Pool Salt Calculator
How much salt to add to a saltwater pool: enter the volume, current and target salt level (ppm) to get kg or pounds of salt and the number of bags — or how much water to replace if salt is too high.
How it works
salt (kg) = pool volume (L) × (target ppm − current ppm) ÷ 1,000,000 · US: salt (lb) = gallons × Δppm × 8.34 ÷ 1,000,000 · to lower: fraction to replace = 1 − target ÷ current
Salt concentration in parts per million is milligrams of salt per litre, so a litre of water at 3,200 ppm holds 3.2 g of salt. Multiply the litres in the pool by the increase you need and divide by a million to get kilograms (in US units the 8.34 factor converts gallons to pounds of water). Use pure, non-iodized pool salt (sodium chloride of 99% or higher), add it with the pump running, brush it to dissolve and wait 24 hours before re-testing. Salt only leaves the pool by splash-out, backwashing and draining, so lowering a high level means replacing part of the water.
Worked example
A new 50,000 L pool with no salt and a target of 3,200 ppm: 50,000 × 3,200 ÷ 1,000,000 = 160 kg of salt, which is 6.4 → 7 bags of 25 kg. Each 25 kg bag raises this pool by 500 ppm.
Sources: Hayward — AquaRite salt chlorination manual (salt chart) · CDC — Healthy Swimming: pool chemistry
Frequently asked questions
How much salt do I need for my pool?
About 3.2 kg per 1,000 litres to reach 3,200 ppm from zero — 160 kg for a 50,000 L pool. In US units, roughly 27 lb per 1,000 gallons, or 267 lb for 10,000 gallons.
What salt level should a saltwater pool have?
Most chlorine generators work at 2,700–3,400 ppm, with 3,000–3,200 ppm ideal; some low-salt systems use 1,500–2,500 ppm. Too little and the cell stops producing chlorine; too much can trigger a high-salt alarm and corrode metal.
How do I lower the salt level in my pool?
Drain part of the water and refill with fresh water. To go from 4,000 to 3,200 ppm you replace 1 − 3,200 ÷ 4,000 = 20% of the water.
How long after adding salt can I swim?
You can swim right away once it has dissolved, but wait about 24 hours with the pump running before turning the chlorinator back on and testing the salt level again.
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This calculator is for educational purposes. Double-check important results before acting on them.