Pipe Volume Calculator
This pipe volume calculator estimates the volume of a pipe as well as the mass of a liquid that flows through it. It is a helpful tool for everyone who needs to know the exact volume of water (or any other liquid) in a pipe — whether you are designing an irrigation system for your garden, calculating the capacity of a heating system, or checking if the pipe diameter you have chosen will be sufficient for refilling a garden pond.
All you need to do is enter the pipe's inner diameter and length. You can freely switch between metric (mm, cm, m) and imperial (in, ft) units using the toggle at the top of the form. The liquid density defaults to water (997 kg/m³), but you can change it for any other fluid.
Volume of a Pipe – Formula
By shape, a pipe is a hollow right cylinder. The volume of a cylinder is given by:
V = π × r² × L
where:
- V — volume of the pipe (the space inside it)
- r — inner radius of the pipe (= inner diameter / 2)
- L — length (height) of the pipe
- π ≈ 3.14159265
Important: always use the inner diameter, not the outer diameter, to get the volume of liquid the pipe can hold.
Volume of Water in Pipe – Calculation Example
Let's say you have a pipe with an inner diameter of 10 cm and a length of 5 m.
- Convert diameter to meters: 10 cm = 0.10 m → radius = 0.05 m
- Calculate volume: V = π × (0.05)² × 5 = 3.14159 × 0.0025 × 5 ≈ 0.03927 m³
- Convert to liters: 0.03927 m³ × 1000 = 39.27 L
- Mass of water: 39.27 L × 0.997 kg/L ≈ 39.15 kg
Unit Conversions
The calculator automatically converts the pipe volume to all common units:
- Metric: mm³, cm³, L (liters), m³
- Imperial: in³, ft³, US gallons, UK gallons
Liquid Density Presets
| Liquid | Density (kg/m³) | Density (lb/ft³) |
|---|---|---|
| Water (20°C) | 997 | 62.24 |
| Seawater | 1025 | 63.99 |
| Milk | 1030 | 64.30 |
| Diesel fuel | 850 | 53.06 |
| Gasoline | 750 | 46.82 |
| Vegetable oil | 800–900 | 49.9–56.2 |
| Mercury | 13,534 | 845 |
FAQs
What is the difference between inner diameter and outer diameter?
The inner diameter (also called bore or internal diameter) is the diameter of the space inside the pipe through which the liquid flows. The outer diameter includes the pipe wall thickness. For volume calculations, always use the inner diameter.
How do I convert pipe volume to gallons?
Multiply the volume in cubic feet (ft³) by 7.48052 to get US gallons, or multiply liters by 0.264172.
Why does the liquid density matter?
The volume of the pipe does not depend on what fills it — but the mass (weight) of the liquid does. Water at room temperature weighs about 997 kg per cubic meter (8.34 lb/gal). If you are filling the pipe with a heavier fluid like mercury or a lighter fluid like gasoline, you need to enter the correct density to get an accurate weight.
Can I use this calculator for irrigation pipes?
Yes! Enter the inner diameter and total length of your irrigation pipe to find out how much water it holds. This is useful for calculating water consumption, planning pump capacity, and sizing pressure tanks.
What units can I use?
The calculator supports both metric (mm, cm, m) and imperial (in, ft, yd) units for diameter and length. Density can be entered in kg/m³, g/cm³, lb/ft³, or lb/gal. Results are displayed in all common volume and weight units simultaneously.