How is the volume of a pool worked out?

Length times width times the average of the end depths for a rectangular footprint with uniform depth or a linear slope. A 10 m by 5 m pool linearly sloping from 1 m to 2 m has average depth 1.5 m and geometric volume 75 m³, or 75,000 litres. Steps, benches, irregular outlines and curved depth profiles need a different model.

My pool is the same depth all over. What do I type?

The same depth in both the shallow end and the deep end fields. The average of two equal numbers is that number, so a 10 m by 5 m pool 1.5 m deep throughout gives the same 75 m³ as one sloping from 1 m to 2 m.

What about an oval or a round pool?

Pick Oval pool and enter the full length and width of an elliptical footprint and both end depths. The model is π × (length/2) × (width/2) × average depth, with a uniform or linear depth profile. A circle uses equal length and width: a 4.5 m round pool at uniform 1.2 m depth holds about 19,085 litres. Stadium outlines and arbitrary pool outlines are not ellipses.

Which gallon does the calculator use?

Both US gallons and UK gallons have their own labelled rows. A US gallon is 3.785411784 litres and a UK gallon is 4.54609 litres, so the same volume has different numeric gallon values. Litres and cubic units are also shown. These are conversions of the supplied geometric volume, not a dosing or pump-sizing calculation.

Can I measure in feet?

Yes. Switch the unit to ft and type the sides in feet; the volume comes out in cubic feet with the litres and gallons rows under it. A 20 ft by 10 ft pool from 3 ft to 6 ft deep is 900 cubic feet, which is 25,485 litres or about 6,732 US gallons, because a cubic foot holds 7.48 US gallons.

How are measurements, units and saved work handled?

Choose the measured unit before typing; changing it reinterprets bare numbers rather than converting them. Decimal and scientific numbers, complete comma groups such as 1,200, numeric fractions such as 3/4 and mixed numbers such as 2 1/2 are accepted; written unit suffixes and expressions are not. Switching radius and diameter converts the current measurement to preserve the shape. Saved strings restore without writing defaults. Deliberate edits preserve independent newer saved fields, and malformed records are left intact. Results, full tank capacity and conversions must fit the supported numeric range. The visible result summary is selectable if the clipboard is unavailable.

Pool Volume Calculator

Type your pool's length, width and the depth at each end, in metres or feet, and read how much water it holds in litres, US gallons and UK gallons at once. Rectangular pools open here; switch to Oval pool for an oval or round one, and the formula used is printed with the working under it.

Cylinder · π r² h0.942478m³942.478 L · 248.976 US gal · 207.316 UK gal

Shape

Measure

Radius (m)

Height (m)

Unit

A drum, can or straight pipe: use the inner radius or diameter for capacity. Height is perpendicular to the circular end, including for an oblique cylinder; it is not a slanted axis length. The drawing is schematic. Choose the measured unit before typing; changing it reinterprets the numbers.

Result summary

Cylinder, radius 0.5 m, height 1.2 m
0.942477796077 m³
The working: π × 0.5² × 1.2 = 0.942477796077 volume, in m³
Litres: 942.477796077 L
US gallons: 248.976293692 US gal
UK gallons: 207.316132342 UK gal
Cubic feet: 33.2832892609 ft³
Cubic yards: 1.23271441707 yd³
Cubic inches: 57,513.5238428 in³

The workingvolume, in m³
π × 0.5² × 1.2 = 0.942477796077
LitresL
942.477796077
US gallonsUS gal
248.976293692
UK gallonsUK gal
207.316132342
Cubic feetft³
33.2832892609
Cubic yardsyd³
1.23271441707
Cubic inchesin³
57,513.5238428

The formula is on the stage, and the working is the first row. Every answer here is one textbook formula with your numbers put in, printed so you can check it: a cylinder is π r² h, a sphere is (4/3) π r³, a pool is length times width times the average of its two depths. The horizontal tank uses the circular-segment model with stable arithmetic for a partial fill, so half way up is exactly half and a quarter of the way up is less than a quarter, because the bottom of a circle is narrow. Conversions use exact definitions: a litre is 1,000 cm³, a US gallon is 231 cubic inches and a UK gallon is 4.54609 litres. Results are rounded; drawings are schematic. No arbitrary outlines, end caps, tapered tanks, pressure, chemical dosing, reverse dimensions, subtraction or shared surface-area result is computed here.

Common questions

How is the volume of a pool worked out?: Length times width times the average of the end depths for a rectangular footprint with uniform depth or a linear slope. A 10 m by 5 m pool linearly sloping from 1 m to 2 m has average depth 1.5 m and geometric volume 75 m³, or 75,000 litres. Steps, benches, irregular outlines and curved depth profiles need a different model.
My pool is the same depth all over. What do I type?: The same depth in both the shallow end and the deep end fields. The average of two equal numbers is that number, so a 10 m by 5 m pool 1.5 m deep throughout gives the same 75 m³ as one sloping from 1 m to 2 m.
What about an oval or a round pool?: Pick Oval pool and enter the full length and width of an elliptical footprint and both end depths. The model is π × (length/2) × (width/2) × average depth, with a uniform or linear depth profile. A circle uses equal length and width: a 4.5 m round pool at uniform 1.2 m depth holds about 19,085 litres. Stadium outlines and arbitrary pool outlines are not ellipses.
Which gallon does the calculator use?: Both US gallons and UK gallons have their own labelled rows. A US gallon is 3.785411784 litres and a UK gallon is 4.54609 litres, so the same volume has different numeric gallon values. Litres and cubic units are also shown. These are conversions of the supplied geometric volume, not a dosing or pump-sizing calculation.
Can I measure in feet?: Yes. Switch the unit to ft and type the sides in feet; the volume comes out in cubic feet with the litres and gallons rows under it. A 20 ft by 10 ft pool from 3 ft to 6 ft deep is 900 cubic feet, which is 25,485 litres or about 6,732 US gallons, because a cubic foot holds 7.48 US gallons.
How are measurements, units and saved work handled?: Choose the measured unit before typing; changing it reinterprets bare numbers rather than converting them. Decimal and scientific numbers, complete comma groups such as 1,200, numeric fractions such as 3/4 and mixed numbers such as 2 1/2 are accepted; written unit suffixes and expressions are not. Switching radius and diameter converts the current measurement to preserve the shape. Saved strings restore without writing defaults. Deliberate edits preserve independent newer saved fields, and malformed records are left intact. Results, full tank capacity and conversions must fit the supported numeric range. The visible result summary is selectable if the clipboard is unavailable.

Rounded browser arithmetic for the dimensions and ideal shapes shown; pools assume a uniform or linear depth profile. Drawings are schematic. A US gallon is 231 cubic inches and a UK gallon is 4.54609 litres.