Horizontal Tank Volume Calculator
By Santaji GadepatilinUpdated October 27, 2026
Liquid volume (L) vs Liquid level (m) — other inputs held at your current values.
How to use this calculator
Enter the tank’s inner diameter, straight length and the liquid level measured from the bottom. You get the liquid volume, the total tank volume and the percentage filled. To create a strapping table for a level transmitter, change the level in steps and note each volume — or watch the chart.
The formula
For a horizontal cylinder of radius r = D/2 and level h:
V = L × [ r² cos⁻¹((r − h) ÷ r) − (r − h) √(2rh − h²) ]
Worked example
A tank 2 m in diameter and 5 m long with 0.5 m of liquid:
- r = 1 m, r − h = 0.5 m
- Segment area = 1 × cos⁻¹(0.5) − 0.5 × √0.75 = 1.0472 − 0.4330 = 0.6142 m²
- V = 0.6142 × 5 = 3,071 litres — only 19.6% full at 25% of the height
Level vs volume (any horizontal cylinder)
| Level (% of D) | Volume (% full) |
|---|---|
| 12.5% | 7.2% |
| 25% | 19.6% |
| 50% | 50% |
| 75% | 80.4% |
| 87.5% | 92.8% |
Using it with a level transmitter
A pressure or radar transmitter measures level. To display volume, the control system needs this non-linear curve (a strapping table). Combine with the hydrostatic pressure calculator to go from pressure to level first.
Frequently asked questions
Why isn't volume proportional to level in a horizontal tank?
The tank is widest in the middle, so each centimetre of level holds more liquid near the centre than near the top or bottom. At 25% of the diameter the tank is only about 20% full.
Does this include dished or hemispherical ends?
No. It calculates the cylindrical shell only. Heads add extra volume; the calculator gives the shell part, which is most of the tank for long vessels.
Can I find the level for a given volume?
Yes. Press × on Liquid level, then type the volume. The level is solved numerically.