Calculator Inputs
Choose a tank shape, enter dimensions, add engineering allowances, and submit to estimate total, filled, usable, and reserved capacity.
Example Data Table
| Case | Shape | Main Dimensions | Fill Depth | Full Capacity | Usable Working Capacity |
|---|---|---|---|---|---|
| Example 1 | Rectangular | 1.80 m × 1.20 m × 0.90 m | 0.65 m | 1,944.00 L | 1,749.60 L |
| Example 2 | Horizontal Cylinder | Length 2.40 m, Diameter 1.20 m | 0.70 m | 2,714.34 L | 2,388.62 L |
| Example 3 | Vertical Cylinder | Height 2.00 m, Diameter 1.10 m | 1.20 m | 1,900.66 L | 1,672.58 L |
Formula Used
1) Rectangular tank
Full volume: V = L × W × H
Filled volume: Vfilled = L × W × h
2) Vertical cylindrical tank
Full volume: V = πr²H
Filled volume: Vfilled = πr²h
3) Horizontal cylindrical tank
Full volume: V = πr²L
Filled volume: Vfilled = Asegment × L, where Asegment = r²cos-1((r-h)/r) − (r-h)√(2rh − h²)
4) Spherical tank
Full volume: V = 4πr³ / 3
Filled volume: calculated from the spherical segment defined by liquid depth h
5) Operating adjustments
Recommended maximum fill: Full volume × (Safety fill − Expansion allowance)
Usable working capacity: Recommended maximum fill − Dead volume
Fuel mass: Filled volume × density
How to Use This Calculator
- Select the tank shape that matches your design.
- Choose the dimension unit for all size inputs.
- Enter tank dimensions such as length, width, height, or diameter.
- Enter the current liquid depth measured from the bottom.
- Add the fuel density to estimate current mass and weight.
- Enter dead volume, safety fill, and expansion allowance percentages.
- Press Calculate Capacity to see results above the form.
- Review the Plotly curve to understand how depth changes stored volume.
- Use the CSV and PDF buttons to save engineering results.
FAQs
1) What does dead volume mean in a fuel tank?
Dead volume is the portion that cannot be withdrawn during normal operation. It may remain below outlets, around baffles, or inside sump zones. This calculator subtracts it from recommended operating volume.
2) Why is safety fill limit important?
A safety fill limit prevents overfilling, sloshing loss, vent blockage, and expansion problems. It is often lower than geometric capacity because real tanks need practical operating headspace.
3) Why is expansion allowance separate from safety fill?
Expansion allowance reserves additional empty space for temperature growth of the fuel. Keeping it separate helps engineers compare normal operating margin with thermal protection margin.
4) When should I use current liquid depth?
Use current liquid depth when you know the measured level but not the stored quantity. The calculator converts that depth into filled volume based on the selected tank geometry.
5) Why is the horizontal cylinder curve not linear?
In a horizontal cylinder, the liquid cross-section changes shape as depth rises. Because the wetted segment area grows nonlinearly, volume does not increase at a constant rate.
6) Can I use this for diesel, gasoline, or aviation fuel?
Yes. Enter the appropriate density for the fluid being stored. The geometry stays the same, while mass and weight outputs change with density.
7) Does this calculator replace detailed tank calibration?
No. It is excellent for design checks, quick estimates, and preliminary sizing. Certified custody transfer or regulated storage still needs formal calibration and site-specific validation.
8) What unit system does the result support?
Dimensions can be entered in metric or imperial units. Results are reported in cubic meters, liters, and US gallons, making cross-checking easier during design review.