Pool Volume Calculator
Calculate swimming pool volume in US gallons, litres, cubic feet and cubic metres, then estimate a product amount for a user-entered ppm change.
Inputs
Chemical dose helper
Results
Enter dimensions and calculate to see the pool estimate.
How the Calculator Works
The calculator estimates surface area from the selected shape, multiplies by average water depth, and converts the volume to common pool units. Use measured inside dimensions at the waterline when possible. If the pool has a sloped floor, use the shallow and deep depths so the tool can use the average depth.
- Rectangle:
volume = length x width x average depth - Round:
volume = pi x radius² x average depth - Oval:
volume = pi x (length / 2) x (width / 2) x average depth - Kidney/irregular estimate:
volume = length x width x 0.45 x average depth - Conversions:
1 ft³ = 7.48052 US gal,1 m³ = 1000 L,1 US gal = 3.78541 L
Chemical Dose Assumptions
The dose helper is a conversion tool, not a treatment recommendation. It uses the water chemistry convention
that 1 ppm is approximately 1 mg/L in water. Product required is estimated from:
active grams = ppm change x litres / 1000, then
product = active grams / (strength percent / 100).
For liquids, the tool converts product mass to volume using the density you enter. Pool chemical products vary by formulation, freshness, label directions and local code requirements. Test the water first, follow the product label, never mix chemicals, and use a qualified pool professional for uncertain or commercial dosing. CDC pool chemical safety guidance also emphasizes label directions, training and avoiding incompatible mixes.
Safety reference: CDC Pool Chemical Safety.
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Example
A rectangular 32 ft by 16 ft pool with a 3.5 ft shallow end and 8 ft deep end has an average depth of 5.75 ft. Its estimated volume is about 22,023 US gallons, or 83,365 litres. A 1 ppm change requires about 83.4 grams of active ingredient before adjusting for product strength.
FAQs
Should I use total depth or water depth?
Use the actual water depth, not the wall height above the waterline. Small depth differences can change volume by hundreds of gallons.
What shape should I use for a freeform pool?
Use the kidney option for a rough freeform estimate, then compare against builder plans or a water-meter fill reading for higher accuracy.
Are UK gallons included?
The main result uses US gallons because pool product labels commonly use US gallons. Litres and cubic metres are also shown for metric planning.
Can I use this for salt or chlorine dosing?
Use it only as a unit conversion helper for a ppm change you have already decided from testing, product instructions, and applicable guidance.
Does this store my pool dimensions?
No. Calculations run in your browser. The page does not upload or track your inputs.
5 Fun Facts about Pool Volume
- One cubic foot holds about 7.48 US gallons. That conversion is why small measurement changes can move a pool estimate by hundreds of gallons.
- Average depth matters more than wall height. Sloped floors make shallow and deep measurements more useful than a single depth number.
- Oval pools use ellipse math. The surface area estimate comes from pi times half the length times half the width.
- Freeform pools are usually estimates. Benches, steps, shelves, and curved walls reduce or shift the true water volume.
- One ppm is about one milligram per litre. That simple water-chemistry convention makes pool dose conversions easier to check.
Limits
Pool volumes are estimates unless measured during filling. Curved corners, benches, steps, sun shelves, spas, sloped sidewalls and unusual deep-end geometry can shift the real volume. Chemical results are rounded planning conversions and are not a substitute for testing, label directions or professional service.