Pipe Volume Calculator

Calculate the volume of water inside a pipe using inside diameter and pipe length. Estimate pipe capacity in gallons, liters, cubic feet, cubic inches, cubic meters, pipe area, pipe weight of water, fill time, and drain time.

Calculate Pipe Volume

Pipe Volume = π × Radius² × Length.
Your result will appear here.

How the pipe volume calculator works

Diameter and length:
The calculator converts inside diameter and pipe length into feet, calculates circular pipe area, then multiplies by length to estimate volume.

Radius and length:
Enter the inside radius directly if you already know it. The calculator uses π × radius squared × length.

Known area and length:
Enter the known inside area of the pipe and pipe length to calculate volume.

Nominal pipe size:
Select a common nominal size to estimate volume using a typical inside diameter.

Why use a pipe volume calculator?

A pipe volume calculator helps estimate how much water is held inside a pipe run before filling, draining, flushing, winterizing, or sizing a system.

It can help compare gallons, liters, cubic feet, cubic inches, cubic meters, fill time, drain time, water weight, pipe area, and volume per foot.

What your result means

Your result shows estimated pipe volume based on the inside pipe diameter or area, pipe length, number of pipes, and fill percentage. These values are estimates only. Actual pipe volume can vary based on pipe material, wall thickness, fittings, slope, trapped air, and whether the pipe is completely full.

Pipe volume formulas

Frequently asked questions

How do you calculate pipe volume?

Calculate the inside area of the pipe, then multiply that area by the pipe length. For a round pipe, the formula is π × radius squared × length.

Should I use inside diameter or outside diameter?

Use inside diameter. Pipe volume is based on the open space inside the pipe where water or fluid can flow.

How do you calculate gallons in a pipe?

Calculate the pipe volume in cubic feet, then multiply cubic feet by 7.48052 to convert to gallons.

Is this pipe volume calculator exact?

No. This calculator gives a close estimate. Real pipe volume can vary based on actual inside diameter, pipe material, wall thickness, fittings, slope, and fill level.