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Inch sizes relate to the nominal (approx.) bore of the PIPE and are not literal physical dimensions.

• For instance, 1" Pipe DOES NOT measure 25mm in diameter.
• Therefore a   1" Socket DOES NOT measure 25mm internally.

The below tables provide a dimensional reference for Imperial and Metric pipes, and their acceptable tolerances. A tolerance is the allowable limit of variation (represented as min and max) of a specific pipe size. For example; a 1" pipe should measure 33.6mm however may measure as low as 33.4mm and as high as 33.7mm.

 
Nominal Size Actual Size Acceptable Tolerances
inches millimeters min max
3/8" 17.1 17.0 17.3
1/2" 21.4 21.2 21.5
3/4" 26.7 26.6 26.9
1" 33.6 33.4 33.7
1 1/4" 42.2 42.1 42.4
1 1/2" 48.3 48.1 48.4
2" 60.3 60.2 60.5
2 1/2" 75.2 75.0 75.3
3" 88.9 88.7 89.1
4" 114.3 114.1 114.5
5" 140.2 140.0 140.5
6" 168.3 168.0 168.5
8" 219.1 218.8 219.4
10" 273.0 272.6 273.4
12" 323.9 323.4 324.3
14" 355.6 355.0 356.1
16" 406.4 405.9 406.9
18" 457.2 456.7 457.7

Nominal (Inch) pipe sizes and their respective tolerances

 
Metric Size Acceptable Tolerances
millimeters min max
12 12.0 12.2
16 16.0 16.2
20 20.0 20.2
25 25.0 25.2
32 32.0 30.2
40 40.0 40.2
50 50.0 50.2
63 63.0 63.3
75 75.0 75.3
90 90.0 90.3
110 110.0 110.4
125 125.0 125.4
140 140.0 140.5
160 160.0 160.5
180 180.0 180.6
200 200.0 200.6
225 225.0 225.7
250 250.0 250.8
280 280.0 280.9
315 31.5.0 316.0
355 355.0 356.1
400 400.0 401.2
450 450.0 451.4
500 500.0 501.5

Metric pipe sizes and their respective tolerances

 

Factors affecting Diameter

• Wall thickness

• Pressure Class

• Grade Type of ISO

• Manufacturing Standards


Please always refer to the relevant Data Sheets for the specific pipe, fitting, valve or flange before purchasing.