Pool Salt Calculator (Litres & kg)

Metric version for UK, Australian, European and other pool owners. Enter your volume in litres to get kilograms of salt and bags to buy.

Salt to add

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Enter your pool volume to see results.

Bags to buy: —
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Pounds: —
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Metric pool salt formula

Because 1 litre of water weighs about 1 kg and 1 ppm is 1 mg per litre, metric salt maths needs no conversion factor:

Salt (kg) = Litres × (Target ppm − Current ppm) ÷ 1,000,000

If your volume is in cubic metres, multiply by 1,000 to get litres. A pool 8 m × 4 m with an average depth of 1.4 m holds 8 × 4 × 1.4 = 44.8 m³, or 44,800 litres.

Worked example

That 44,800-litre pool currently tests at 2,600 ppm and the generator manual recommends 3,200 ppm:

Increase = 3,200 − 2,600 = 600 ppm
Salt = 44,800 × 600 ÷ 1,000,000 = 26.9 kg
Bags = 26.9 ÷ 25 = 1.08 → 2 × 25 kg bags (or one 25 kg bag plus a 10 kg bag)

Metric pool salt chart

Kilograms of salt needed to raise salinity by the amount shown. Use the +3,200 ppm row for a freshly filled pool.

Kilograms of salt (and 25 kg bags) to raise salt level
Raise by	10,000 L	20,000 L	30,000 L	40,000 L	50,000 L	60,000 L	80,000 L	100,000 L	150,000 L
+500 ppm	5.0 kg 1 bag	10.0 kg 1 bag	15.0 kg 1 bag	20.0 kg 1 bag	25.0 kg 1 bag	30.0 kg 2 bags	40.0 kg 2 bags	50.0 kg 2 bags	75.0 kg 3 bags
+1,000 ppm	10.0 kg 1 bag	20.0 kg 1 bag	30.0 kg 2 bags	40.0 kg 2 bags	50.0 kg 2 bags	60.0 kg 3 bags	80.0 kg 4 bags	100 kg 4 bags	150 kg 6 bags
+1,500 ppm	15.0 kg 1 bag	30.0 kg 2 bags	45.0 kg 2 bags	60.0 kg 3 bags	75.0 kg 3 bags	90.0 kg 4 bags	120 kg 5 bags	150 kg 6 bags	225 kg 9 bags
+2,000 ppm	20.0 kg 1 bag	40.0 kg 2 bags	60.0 kg 3 bags	80.0 kg 4 bags	100 kg 4 bags	120 kg 5 bags	160 kg 7 bags	200 kg 8 bags	300 kg 12 bags
+2,500 ppm	25.0 kg 1 bag	50.0 kg 2 bags	75.0 kg 3 bags	100 kg 4 bags	125 kg 5 bags	150 kg 6 bags	200 kg 8 bags	250 kg 10 bags	375 kg 15 bags
+3,000 ppm	30.0 kg 2 bags	60.0 kg 3 bags	90.0 kg 4 bags	120 kg 5 bags	150 kg 6 bags	180 kg 8 bags	240 kg 10 bags	300 kg 12 bags	450 kg 18 bags
+3,200 ppm	32.0 kg 2 bags	64.0 kg 3 bags	96.0 kg 4 bags	128 kg 6 bags	160 kg 7 bags	192 kg 8 bags	256 kg 11 bags	320 kg 13 bags	480 kg 20 bags

See the printable chart for gallons and litres on one page.

Adding salt: the short version

Test salt, pH and alkalinity with an independent test kit.
Follow your manual — many recommend switching the chlorinator cell off while salt dissolves.
With the pump running, spread the salt around the shallow end and brush the floor.
Circulate for about 24 hours, retest, and add more only if needed.

Use pure pool salt (at least 99% sodium chloride, non-iodized, no anti-caking agents). If your reading is above target, salt can only be lowered by partial draining — see the dilution calculator. Not sure of your volume? Try the pool volume calculator.

FAQ

How much salt per 1,000 litres of pool water?

Every 1 kg of salt raises 1,000 litres (1 m³) by 1,000 ppm. So to reach 3,200 ppm from fresh water you need 3.2 kg per 1,000 litres — 160 kg for a 50,000-litre pool.

How many 25 kg bags do I need for a 50,000 litre pool?

From fresh water to 3,200 ppm: 50,000 × 3,200 ÷ 1,000,000 = 160 kg, which is 6.4 bags, so buy 7 × 25 kg bags (or add 6 and retest). A top-up from 2,500 to 3,200 ppm needs only 35 kg.

Is ppm the same as g/L or mg/L?

For pool water, 1 ppm ≈ 1 mg/L, so 3,200 ppm ≈ 3.2 g/L. Some generators and test kits in the UK, Europe and Australia display salinity in g/L or as a percentage; 3,200 ppm = 3.2 g/L = 0.32%.

Some generators ask for 4,000–6,000 ppm. Is that wrong?

Not necessarily. While many cells run around 2,700–3,400 ppm, some models — including several sold in Australia — are designed for higher salinity. Always use the figure in your own generator's manual and enter it as the target.