Pipe Volume Calculator — Gallons
Need the answer in gallons? Enter the bore and length and this pipe volume calculator in gallons gives you US gallons and Imperial gallons side by side, plus the handy gallons-per-foot figure most plumbers keep in their heads.
نفس الحجم بكل وحدة
وزن السائل
وقت الملء / التفريغ المقدر
حساباتك الأخيرة (محفوظة على هذا الجهاز)
| متى | ID | الطول | النتيجة |
|---|
Default output is US gallons. Switch the Imperial tab for UK gallons, or the result unit menu for litres.
US gallons vs Imperial gallons
Gallons are not one unit. A US gallon is 3.785 litres; an Imperial (UK) gallon is 4.546 litres — about 20% larger. Getting them mixed up on a fuel or water calculation is a real error, so the result panel labels both clearly. Pick US on the units tab for North American work and Imperial for the UK.
Gallons per foot of pipe
A lot of field estimating is really "gallons per foot × length". Because the bore is squared in the formula, capacity climbs fast with size: doubling the diameter roughly quadruples the volume. The table below covers Schedule 40; the calculator handles any bore, any fill level and part-full lines.
| الحجم الاسمي | Inside diameter | US gal / ft | US gal / 100 ft |
|---|---|---|---|
| 1/2" | 0.622" | 0.016 | 1.58 |
| 3/4" | 0.824" | 0.028 | 2.77 |
| 1" | 1.049" | 0.045 | 4.49 |
| 1-1/4" | 1.380" | 0.078 | 7.77 |
| 1-1/2" | 1.610" | 0.106 | 10.58 |
| 2" | 2.067" | 0.174 | 17.43 |
| 2-1/2" | 2.469" | 0.249 | 24.87 |
| 3" | 3.068" | 0.384 | 38.40 |
| 4" | 4.026" | 0.661 | 66.13 |
| 5" | 5.047" | 1.039 | 103.93 |
| 6" | 6.065" | 1.501 | 150.08 |
| 8" | 7.981" | 2.599 | 259.88 |
| 10" | 10.020" | 4.096 | 409.63 |
| 12" | 11.938" | 5.815 | 581.46 |
| 24" | 22.624" | 20.883 | 2088.32 |
Working out pipe volume in gallons by hand
If you want to check the tool, the manual route in US units is:
- Find the cross-sectional area in square inches:
π × (ID/2)². - Multiply by the length in inches to get cubic inches.
- Divide by 231 (cubic inches per US gallon).
Example: 100 ft of 2-inch Schedule 40 (bore 2.067 in). Area = 3.356 in²; length = 1,200 in; volume = 4,027 in³ ÷ 231 ≈ 17.4 US gallons. For Imperial, divide the cubic inches by 277.4 instead.
Why people want gallons specifically
- Shock chlorination and dosing — chemical rates are quoted per gallon of system water.
- Pool and irrigation top-ups — knowing line contents avoids over- or under-filling.
- Water heater and boiler loops — system gallons drive expansion-tank sizing.
- Fuel and oil transfer lines — line contents in gallons matter for inventory and spills.
After the gallons figure
Once you have gallons, the weight often comes next: water is about 8.34 lb per US gallon, so a 50-gallon system holds roughly 417 lb of water. The calculator shows that weight automatically, and if you enter a flow rate in gallons per minute it estimates how long the line takes to fill or drain.
قراءة نتيجتك والثقة بها
A volume figure is only useful if you know what it assumes — so a quick word on reading your pipe volume calculator gallons result.
How to interpret the result
The headline value is the internal capacity of a round, uniform pipe running full — the fluid the bore can hold along the length you entered. Every other unit on the panel is the same physical quantity re-expressed, so you can quote whichever your paperwork needs without recalculating.
افتراض الأنبوب الممتلئ
By default the figure assumes the pipe is completely full and perfectly cylindrical. For gravity drains and vented lines that run part full, set a fill level below 100% and the result scales with it. Bends, valves and fittings add a little capacity the straight-length model does not see — use the fittings allowance to approximate them.
جداول مرجعية للسعة ومثال محلول
Concrete numbers for this page, calculated the same way the tool above does — use them as a quick check or a lookup.
Schedule 40 2" pipe: volume by run length
How much a 2" Schedule 40 bore holds as the run gets longer, in US gal. The per-foot figure is constant, so any length is one multiplication away.
| الطول (ft) | Volume (US gal) | Per foot |
|---|---|---|
| 10 ft | 1.74 | 0.1743 |
| 25 ft | 4.36 | 0.1743 |
| 50 ft | 8.72 | 0.1743 |
| 100 ft | 17.43 | 0.1743 |
| 250 ft | 43.58 | 0.1743 |
| 500 ft | 87.16 | 0.1743 |
Schedule 40 pipe: volume across sizes
Volume held by a fixed 100 ft run across common Schedule 40 sizes, in US gal. Doubling the diameter roughly quadruples the capacity.
| الحجم الاسمي | التجويف (in) | Volume in 100 ft (US gal) |
|---|---|---|
| 1/2" | 0.622 | 1.58 |
| 3/4" | 0.824 | 2.77 |
| 1" | 1.049 | 4.49 |
| 1-1/2" | 1.610 | 10.58 |
| 2" | 2.067 | 17.43 |
| 3" | 3.068 | 38.40 |
| 4" | 4.026 | 66.13 |
| 6" | 6.065 | 150.1 |
مثال محلول، خطوة بخطوة
- Bore = 2.067 in, so radius = 1.0335 in.
- Area = π × radius² = 3.3556 in².
- Length = 75 ft = 900 in; volume = 3.3556 × 900 = 3,020.0 in³.
- Convert to the unit you need: 13.07 US gal for a 75 ft run of Schedule 40 2" pipe.
الأسئلة الشائعة
How many gallons are in a pipe?
Multiply the gallons-per-foot for your pipe size by the length in feet. A foot of 1-inch Schedule 40 holds about 0.045 US gallons; a foot of 4-inch holds about 0.66. Enter your exact size and length above for a precise figure in US or Imperial gallons.
How do I convert pipe volume to US gallons?
Find the volume in cubic inches, then divide by 231. For litres to US gallons, divide litres by 3.785. The calculator does both for you.
What is the difference between US and Imperial gallons for pipe volume?
An Imperial gallon is about 20% larger (4.546 L vs 3.785 L), so the same pipe holds fewer Imperial gallons than US gallons. Always state which gallon you mean on shared paperwork.
Does the gallons result assume the pipe is full?
By default yes, 100% full. Open Advanced and set a fill level below 100% for part-full lines such as gravity drains, and the gallons figure scales accordingly.
Related pipe volume tools
What people say
Used the litres-per-metre figures to size a glycol charge for a radiant job. Numbers matched the datasheet.
Switches between US and metric without losing the pipe. Small thing, big time-saver.
Would love more HDPE DIPS sizes, otherwise excellent.