# Pipe Volume Calculator

URL: https://speedycalculator.com/calculators/construction/pipe-volume/
Last updated: 2026-10-25

> The pipe volume calculator finds the volume of liquid a pipe holds from its inner diameter and length, in gallons, litres and cubic feet, and the weight of water, oil, fuel or glycol in it.

## Inputs

- Inner diameter (in, mm, cm, m)
- Pipe length (ft, m, in, yd, cm)
- Number of pipes
- Liquid

## Results

- Volume
- Weight of liquid
- Volume per length

## Formula

```
Volume = π × (ID ÷ 2)² × length × number of pipes
Mass = volume × liquid density
```

## Explanation

Knowing the volume of a pipe run helps when filling a heating system with antifreeze, flushing or disinfecting a water main, calculating dead legs or estimating the weight of a full line on its supports. Use the inside diameter, not the nominal size.

### How to use the Pipe Volume Calculator

- **Inner diameter**
- **Pipe length**
- **Number of pipes**
- **Liquid**
- Every result field is editable: type into **Volume** and **Pipe length** plus every other field update to match.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the inner diameter, the length of the run and the number of identical pipes, and pick the liquid.

### Tips for an accurate estimate

- Measure inside dimensions of tanks and pools – wall thickness can change the volume noticeably.
- Use the average depth for pools with a sloping floor.
- Remember the weight: water weighs about 8.34 lb per US gallon (1 kg per litre), so large volumes need solid support.
- Check whether a figure is in US gallons, imperial gallons or litres before ordering chemicals or equipment.

### Common mistakes to avoid

- Using wall height instead of water depth for above-ground pools.
- Assuming a horizontal tank's volume is proportional to the liquid level – it is not.
- Mixing up flow units such as GPM, GPH and litres per minute.

### Inputs explained

FieldWhat to enterInner diameterUnits: in, mm, cm, mPipe lengthUnits: ft, m, in, yd, cmNumber of pipesA numberLiquidChoose one: Water, Seawater, Glycol 50%, Diesel …

### What each result means

- **Volume** = pi×([Inner diameter]÷2)^2×[Pipe length]×[Number of pipes]
- **Weight of liquid** = [Volume]×[Liquid]
- **Volume per length** = pi×([Inner diameter]÷2)^2

### Example values

How the main result changes when **Pipe length** changes and everything else stays at the example values above:

Pipe length (ft)Volume (US gal)502.04753.061004.081255.11506.122008.16

## Worked example

Inputs — Inner diameter: 1 in; Pipe length: 100 ft; Number of pipes: 1; Liquid: Water.

Results — **Volume = 4.08 US gal**; Weight of liquid = 34.05 lb; Volume per length = 0.0408 gal/ft.

## FAQ

**How much water is in 100 ft of 1 in pipe?**
About 4.1 gallons (15.4 L).

**How do I calculate pipe volume?**
π × (inner radius)² × length; for gallons with dimensions in inches and feet: 0.0408 × ID² × length.

**Why use the inside diameter?**
Nominal pipe sizes do not equal the bore; Schedule 40, 80 and copper types all have different inside diameters.

**What formula does the Pipe Volume Calculator use?**
Volume = π × (ID ÷ 2)² × length × number of pipes.