Calculate water volume in gallons or liters for a rectangular tank or pool, round tank, well or horizontal tank from inside dimensions, or find fill depth.

Use inside dimensions. Blank optional water depth means full capacity.

Partial fill and result unit
Blank means full. Enter 0 for empty; depth cannot exceed height or diameter.

Water Volume Formula

For a rectangular container, water volume is length × width × water depth. A vertical cylinder uses π × radius² × depth. A horizontal cylinder uses tank length × circular-segment area, as described in Wolfram MathWorld. The interface converts measurements to meters and cubic meters before calculating. The rectangular rearrangements below are general algebraic references; length and width are not interface solve modes.

V = L × W × D
L = V / (W × D)
W = V / (L × D)
D = V / (L × W)
  • V = water volume
  • L = water length
  • W = water width
  • D = water depth

Choose volume or fill depth, then the container shape. Volume mode requires inside dimensions; optional water depth defaults to full capacity when blank, while an entered zero means empty. Depth mode requires dimensions and a known volume from zero through capacity. Overfull depth or volume is rejected.

Each input unit selector converts its current quantity. Results include US gallons, Imperial gallons, liters, cubic feet and cubic meters. The primary result unit is in the optional disclosure. Ideal geometry excludes rounded ends, sloped walls, freeboard, fittings and displaced objects; estimated mass assumes1 kg/L.

Water Volume Unit Conversions

These are the main conversion values used when switching between measurement units.

Measurement Equivalent
1 cubic foot 7.48052 US gallons
1 cubic foot 28.3168 liters
1 cubic meter 35.3147 cubic feet
1 meter 3.28084 feet
1 inch 0.0833333 feet

Common Rectangular Water Volumes

Length Width Depth Volume Approx. US Gallons
4 ft 3 ft 2 ft 24 cu ft 179.53 gal
8 ft 4 ft 2 ft 64 cu ft 478.75 gal
10 ft 5 ft 3 ft 150 cu ft 1,122.08 gal

Example Problems

Example 1: Find water volume in gallons

You have a rectangular space of water that is 10 ft long, 5 ft wide, and 3 ft deep.

V = 10 × 5 × 3 = 150 cu ft
150 ×7.48052 =1122.078 gal

The water volume is about 1,122.08 US gallons.

Example 2: Find missing depth

You have 478.75 gallons of water in a rectangular area that is 8 ft long and 4 ft wide.

V =478.75 ÷7.48052 ≈64 cu ft
D = 64 / (8 × 4) = 2 ft

The water depth is about 2 ft.

FAQ

Can this calculator be used for pools, tanks, and containers?

Yes. Select rectangular, vertical cylindrical or horizontal cylindrical geometry and enter inside dimensions. Cylinders are assumed to have flat ends. Oval, rounded-end, sloped and irregular containers require another model or measured calibration.

Which values are required?

Required inputs depend on shape and solve. Rectangular volume needs length, width and height; cylinders need diameter and height or length. Optional water depth can specify a partial fill. The depth solve additionally requires known water volume; horizontal-cylinder depth is found numerically.

Should I use total container depth or current water depth?

Use the current water depth if you want the actual amount of water present. Use the full inside depth only if the container is filled to the top.