Pipe Size Calculator (Inches)
Look up NPS pipe dimensions — outer diameter, inner diameter, and wall thickness for Schedule 40, 80, and 160. Includes flow area and flow rate calculator.
Pipe Dimension Lookup
NPS 1" — Schedule 40
ID
1.049"
Outer Diameter
1.315"
Inner Diameter
1.049"
Wall Thickness
0.133"
Flow Area
0.864 in²
OD Circumference
4.131"
Flow Area (ft²)
0.00600 ft²
Flow Rate Calculator
ft/s
GPM
13.5
GPH
808
ft³/s
0.0300
NPS Pipe Reference Table — Schedule 40
Click any row to select that pipe size.
| NPS | OD (in) | SCH40 ID | SCH40 Wall | SCH80 ID | SCH80 Wall |
|---|---|---|---|---|---|
| 1/8" | 0.405 | 0.269 | 0.068 | 0.215 | 0.095 |
| 1/4" | 0.540 | 0.364 | 0.088 | 0.302 | 0.119 |
| 3/8" | 0.675 | 0.493 | 0.091 | 0.423 | 0.126 |
| 1/2" | 0.840 | 0.622 | 0.109 | 0.546 | 0.147 |
| 3/4" | 1.050 | 0.824 | 0.113 | 0.742 | 0.154 |
| 1" | 1.315 | 1.049 | 0.133 | 0.957 | 0.179 |
| 1-1/4" | 1.660 | 1.380 | 0.140 | 1.278 | 0.191 |
| 1-1/2" | 1.900 | 1.610 | 0.145 | 1.500 | 0.200 |
| 2" | 2.375 | 2.067 | 0.154 | 1.939 | 0.218 |
| 2-1/2" | 2.875 | 2.469 | 0.203 | 2.323 | 0.276 |
| 3" | 3.500 | 3.068 | 0.216 | 2.900 | 0.300 |
| 4" | 4.500 | 4.026 | 0.237 | 3.826 | 0.337 |
| 6" | 6.625 | 6.065 | 0.280 | 5.761 | 0.432 |
| 8" | 8.625 | 7.981 | 0.322 | 7.625 | 0.500 |
| 10" | 10.750 | 10.020 | 0.365 | 9.750 | 0.500 |
| 12" | 12.750 | 11.938 | 0.406 | 11.626 | 0.562 |
How to Use
- 1Select the nominal pipe size (NPS)
- 2Choose the pipe schedule (40, 80, or 160)
- 3See OD, ID, wall thickness, and flow area
- 4Enter flow velocity to calculate flow rate
- 5Click any row in the table to switch sizes
Schedule Guide
Schedule 40
Standard — water supply, drain, HVAC, general plumbing
Schedule 80
Heavy-duty — high pressure, industrial, chemical
Schedule 160
Extra-heavy — extreme pressure, oil/gas, very thick walls