Pool Volume Calculator — Canada
Metric by default: metres in, litres out.
Pool volume formulas (gallons and litres)
- • Rectangle: Length × Width × Avg depth × 7.5 = US gallons (× 3.785 = litres)
- • Round: π × (Diameter ÷ 2)² × Depth × 7.5 = US gallons
- • Oval: π × (Length ÷ 2) × (Width ÷ 2) × Depth × 7.5 = US gallons
- • Kidney: 0.45 × (Wide lobe + Narrow waist) × Length × Depth × 7.5 (±10% estimate)
- • In metres: Length × Width × Avg depth × 1,000 = litres
Average depth = (shallow end + deep end) ÷ 2, measured at the water — not the wall top. Above-ground walls run 48"–52" but water sits ~6" lower.
Common Canadian pool sizes
| Type | Dimensions | Approx. volume |
|---|---|---|
| Round above-ground | 18 ft Ø × 4 ft water | ~7,600 gal (~28,800 L) |
| Round above-ground | 24 ft Ø × 4 ft water | ~13,600 gal (~51,500 L) |
| Oval above-ground | 18 × 33 ft × 4 ft water | ~10,600 gal (~40,100 L) |
| Small in-ground | 12 × 24 ft × 5 ft avg | ~10,800 gal (~40,900 L) |
| Medium in-ground | 16 × 32 ft × 5 ft avg | ~19,200 gal (~72,700 L) |
| Large in-ground | 20 × 40 ft × 5 ft avg | ~30,000 gal (~113,600 L) |
Pool volume FAQs
How do I calculate pool volume in Canada — gallons or litres?
Both work: measure in feet and multiply Length × Width × Average depth × 7.5 for US gallons, or measure in metres and multiply × 1,000 for litres. A 16 × 32 ft pool at 5 ft average depth holds about 19,200 gallons (≈72,700 litres). Always check which gallon your chemical label uses.
How much water does an above-ground round pool hold?
Use π × radius² × water depth (not wall height — water sits ~6" below the top rail). An 18 ft round pool at 4 ft of water holds about 7,600 gallons (≈28,800 litres); a 24 ft round holds about 13,600 gallons (≈51,500 litres).
Should I use average depth or deep-end depth?
Always average: (shallow + deep) ÷ 2, measured at the waterline. Using deep-end depth alone can overdose every chemical by up to 40%.
How does the kidney pool estimate work?
Use 0.45 × (wide lobe + narrow waist) × length × average depth — the industry-standard approximation (±10%). Add two-thirds of any dose, retest, then top up.
Why does pool volume matter for closing?
Winterizing chemicals, shock and algaecide all scale to your litres — guess the volume and you open to green water in spring. Calculate volume first, then follow our pool closing checklist and dose with our chemical, chlorine and salt calculators.