# Water Tank Capacity Calculator

Estimate usable water capacity for three tank shapes.

[Open this tool](https://whatson.pk/tank-calculator/)

Category: Construction

A tank's usable water capacity depends on its inside dimensions and the water level, not its external label alone.

Choose the actual tank shape and enter internal measurements. A partly filled horizontal cylinder needs a segment calculation rather than a simple height percentage.

## Inputs and controls

* Tank type: Rectangular; Vertical cylinder; Horizontal cylinder
* Measurement unit: Feet; Metres; Inches; Centimetres; Millimetres
* Length. Allowed range: 0.001 to 100000
* Width. Allowed range: 0.001 to 100000
* Height. Allowed range: 0.001 to 100000
* Cylinder diameter. Allowed range: 0.001 to 100000
* Water height as percentage of tank height (%). Allowed range: 0 to 100

## How to use

* Choose tank type and measurement unit. Enter length, width, height and cylinder diameter.

* Enter water height as percentage of tank height.

* Select Calculate estimate. Read the returned values alongside the assumptions below before copying, exporting or acting on the result.


## Why use this tool

The shape based result helps distinguish total tank capacity from the amount available at a selected fill level.


## Before relying on the result

Use internal dimensions. Horizontal cylindrical tanks use a circular segment for partial water levels.


## Tool limitations

Use internal dimensions. Horizontal cylindrical tanks use a circular segment for partial water levels.

## Questions

### Should I measure outside the tank?

Use internal dimensions for water capacity. Wall thickness and unused space reduce the volume available inside the container.

### What should I check before using Water Tank Capacity Calculator?

Check Tank type, Measurement unit, Length and Width. Use the exact units shown beside the controls and replace any example values with your own inputs.

Source page last modified (UTC): 2026-10-01T14:08:57+00:00

This profile describes the tool. It does not execute it or supply a professional certification.