Pipe Volume Calculator

Calculate the internal capacity of straight pipe in gallons, liters, cubic feet, and cubic meters. Enter the actual inside diameter or choose a common Schedule 40 PVC reference size.

Measurement system

Inside-diameter reference Nominal size is not inside diameter. Verify critical dimensions with the selected manufacturer.

Actual inside diameterin Enter an inside diameter greater than zero

Pipe length per runft Enter a length greater than zero

Identical pipe runscount Enter a whole number from 1 to 100,000

Fill percentage% 100% gives full internal capacity; lower values estimate a simple volume fraction. Enter a fill percentage from 0% to 100%

Calculation Results

Filled pipe volume

—US gal

Capacity is based on actual inside diameter and straight cylindrical length.

How to calculate pipe volume

Use inside diameter

Measure or obtain the actual inside diameter. Nominal pipe size is a name and can differ from internal diameter by material, schedule, and manufacturer.

Enter straight pipe length

Use the centerline length of each identical straight run. This calculator does not add the internal volume of valves, fittings, vessels, or equipment.

Set quantity and fill

Quantity repeats the same pipe dimensions. A fill below 100% applies a simple fraction of full capacity and is not a partially full hydraulic-flow model.

Verify dimensions before design use

The included Schedule 40 PVC references are conveniences. Confirm critical internal dimensions and system suitability with current product data and project specifications.

Internal pipe-volume formula

A straight pipe bore is modeled as a cylinder. Radius is half of actual inside diameter, and the cross-sectional area is multiplied by length and number of runs.

Inside radius = Inside diameter ÷ 2

Full volume = π × Inside radius² × Length × Quantity

Filled volume = Full volume × Fill percentage ÷ 100

US gallons = Cubic feet × 7.48051948

Liters = Cubic feet × 28.316846592

The calculation estimates contained volume only. It does not calculate flow rate, pressure, thermal expansion, fitting volume, trapped air, drainage geometry, or pipe-system suitability.

Common Schedule 40 PVC inside diameters

Reference dimensions in inches; verify the actual product before critical use.

Nominal size	Inside diameter	Gallons per 100 ft
1/2 in	0.622 in	1.58 gal
3/4 in	0.824 in	2.77 gal
1 in	1.049 in	4.49 gal
1 1/2 in	1.610 in	10.58 gal
2 in	2.067 in	17.43 gal
3 in	3.068 in	38.40 gal
4 in	4.026 in	66.13 gal
6 in	6.065 in	150.08 gal

Methodology, assumptions and sources

The calculator converts dimensions to feet, applies the cylinder formula at full precision, multiplies by quantity and fill fraction, and then converts cubic feet to U.S. gallons, liters, and cubic meters.

Common PVC presets use Schedule 40 inside-diameter references. Charlotte Pipe’s 2026 technical manual identifies product dimension tables and ASTM D1785 Schedule 40 pressure pipe; manufacturer dimensions should be verified whenever they are critical.

Sources:

Charlotte Pipe — Plastics Technical and Installation Manual (updated June 2026) — PVC product dimensions, standards, and verification context.
NIST Handbook 44, Appendix C (2026) — volume and capacity conversions.

Last reviewed: August 2026. This tool is not piping-system design guidance. The cited organizations do not endorse Efficienco.

Frequently asked questions

Should I use nominal pipe size or inside diameter?

Use actual inside diameter. Nominal size can differ from the bore because wall thickness changes by material and schedule.

How many gallons fit in a pipe?

Internal gallons equal cylindrical bore volume converted to U.S. liquid gallons. The result depends on actual inside diameter, length, quantity, and fill percentage.

Does the calculator include elbows, valves, or tanks?

No. It models straight cylindrical pipe only. Add separately determined component and vessel volumes when needed.

Does a partial fill calculate open-channel flow?

No. Fill percentage scales volume only. It does not determine liquid depth, wetted perimeter, slope, velocity, or open-channel capacity.