Pipe Volume Calculator
Estimate project quantities from your measurements. Confirm technical requirements before making purchases.
Calculate your estimate
Preliminary planning only. Actual requirements depend on site conditions and product specifications.
Use the bore diameter, not the pipe’s outside size
- Find the actual internal diameter in inches from the pipe specification or a reliable measurement. Nominal pipe size is not necessarily the internal diameter.
- Enter the length of one pipe in feet and a whole-number count of identical pipes. Calculate different diameters or lengths separately.
- Keep 7.48052 for US gallons per cubic foot, then select Calculate. The model assumes each pipe is completely full.
Pipe Volume Calculator: formula and assumptions
US gallons = π × (inner diameter in inches ÷ 24)² × pipe length in feet × whole pipe count × gallons per cubic foot.
Worked calculation
A 2 in internal diameter, 100 ft pipe contains 16.32 US gallons using 7.48052 gal/ft³. Two identical pipes contain 32.64 gallons.
What this estimate includes
Use measured internal diameter, not nominal pipe size. Assumes full straight cylindrical pipes; fittings, partial filling, pressure and flow are excluded.
Planning details that change the estimate
The diameter is divided by 24 to convert inches of diameter into feet of radius. Because radius is squared, a diameter mistake has a large effect on capacity: doubling internal diameter multiplies volume by four for the same length. Pipe wall thickness matters only through its effect on the internal bore. This tool estimates storage volume, not pressure loss, flow rate or drain performance; fittings and partially filled pipes are outside the model.
Pipe Volume Calculator FAQs
Can I enter nominal pipe size?
Use actual internal diameter whenever possible. Nominal size and outside diameter can differ from the bore that determines liquid capacity.
Does this work for several pipe sizes?
Calculate each uniform size group separately, then add the gallon results. One averaged diameter does not preserve total volume.
Is the result in US or imperial gallons?
The default factor is for US liquid gallons. Keep units consistent if you deliberately change the conversion factor.
Will this calculate flow or pressure?
No. Capacity is a static geometric volume. Flow and pressure require additional inputs such as roughness, elevation and operating conditions.
Continue planning this project
Estimate a rectangular water body using the Pool Volume Calculator. For the gravel envelope around drainage pipe, use the French Drain Calculator; use the Cubic Yard Calculator for larger rectangular volumes.
RESULTS