Calculator Inputs
This page uses a single stacked layout. The input grid becomes three columns on large screens, two on smaller screens, and one on mobile.
Example Data Table
| Scenario | Shape | Sample Dimensions | Freeboard | Reserve | Approx. Gross Capacity | Typical Use |
|---|---|---|---|---|---|---|
| Plant utility tank | Rectangular | 4.0 m × 2.5 m × 2.2 m | 5% | 10% | 22,000 L | Process water storage |
| Rooftop service tank | Vertical cylinder | Diameter 2.2 m, height 2.8 m | 6% | 8% | 10,645 L | Building domestic supply |
| Farm supply tank | Horizontal cylinder | Length 5.5 m, diameter 1.8 m | 8% | 12% | 13,996 L | Irrigation reserve |
| Pressure vessel | Sphere | Diameter 2.4 m | 4% | 10% | 7,238 L | Compact high-volume storage |
Formula Used
Primary volume formulas
Rectangular tank: Volume = Length × Width × Height
Vertical cylinder: Volume = π × r² × Height
Horizontal cylinder: Filled volume = Circular segment area × Length
Sphere: Volume = 4/3 × π × r³
Partially filled sphere: Volume = π × h² × (3r − h) ÷ 3
Working and operating metrics
Working depth: Total height × (1 − Freeboard %)
Usable volume: Working volume × (1 − Reserve %)
Bottom pressure: Density × g × Liquid depth
Water mass: Filled volume × Density
Fill time: Usable liters ÷ Inlet flow rate
All calculations use SI conversions internally. Enter values in one chosen dimension unit, and the calculator converts them before solving.
How to Use This Calculator
- Select the tank shape that matches your storage geometry.
- Choose one dimension unit for all dimensional inputs.
- Enter the physical size values needed for that shape.
- Type the current liquid level to estimate stored water and pressure.
- Set freeboard and reserve percentages to model safe operating capacity.
- Add inlet and outlet flow rates for fill and drain time estimates.
- Enter daily demand to see how many days usable storage can support.
- Press Calculate Capacity to show results above the form.
- Use the CSV and PDF buttons to export the calculated output.
FAQs
1. What does gross capacity mean?
Gross capacity is the full geometric volume of the tank when filled to its physical maximum. It does not account for freeboard, safety space, or reserve storage.
2. Why is usable capacity lower than gross capacity?
Usable capacity is reduced by freeboard and reserve settings. That adjustment reflects safer operation, overflow prevention, and emergency storage planning.
3. Can I use this for tanks that are partially filled?
Yes. Enter the current liquid level and the calculator estimates stored water, fill percentage, water mass, and bottom pressure for that partial condition.
4. Which density should I use for clean water?
For fresh water near room temperature, 997 kg/m³ is a practical default. If temperature or salinity changes significantly, use a more accurate density value.
5. How is fill time estimated?
Fill time is calculated by dividing usable storage in liters by the inlet flow rate in liters per minute. Losses and pump cycling are not included.
6. Does the calculator check structural design?
No. It estimates storage and hydrostatic metrics only. Structural adequacy, wall thickness, supports, uplift, code compliance, and seismic design require engineering review.
7. What shapes are supported here?
This version supports rectangular tanks, vertical cylinders, horizontal cylinders, and spheres. Those shapes cover many common engineering, utility, industrial, and agricultural uses.
8. Are the exported CSV and PDF files customizable?
Yes. The CSV exports the main computed metrics, while the PDF captures the visible result section including summary cards, details, and the plotted chart.