Tube Volume Calculator
Tube is specified by outside diameter and wall thickness, so its bore takes a small extra step. This tube volume calculator lets you enter the OD and wall (or the bore directly) and returns the tubing capacity in litres, millilitres, gallons and cubic inches.
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| متى | ID | الطول | النتيجة |
|---|
Tube is sized by outside diameter and wall. Use OD mode with the wall thickness, or enter the bore.
Tube vs pipe — the sizing difference
The words are often used loosely, but there is a real distinction. Pipe is specified by a nominal size and schedule; tube is specified by its actual outside diameter and a wall thickness (or gauge). So a "1/2-inch tube" really is 0.5 in on the outside, and its bore is 0.5 in minus twice the wall. To get tube capacity, either enter the bore directly or use OD mode and supply the wall thickness so the tool derives the bore.
Capacity from OD and wall
ID = OD − 2 × wall → V = π × (ID/2)² × L
For example, 3 m of 12 mm OD tube with a 1 mm wall has a 10 mm bore, an area of 78.5 mm², and a volume of about 0.236 litres — a little under a cup. Small-bore tubing is where millilitres and cubic inches earn their place in the result panel.
Where tubing capacity matters
- Fluid power and instrumentation — line volume affects response and bleed time.
- Lab and process tubing — internal volume for dead volume and flushing.
- Fuel, oil and brake lines — small but important line contents.
- Aquarium and hobby setups — tubing volume for dosing and turnover.
A note on gauge and drawn tube
Some tube is specified by gauge rather than a decimal wall — the lower the gauge number, the thicker the wall. If you only have a gauge, look up its decimal thickness for your tube standard and enter that as the wall. For drawn or seamless tube with tight tolerances, a direct bore measurement is the most reliable input, and Custom mode accepts it straight away.
Getting tube capacity right
The two things that move the answer are the wall thickness and whether you used OD or ID. Double-check which diameter you have, and remember that for thin-wall tube the bore is close to the OD, while for heavy-wall tube the difference is large. Once the bore is correct, the capacity is exact for a round, uniform tube.
قراءة نتيجتك والثقة بها
A volume figure is only useful if you know what it assumes — so a quick word on reading your tube volume calculator 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.
3/4" OD tubing: contents by length
Tubing is called out by outside diameter and wall, so the bore takes one subtraction first. This tracks a 3/4" OD tube with a 0.049" wall (bore 0.652 in) as the run lengthens.
| الطول (ft) | Volume (US gal) | Per foot |
|---|---|---|
| 10 ft | 0.17 | 0.0173 |
| 25 ft | 0.43 | 0.0173 |
| 50 ft | 0.87 | 0.0173 |
| 100 ft | 1.73 | 0.0173 |
| 250 ft | 4.33 | 0.0173 |
| 500 ft | 8.66 | 0.0173 |
Wall thickness moves the bore
Two tubes with the same outside diameter hold different amounts once the wall changes. Volume in a fixed 100 ft run for common OD/wall pairs, in US gal:
| OD × wall | التجويف (in) | Volume in 100 ft (US gal) |
|---|---|---|
| 1/4" × 0.035" | 0.180 | 0.13 |
| 3/8" × 0.035" | 0.305 | 0.38 |
| 1/2" × 0.049" | 0.402 | 0.66 |
| 3/4" × 0.049" | 0.652 | 1.73 |
| 1" × 0.065" | 0.870 | 3.09 |
Working it through
- Start from a 1/2" OD tube with a 0.049" wall.
- Bore = 0.500 − 2 × 0.049 = 0.402 in, radius 0.201 in.
- Area = π × 0.201² = 0.1269 in²; across 200 ft (2,400 in) = 304.6 in³.
- That equals 1.32 US gal — and it would be larger for a thinner wall at the same OD.
الأسئلة الشائعة
How do I calculate tube volume?
Find the bore (OD minus twice the wall), then apply V = π × (ID/2)² × L. Enter OD and wall in OD mode above, or type the bore directly.
What is the difference between tube and pipe volume?
The calculation is identical; only the sizing differs. Tube is measured by actual OD and wall, while pipe uses nominal size and schedule. Both need the true bore.
How do I find the bore from OD and gauge?
Convert the gauge to a decimal wall thickness for your tube standard, then bore = OD − 2 × wall. Enter OD and that wall in OD mode.
Can I get the result in millilitres?
Yes. The result panel includes millilitres and cubic inches, which suit small-bore tubing.
Related pipe volume tools
What people say
The fill-time estimate turned a vague flush task into a scheduled one. Handy.
Clear about its own limits — tells you when to check manufacturer data. Trustworthy.
Clean and quick on my phone in the field.