Pipe Volume Calculator
Use this pipe volume calculator to find how much a pipe holds from its inner diameter and length, using volume = π × (d ÷ 2)² × L. Enter the inner diameter, or the outer diameter and wall thickness, then read cubic inches, feet, yards and meters, liters, gallons and the weight of the water.
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Use the inside diameter, which is the open bore the water fills, not the outside diameter.
US gallons
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Liters
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Cubic feet (cu ft)
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Imperial gallons
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Cubic inches (cu in)
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Cubic yards (cu yd)
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Cubic meters (m³)
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Cubic centimeters (cm³)
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Weight of water
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Inner diameter used
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US gallons per foot
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Volume = π × (inner diameter ÷ 2)² × length × quantity × fill. 1 cu ft = 7.48052 US gal; 1 US gal = 3.785 L; 1 imperial gal = 4.546 L. Water weight uses 1 kg per liter (about 8.345 lb per US gallon) and does not include the pipe itself. A nominal pipe size is not the real inside diameter, so measure the ID or use the OD and wall thickness.
Common Schedule 40 steel pipe sizes
| Nominal size | OD (in) | ID (in) | US gal per ft |
|---|---|---|---|
| 1/2″ | 0.840 | 0.622 | 0.016 |
| 3/4″ | 1.050 | 0.824 | 0.028 |
| 1″ | 1.315 | 1.049 | 0.045 |
| 1-1/4″ | 1.660 | 1.380 | 0.078 |
| 1-1/2″ | 1.900 | 1.610 | 0.106 |
| 2″ | 2.375 | 2.067 | 0.174 |
| 3″ | 3.500 | 3.068 | 0.384 |
| 4″ | 4.500 | 4.026 | 0.661 |
| 6″ | 6.625 | 6.065 | 1.501 |
OD and ID from ASME B36.10M for Schedule 40 steel pipe; gallons per foot are calculated from the ID. Other materials and schedules have different walls, so check your own pipe.
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How it works
- How do you calculate the volume of a pipe?
- Treat the pipe as a cylinder: volume = π × (inner diameter ÷ 2)² × length, with both in the same unit. A pipe with a 2 in inner diameter and 10 ft (120 in) length holds π × 1² × 120 = 376.99 cu in, which is 1.632 US gallons.
- Should I use the inner or outer diameter?
- Use the inner diameter, the open bore that holds the fluid. If you only know the outer diameter, subtract twice the wall thickness: ID = OD − 2 × wall. For NPS 2 Schedule 40 steel pipe, 2.375 − 2 × 0.154 = 2.067 in.
- How many gallons are in a foot of pipe?
- It depends on the inner diameter: gallons per foot = π × (ID ÷ 2)² × 12 ÷ 231 with ID in inches. A 1 in ID holds about 0.0408 gal per foot, 2 in about 0.1632 gal and 4 in about 0.6528 gal.
- How much water is in 100 feet of pipe?
- For a 4 in inner diameter, 100 ft holds 0.6528 × 100 = 65.28 US gallons, or about 247 liters. Water weighs roughly 8.345 lb per US gallon, so that is about 545 lb of water, not counting the pipe.
- How do I convert cubic feet to gallons?
- Multiply cubic feet by 7.48052 to get US gallons, because 1 cu ft = 1,728 cu in and 1 US gallon = 231 cu in. For example, 2 cu ft × 7.48052 = 14.96 US gallons. Divide by 7.48052 to go back.