How pool volume is calculated
Each pool shape uses a specific formula. For a rectangular pool: length × width × average depth. For a circular pool: π × radius² × depth. For an oval pool: π/4 × length × width × depth. For a kidney-shaped pool: (widest width + narrowest width) ÷ 2 × length × 0.89 × depth — the 0.89 factor accounts for the concave section.
The calculator uses average depth, not deep-end depth. Add your shallow-end depth and your deep-end depth together and divide by two. A pool that's 1.0 m at the shallow end and 2.0 m at the deep end has an average depth of 1.5 m.
Why does pool volume matter?
Every pool chemical product — chlorine, pH adjusters, algaecide, clarifier, salt — is dosed per 10,000 litres (10 kL). Getting your volume right means you're not under-dosing (leaving the pool unsafe) or over-dosing (wasting money and potentially causing irritation).
Your pool volume is also important for pump sizing and turnover rate. For good water quality, your pump should turn over the full pool volume every 6–8 hours. A 50,000 L pool needs a pump capable of at least 6,250 L/hr (6.25 kL/hr).
Common AU pool chemical dosing guide
- Granular chlorine (calcium hypochlorite 70%) — 170 g per 10,000 L to raise free chlorine by 1 ppm.
- Liquid chlorine (sodium hypochlorite 12.5%) — 800 mL per 10,000 L to raise free chlorine by 1 ppm.
- pH Up (sodium carbonate) — 100 g per 10,000 L to raise pH by 0.1.
- pH Down (sodium bisulphate) — 100 g per 10,000 L to lower pH by 0.1.
- Salt (for chlorinators) — 200 kg per 10,000 L to raise salinity by 1,000 ppm. Most AU chlorinators require 3,000–5,000 ppm.
- Stabiliser (cyanuric acid) — 90 g per 10,000 L to raise CYA by 10 ppm.
How often should I test my pool water?
Test free chlorine and pH at least twice a week during summer and weekly in winter. Use a good-quality test kit or take a water sample to your local pool shop — most will test it for free and advise on dosing. In QLD and northern NSW, the hot summer sun burns through chlorine faster; daily testing is sensible during heatwaves.
Pool volume calculator — frequently asked questions
How do I calculate the volume of my pool?
For a rectangular pool, multiply length × width × average depth. For a pool with a shallow and deep end, average depth is (shallow depth + deep depth) ÷ 2. A 8 m × 4 m pool with an average depth of 1.4 m holds 44,800 litres. The calculator handles rectangular, circular and irregular shapes.
How much chlorine do I need to shock a pool?
A standard shock dose is typically 170–200 grams of granular chlorine (calcium hypochlorite) per 10,000 litres of pool water. The calculator gives you a starting dose based on your pool volume — always test and adjust based on your actual water chemistry readings.
How often should I test my pool water in Queensland?
At least twice a week during Queensland's summer — higher temperatures and UV intensity consume chlorine faster and algae grows more aggressively. In winter, once a week is generally sufficient. After heavy rain, test immediately as storm runoff can significantly alter pH and chlorine levels.
What is the ideal chlorine level for a pool in Australia?
Free chlorine should be maintained between 1–3 ppm (parts per million) for a standard chlorinated pool. In Queensland's warmer months, staying toward the 2–3 ppm end provides a better buffer against rapid chlorine depletion. pH should sit between 7.2 and 7.6 — outside this range, chlorine becomes significantly less effective.
How much salt do I need for a salt water pool?
Most Australian salt water chlorinator systems require a salt level of 3,000–4,000 ppm (around 3–4 kg of salt per 1,000 litres of water for initial setup). For a 50,000 litre pool being filled from scratch, that's approximately 150–200 kg of pool salt. The calculator estimates the starting salt dose based on your pool volume.