Plumbing Calculator
Pipe Volume Calculator
Calculate the exact volume of water or fluid held within any length of pipe. Essential for sizing expansion tanks, determining purge times, and planning chemical treatments.
Table of Contents
Calculator Inputs
Results
Total Water Volume
4.49
Gallons
Cubic Feet
0.60
Liters
17.00
Water Weight
37.4 lbs
Pipe Volume Reference Chart
Standard pipe volumes per 100 feet for common piping materials. Note that exact internal diameters vary by pipe schedule and type.
| Nominal Size | Copper Type L (gal/100') | PVC Sch 40 (gal/100') | PEX (gal/100') |
|---|---|---|---|
| 1/2" | 1.21 | 1.57 | 0.92 |
| 3/4" | 2.51 | 2.77 | 1.70 |
| 1" | 4.29 | 4.49 | 2.75 |
| 1-1/4" | 6.53 | 7.77 | 4.10 |
| 1-1/2" | 9.25 | 10.6 | 5.53 |
| 2" | 16.1 | 17.4 | 10.1 |
The Pipe Volume Formula
To manually calculate the volume of a pipe, you first calculate the cross-sectional area of the inside of the pipe, and then multiply by the length.
1. Area (sq inches) = π × (Inner Diameter ÷ 2)²
2. Volume (cubic inches) = Area × Length (in inches)
3. Gallons = Volume ÷ 231
Why 231?
There are exactly 231 cubic inches in one US liquid gallon. If you're working with Imperial gallons (used in the UK), you would divide by 277.42 instead.
Why Calculate Volume?
- Expansion Tanks: Sizing hydronic expansion tanks requires knowing the total system volume.
- Hot Water Wait Time: Calculate how many gallons must be purged before hot water reaches a fixture.
- Chemical Treatments: Knowing the exact volume ensures the correct concentration of glycol or cleaning agents.