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Water Tank Volume Calculator — Liters, Gallons & Fill Level

Calculate rectangular or vertical cylindrical tank capacity and filled volume from inside dimensions, with liters, cubic meters and US gallons.

Result

3,000 L

3 m³ · 792.52 US gal

Filled at entered depth: 3,000 L

Formula and worked example

Rectangular: V=L×W×H. Vertical cylinder: V=π×(D/2)²×H. Filled volume uses entered fill depth.

A 2 m × 1.5 m × 1 m rectangular tank holds 3 m³ = 3,000 L before freeboard.

Assumptions

  • Use inside dimensions, not outside dimensions.
  • Flat-ended rectangular or vertical cylindrical geometry only.

Last updated: 2026-09-16

Frequently asked questions

How many liters are in one cubic meter?

Exactly 1,000 liters.

Should I use inside dimensions?

Yes. Wall thickness reduces usable internal capacity.

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