Pool volume and salinity calculator

This calculator does two jobs for pool owners. First, it works out your swimming pool’s volume from its dimensions, in cubic metres, litres, and US gallons. Second, for saltwater pools, it estimates how much pool salt you need to add to move from your current salinity to your target level in parts per million (ppm).

Why pool volume matters

Knowing your exact volume is essential for dosing every chemical correctly — chlorine, salt, pH adjusters, and algaecide are all added per unit of water. The volume is length × width × average depth; for pools that get deeper at one end, use the average of the shallow and deep depths.

Salt for saltwater pools

Saltwater chlorinators typically run best at around 2,700–3,400 ppm — always check your unit’s recommended level. Because salinity is measured in mg per litre, the salt required equals the volume in litres multiplied by the ppm increase, divided by a million. Add salt gradually, run the pump to circulate, and re-test before adding more. For unit conversions, see our volume converter.

Frequently asked questions

How much salt raises a pool by 1,000 ppm?

About 1 kg of salt per 1,000 litres of water raises salinity by 1,000 ppm. The calculator works out the exact amount for your pool.

Disclaimer: Estimates only. Always follow your chlorinator and chemical instructions and test your water regularly.