.70
0.1
22
0.0336
0.8534
0.85
0.4
20
0.0396
1.0058
1.0
0.6
18
0.0516
1.3106
1.3
0.8
16
0.0635
1.6129
1.6
0.8
14
0.0785
1.9939
1.9
4.7
12
0.1084
2.7534
2.7
1.9
10
0.1382
3.5103
3.5
0.3
8
0.1681
4.2697
4.2
1.6

This schedule was developed since no existing material was found to clearly identify existing sheeting in metric units. Until a more efficient method is developed to address this issue, specifiers may wish to retain the gage number in specifications, and couple this with a rounded mm size in parenthesis.

 

 

Reinforcing Steel Conversion Factors

REINFORCING STEEL

WSDOT Metric projects will continue to use U.S. Customary units on PS&E's.

The following table shows the current U.S. customary rebar sizes in relationship to the respective diameters and cross-sectional areas.

 
Customary English System
Metric Equivalent
U. S. Customary Designation
Diameter (in.)
Area (in 2)
Diameter (mm)
Area (mm 2)
#3
0.375
0.11
9.5
71
#4
0.500
0.20
12.7
127
#5
0.625
0.31
15.9
198
#6
0.750
0.44
19.1
285
#7
0.875
0.60
22.2
388
#8
1.000
0.79
25.4
507
#9
1.125
1.00
28.6
641
#10
1.270
1.27
32.3
817
#11
1.410
1.56
35.8
1007
#14
1.693
2.25
43.0
1452
#18
2.257
4.00
57.3
2581

 

 

Wire Conversion Factors

SEVEN-WIRE, UNCOATED STRAND FOR PRESTRESSED CONCRETE STRUCTURES The prestressing industry again uses the soft conversion for all dimensional units of prestressing wire. This soft conversion is utilized worldwide and a copy of the equivalent physical properties for Grade 270 low-relaxation strand, as provided by Florida Wire and Cable Company, is provided below:

270 GRADE LOW-RELAXATION ASTM A-416
Nominal Strand Diameter
Minimum Strength
Area
(mm)
(in.)
(kN)
(lb.)
(mm 2)
(in 2)
10
(3/8)
102.3
(23,000)
54.8
(0.085)
11
(7/16)
137.9
(31,000)
74.2
(0.115)
12
(15/32)
160.1
(36,000)
85.8
(0.133)
13
(1/2)
183.7
(41,300)
98.7
(0.153)
14
(9/16)
230.0
(51,700)
123.9
(0.192)
15
(0.600)
260.6
(58,600)
140.0
(0.217)


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Sieve Conversion Factors

SIEVES

Sieve Designation (W)
Standard
Alternative
Nominal Sieve Opening
Permissible Variation of Average Opening from the Standard Sieve Designation
Intermediate Tollerance
Maximum Individual Opening
Nominal Wire Diameter
   
(in.)
(y) + or
(x)
(x)
(mm)
 
125 mm
5 in.
5
3.70 mm
130.0 mm
130.9 mm
8.00
106 mm
4.24 in.
4.24
3.20 mm
110.2 mm
111.1 mm
6.40
100 mm
4 in.
4
3.00 mm
104.0 mm
104.8 mm
6.30
90 mm
3 1/2 in.
3.5
2.70 mm
93.6 mm
94.4 mm
6.08
75 mm
3 in.
3
2.20 mm
78.1 mm
78.7 mm
5.80
63 mm
2 1/2 in.
2.5
1.90 mm
65.6 mm
66.2 mm
5.50
53 mm
2.12 in.
2.12
1.60 mm
55.2 mm
55.7 mm
5.15
50 mm
2 in.
2
1.50 mm
52.1 mm
52.6 mm
5.05
45 mm
1 3/4 in.
1.75
1.40 mm
46.9 mm
47.4 mm
4.85
37.5 mm
1 1/2 in.
1.5
1.10 mm
39.1 mm
39.5 mm
4.59
31.5 mm
1 1/4 in.
1.25
1.00 mm
32.9 mm
33.2 mm
4.23
26.5 mm
1.06 in.
1.06
0.80 mm
27.7 mm
28.0 mm
3.90
25.0 mm
1 in.
1
0.80 mm
26.1 mm
26.4 mm
3.80
22.4 mm
 
0.875
0.70 mm
23.4 mm
23.7 mm
3.50
19.0 mm
3/4 in.
0.750
0.60 mm
19.9 mm
20.1 mm
3.30
16.0 mm
 
0.625
0.50 mm
16.7 mm
17.0 mm
3.00
13.2 mm
0.530 in.
0.530
0.41 mm
13.83 mm
14.05 mm
2.75
12.5 mm
1/2 in.
0.500
0.39 mm
13.10 mm
13.31 mm
2.67
11.2 mm
7/16 in.
0.438
0.35 mm
11.75 mm
11.94 mm
2.45
9.50 mm
 
0.375
0.30 mm
9.97 mm
10.16 mm
2.27
8.00 mm
5/16 in.
0.312
0.25 mm
8.41 mm
8.58 mm
2.07
6.70 mm
0.265 in.
0.265
0.21 mm
7.05 mm
7.20 mm
1.87
6.30 mm
1/4 in.
0.250
0.20 mm
6.64 mm
6.78 mm
1.82
5.60 mm
No. 3 1/2
0.223
0.18 mm
5.90 mm
6.04 mm
1.68
4.75 mm
No. 4
0.187
0.15 mm
5.02 mm
5.14 mm
1.54
4.00 mm
No. 5
0.157
0.13 mm
4.23 mm
4 35 mm
1.37
3.35 mm
No. 6
0.132
0.11 mm
3.55 mm
3.66 mm
1.23
2.80 mm
No. 7
0.11
0.095 mm
2.975 mm
3.070 mm
1.10
2.36 mm
No. 8
0.0937
0.080 mm
2.515 mm
2.600 mm
1.00
2.00 mm
No. 10
0.0787
0.070 mm
2.135 mm
2.215 mm
0.900
1.70 mm
No. 12
0.0661
0.060 mm
1.820 mm
1.890 mm
0.810
1.40 mm
No. 14
0.0555
0.050 mm
1.505 mm
1.565 mm
0.725
1.18 mm
No. 16
0.0469
0.045 mm
1.270 mm
1.330 mm
0.650
1.00 mm
No. 18
0.0394
0.040 mm
1.080 mm
1.135 mm
0.580
0.850 mm
No. 20
0.0331
0.035 mm
0.925 mm
0.970 mm
0.510
0.710 mm
No. 25
0.0278
0.030 mm
0.775 mm
0.815 mm
0.450
0.600 mm
No. 30
0.0234
0.025 mm
0.660 mm
0.695 mm
0.390
0.500 mm
No. 35
0.0197
0.020 mm
0.550 mm
0.585 mm
0.340
0.425 mm
No. 40
0.0165
0.019 mm
0.471 mm
0.502 mm
0.290
0.355 mm
No. 45
0.0139
0.016 mm
0.396 mm
0.425 mm
0.247
0.300 mm
No. 50
0.0117
0.014 mm
0.337 mm
0.363 mm
0.215
0.250 mm
No. 60
0.0098
0.012 mm
0.283 mm
0.306 mm
0.180
0.212 mm
No. 70
0.0083
0.010 mm
0.242 mm
0.263 mm
0.152
0.180 mm
No. 80
0.0070
0.009 mm
0.207 mm
0.227 mm
0.131
0.150 mm
No. 100
0.0059
0.008 mm
0.174 mm
0.192 mm
0.110
0.125 mm
No. 120
0.0049
0.007 mm
0.147 mm
0.163 mm
0.091
0.106 mm
No. 140
0.0041
0.006 mm
0.126 mm
0.141 mm
0.076
0.090 mm
No. 170
0.0035
0.005 mm
0.108 mm
0.122 mm
0.064
0.075 mm
No. 200
0.0029
0.005 mm
0.091 mm
0.103 mm
0.053
0.063 mm
No. 230
0.0025
0.004 mm
0.077 mm
0.089 mm
0.044
0.053 mm
No. 270
0.0021
0.004 mm
0.066 mm
0.076 mm
0.037
0.045 mm
No. 325
0.0017
0.003 mm
0.057 mm
0.066 mm
0.030
0.038 mm
No. 400
0.0015
0.003 mm
0.048 mm
0.057 mm
0.025
0.032 mm
No. 450
0.0012
0.003 mm
0.042 mm
0.050 mm
0.028
0.025 mm
No. 500
0.0010
0.003 mm
0.034 mm
0.041 mm
0.025
0.020 mm
No. 635
0.0008
0.003 mm
0.029 mm
0.035 mm
0.020


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Hard Conversions for Construction Materials

HARD CONVERSION FOR CONSTRUCTION MATERIALS
Structural Steel, M270
 
Min. Tensile Strength
Min. Yield Strength
Min. Yield Strength
Grade
(MPa)
(MPa)
(ksi)
 
36
400
250
36
50
450
345
50
50W
485
345
50
70W
620
480
70

 

Reinforcing Bars, M31M
Grade
Tensile and Yield Strengths
Metric
English
Tensile Strength
Min. Yield Strength
Min. Yield Strength
Value
Value
(MPa)
(MPa)
(ksi)
 
300
40
500
300
40
400
60
600
400
60

 

 

Common Concrete Strengths (f'c)
Metric (MPa) 20 28 35 43 48 55
English (psi) 3000 4000 5000 6000 7000 8000

 

 

Coefficient of Thermal Expansion
  Metric Value English Value
Steel 0.0000117/oC 0.0000065/oF
Concrete 0.0000108/oC 0.000006/oF

 

 

Unit Weights
  Metric Value English Value
Steel 7848.3 kg/m3 490 pcf
Concrete 2402.5 kg/m3 150 pcf


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The Construction Trades

THE CONSTRUCTION TRADES

Here are the metric units that will be used by the construction trades. The term "length" includes all linear measurements--length, width, height, thickness, diameter, and circumference.

  Quantity Unit Symbol
 
Surveying
  length kilometer, meter km, m
  area square kilometer km2
    hectare (10,000 m2) ha
    square meter m2
  plane angle degree (non metric) o
    minute (non metric) '
    second (non metric) "
 
Excavating
  length meter, millimeter m, mm
  volume cubic meter m3
 
Trucking
  distance kilometer km
  volume cubic meter m3
  mass metric ton (1000 kg) t
 
Paving
  length meter, millimeter m, mm
  area square meter m2
 
Concrete
  length meter, millimeter m, mm
  area square meter m2
  volume cubic meter m3
  temperature degree Celsius oC
  water capacity liter (1000cm) L
  mass (weight) kilogram, gram kg, g
  cross-sectional area square millimeter mm2


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Pipe Conversion Factors

Pipe is one of the most ubiquitous products in construction. It is made of a wide variety of materials, including galvanized steel, black steel, copper, cast iron, concrete, and various plastics such as ABS, PVC, CPVC, polyethylene, and polybutylene, among others.

But like wood 2-by-4's which are not really 2 inches by 4 inches, pipe is identified by "nominal" or "trade" names that are related only loosely to actual dimensions. For instance, a 2-inch galvanized steel pipe has n inside diameter of about 2-1/8 inches and an outside diameter of about 2-5/8 inches. It is called "2-inch pipe" only for the sake of convenience.

Since few, if any, pipe products have actual dimensions that are in even, round inch-pound numbers, there is no need to convert them to even, round metric numbers. Instead, only their names will change--from inch-pound to metric. Pipe cross sections will not change. Fittings, flanges, couplings, valves, and other piping components will be renamed in like manner as will pipe threads. Here are the inch-pound names for pipe products (called NPS or "nominal pipe size") and their metric equivalents (called DN or "diameter nominal"). The metric names conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, drainage, and miscellaneous piping used in buildings and civil works projects.

NPS
DN
NPS
DN
1/8"
6 mm
8"
200 mm
3/16"
7 mm
10"
250 mm
1/4"
8 mm
12"
300 mm
3/8"
10 mm
14"
350 mm
1/2"
15 mm
16"
400 mm
5/8"
18 mm
18"
450 mm
3/4"
20 mm
20"
500 mm
1"
25 mm
24"
600 mm
1-1/4"
32 mm
28"
700 mm
1-1/2"
40 mm
30"
750 mm
2"
50 mm
32"
800 mm
2-1/2"
65 mm
36"
900 mm
3"
80 mm
40"
1000 mm
3-1/2"
90 mm
44"
1100 mm
4"
100 mm
48"
1200 mm
4-1/2"
115 mm
52"
1300 mm
5"
125 mm
56"
1400 mm
6"
150 mm
60"
1500 mm

**(For pipe over 60 inches, use 1 inch equals 25 mm)

 

 

TABLE 1
PROPOSED METRIC CSP DIAMETER SIZES
Proposed Metric (mm)
Current Standard (inches)
150
6
200
8
250
10
300
12
375
15
450
18
525
21
600
24
675
27
750
30
825
33
900
36
1050
42
1200
48
1350
54
1500
60
1650
66
1800
72
1950
78
2100
84
2250
90
2400
96
2550
102
2700
108
2850
114
3000
120
3150
126
3300
132
3450
138
3600
144

 

 

TABLE 2
Current (inches)
Corrugation Sizes Proposed (millimeters)
2 2/3 x 1/2
68 x 13
3 x 1
76 x 25
5 x 1
125 x 25
3/4 x 3/4 x 7 1/2
19 x 19 x 191
3/4 x 1 x 11 1/2
19 x 25 x 292

 

 

TABLE 3
PIPE WALL THICKNESS
Current
Gage
Nominal Thickness
(inches)
Proposed Nominal Thickness
(millimeters)
16
0.064
1.6
14
0.079
2.0
12
0.109
2.8
10
0.138
3.5
8
0.168
4.3

 

 

TABLE 4
PIPE ARCH SIZES
Corrugations
Corrugations
Inches
Millimeters
Inches
Millimeters
2 2/3 x 1/2
68 x 13
3 x 1 & 5 x 1
76 x 25 & 125 x 25
Span x Rise
Span x Rise
Span x Rise
Span x Rise
       
17 x 13
425 x 325
53 x 41
1325 x 1025
21 x 15
525 x 375
60 x 46
1500 x 1150
24 x 18
600 x 450
66 x 51
1650 x 1275
28 x 20
700 x 500
73 x 55
1825 x 1375
35 x 24
875 x 600
81 x 59
2025 x 1475
42 x 29
1050 x 725
87 x 63
2175 x 1575
49 x 33
1225 x 825
95 x 67
2375 x 1675
57 x 38
1425 x 950
103 x 71
2575 x 1775
64 x 43
1600 x 1075
112 x 75
2800 x 1875
71 x 47
1775 x 1175
117 x 79
2925 x 1975
77 x 52
1925 x 1300
128 x 83
3200 x 2075
83 x 57
2075 x 1425
137 x 87
3425 x 2175
142 x 91
3550 x 2275
    
Note: millimeters equal to inches x 25. Assumed pipe diameters will be x 25.

 

 

TABLE 4A
PIPE ARCH SIZES
Corrugations
Corrugations
(inches)
(millimeters)
3/4 x 3/4 x 7 1/2
19 x 19 x 191
Span x Rise
Span x Rise
   
20 x 16
500 x 400
23 x 19
575 x 475
27 x 21
675 x 525
33 x 26
825 x 650
40 x 31
1000 x 775
46 x 36
1150 x 900
53 x 41
1325 x 1025
60 x 46
1500 x 1150
66 x 51
1650 x 1275
73 x 55
1825 x 1375
81 x 59
2025 x 1475
87 x 63
2175 x 1575
95 x 67
2375 x 1675
Note: millimeters equal to inches x 25. Assumed pipe diameters will be x 25.


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Structural Plate Conversion Factors

STRUCTURAL PLATE DIMENSIONS
 
6 X 2 Corrugation
31 Inch Corner Radius
Span
Rise
R
R
ft-in
ft-in
ft.
ft.
13-3
9-4
6.68
16.05
14-11
10-2
7.48
18.98
16-6
11-0
8.29
21.93
18-1
11-10
9.09
24.98
19-8
12-8
9.90
28.04

 

TABLE 5M
STRUCTURAL PLATE DIMENSIONS
152 x 51 Corrugation
787 mm Corner Radius
(millimeters)
Span
Rise
R
R
4039
2845
2036
4892
4547
3099
2280
5785
5029
3353
2527
6684
5512
3607
2771
7614
5994
3861
3018
8547

 

 

TABLE 6
STRUCTURAL PLATE THICKNESS
Current Specification
Proposed
Gage
Inches
Millimeters
12
.111
2.5
10
.140
3.5
8
.170
4.5
7
.188
-
5
.218
5.5
3
.249
6.5
1
.280
7.0
5/16
.318
8.0
3/8
.377
9.5

 

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