Pool Salt Calculator

Pool salt calculator for saltwater pools: enter your volume and current salt reading to get the pounds and kilograms of salt to add, rounded up to whole 40 lb or 25 kg bags.

Quick answer

Salt to add = (target ppm − current ppm) × pool volume, and 1 ppm is 1 gram per 1,000 litres. A 15,000 US gallon pool going from 2,400 to 3,200 ppm needs 100.2 lb (45.43 kg) — 3 bags of 40 lb salt, or 2 bags of 25 kg. Salt cannot be removed afterwards, only diluted, so aim just under your generator’s target rather than over it.

Your Pool

Pool volume

Measured in

Not sure? The pool volume calculator works it out from your pool’s shape and measurements, and this page picks the answer up automatically.

Current salt level (ppm)

From a test strip, a meter, or your generator’s display. A brand-new fill reads close to 0.

Target salt level (ppm)

Most generators want 2,700–3,400 ppm. Check your unit’s manual — the number that matters is the one it prints. Running well above its range shortens cell life and is harder on metal fittings, and salt only comes back out with the water.

Salt to Add

100.2 lb

of pool salt

45.43 kg

the same dose, metric

3 bags

at 40 lb a bag

2 bags

at 25 kg a bag

The weight is rounded up and the bag count comes from that figure, because half a bag of salt is not something you can buy. Aim to land a little under target rather than over it: the last bag is the one that overshoots, and the only way back down is draining water.

Broadcast it across the shallow end with the pump running and brush it toward the main drain. Never pour salt into the skimmer — undissolved crystals reaching the pump, heater or cell is how this job turns into a repair.

Then leave it a full circulation cycle, around 24 hours, before you test again. Salt reads low until it has dissolved and mixed, and dosing a second time on an unmixed reading is exactly how pools end up over target — which, as above, only water can undo.

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What a Salt Chlorine Generator Actually Wants

A saltwater pool is a chlorine pool. The generator passes water over a cell that splits dissolved salt into chlorine, the chlorine sanitizes, and it recombines into salt again — which is why the salt level barely moves from month to month and why nothing in the pool “uses it up”. The number you are managing is the salinity the cell needs to work at all: too low and it produces little or no chlorine while the water looks fine for a few days, too high and it warns, shuts down, or wears out faster.

Most residential units sit between 2,700 and 3,400 ppm, and 3,200 is a reasonable middle target — but brands really do differ, so the manual is the authority and this calculator lets you type whatever it says. For scale, a pool runs at roughly a tenth of the salinity of seawater. Can you taste it? Some people can. Sensitivity varies enormously: the most sensitive palates notice salt from around 1,000 ppm, most people somewhere between 3,500 and 6,000, so at a 3,200 ppm target a few of your swimmers will register something — usually described as the water feeling soft rather than tasting salty. Drift above target and more of them will.

Why the Answer Comes Back in Bags

The chemistry is the easy part. One part per million is one milligram per litre, so raising a pool by 1 ppm takes one gram of salt per 1,000 litres, and the whole dose is that multiplied by how far the reading has to move. What actually decides your afternoon is the packaging: salt is sold in 40 lb bags in the US and 25 kg bags in most of Europe, and you cannot buy 2.5 of them. So the result is rounded up to whole bags in both markets, and the advice attached to it is to aim a little under target — an extra bag is far easier to add next week than to take out ever.

Salt Only Goes One Way

There is no chemical that lowers salinity, no filter that catches it, and no amount of running the generator that consumes it. If you overshoot, the only lever is replacing water: drop from 4,000 to 3,200 ppm and you are replacing 20% of the pool. Enter a current reading above your target and the calculator switches to exactly that answer — the percentage and the actual volume, in gallons and litres.

Salt does leave on its own, but only inside water that leaves: splash-out, backwashing a sand filter, a rain overflow, a leak, or a winter drain-down. Evaporation leaves it all behind. So the honest maintenance rhythm is to test after anything that removed water, and not to bother otherwise.

Adding It Without Damaging Anything

Broadcast the salt across the shallow end with the pump running, then brush it toward the main drain so it dissolves in moving water. Do not pour it into the skimmer: undissolved crystals travelling to the pump, heater or cell is how a fifteen-minute job becomes a repair. Give it a full turnover, around 24 hours, before re-testing — salt reads low until it has mixed, and a second dose based on an unmixed reading is the single most common way pools end up over target.

The Rest of the Water Still Needs Watching

Salt is the one reading a saltwater pool adds; it does not replace the others. The generator makes chlorine but it does not manage stabilizer, and a saltwater pool without enough cyanuric acid burns its chlorine off in sunlight faster than the cell can make it. Generators also push pH up over time, which is what the pool chemical calculator is for. And all of it starts from the volume — if you have not measured yours, work it out from your pool’s shape first, or start at the pool calculators hub.

How Much Salt, By Pool Size

The four columns are the situations people actually turn up in: a small top-up after rain, a mid-season correction, a pool that has been diluted hard by a drain-and-refill, and a fresh fill starting from zero. Both tables are computed by the same functions the calculator runs.

Salt to add — US pools, 40 lb bags

Pool size	+400 ppm	+700 ppm	+1,200 ppm	+3,200 ppm
10,000 gal	33.4 lb (1 bag)	58.5 lb (2 bags)	100.2 lb (3 bags)	267.1 lb (7 bags)
15,000 gal	50.1 lb (2 bags)	87.7 lb (3 bags)	150.3 lb (4 bags)	400.6 lb (11 bags)
20,000 gal	66.8 lb (2 bags)	116.9 lb (3 bags)	200.3 lb (6 bags)	534.2 lb (14 bags)
25,000 gal	83.5 lb (3 bags)	146.1 lb (4 bags)	250.4 lb (7 bags)	667.7 lb (17 bags)

+3,200 ppm is a fresh fill starting from zero; +400 ppm is the size of correction rain and backwashing usually call for. Weights are rounded up to a tenth of a pound and the bag count is taken from that figure, so every cell divides into its own whole 40 lb bags. Where whole bags overshoot the dose by a wide margin — the 200.3 lb cell buys 6 bags, 240 lb — add part of the last bag, wait a full turnover, and re-test rather than pouring all of it in.

Salt to add — metric pools, 25 kg bags

Pool size	+400 ppm	+700 ppm	+1,200 ppm	+3,200 ppm
40,000 L	16 kg (1 bag)	28 kg (2 bags)	48 kg (2 bags)	128 kg (6 bags)
60,000 L	24 kg (1 bag)	42 kg (2 bags)	72 kg (3 bags)	192 kg (8 bags)
80,000 L	32 kg (2 bags)	56 kg (3 bags)	96 kg (4 bags)	256 kg (11 bags)
100,000 L	40 kg (2 bags)	70 kg (3 bags)	120 kg (5 bags)	320 kg (13 bags)

Same chemistry, different packaging: 1 ppm is 1 gram of salt per 1,000 litres, and bags round up to whole 25 kg sacks.

How to work out how much salt your pool needs

Three numbers in — volume, current reading, target — and a bag count out. The fourth step is the one that decides whether it goes well.

Put in your pool volume
Gallons or litres, whichever your test kit and chemical labels speak. If you have already used the pool volume calculator on this site, the field arrives filled in with that number — the two pages share it through your own browser, not a server.
Enter the salt level you measured
Use a salt test strip, a digital salinity meter, or the reading on your chlorine generator. A brand-new fill starts near zero. If the generator is complaining about low salt, trust a strip over the cell — a scaled or aging cell reads low and will happily talk you into overdosing.
Set the target your generator asks for
Most units want somewhere between 2,700 and 3,400 ppm, and the calculator opens at 3,200. The number that actually matters is the one printed in your unit's manual, so use that when they disagree.
Buy the bags, then add it properly
The result gives pounds and kilograms and rounds up to whole 40 lb or 25 kg bags. Broadcast the salt over the shallow end with the pump running, brush it toward the main drain, and wait a full circulation cycle — around 24 hours — before testing again.

Frequently Asked Questions

How much salt do I add to a 10,000 gallon pool?

It depends entirely on where the reading is now, because salt is not consumed — you are topping up, not refilling. Bringing a 10,000 gallon pool from a fresh fill at 0 up to 3,200 ppm takes 267.1 lb (121.14 kg), which is 7 bags of 40 lb salt. The far more common job is a small correction after rain or backwashing: 2,800 up to 3,200 ppm is only 33.4 lb, or 1 bag.

How many bags of salt does a pool need?

A 40 lb bag carries about 18 kg of salt, so what it moves the reading by depends on the pool. Filling a 20,000 gallon pool from zero to 3,200 ppm takes 14 bags; a 700 ppm mid-season correction on the same pool takes 3 bags. Buy the round-up, but do not necessarily pour it: the last bag is the one that overshoots, and there is no way back down except draining water. Where the gap is wide, add part of it and re-test.

Can I remove salt from my pool?

No. Nothing consumes salt and no chemical removes it — not the chlorine generator, not shock, not time. The only way down is dilution: drain part of the pool and refill with fresh water. Dropping from 4,000 to 3,200 ppm means replacing about 20% of the water, and the calculator above works out the exact share and volume for your pool if you enter a current reading above your target.

What happens if the pool salt level is too high?

Most chlorine generators show a high-salt warning and some shut the cell down to protect themselves, so the pool quietly stops being chlorinated — which is the part that actually costs you, because algae does not wait. Sustained high salinity is also harder on metal fittings, ladders, heaters and stone coping. It is not a swimmer-safety issue at these levels, but it is increasingly a noticeable one: sensitivity to salt varies enormously, the most sensitive people pick it up from around 1,000 ppm, and most notice something somewhere between 3,500 and 6,000. The further over target you drift, the more swimmers will say the water tastes of it. Fix it by replacing water, in stages.

What salt level should a saltwater pool be?

The generator sets the number, not the water. Most residential units are happiest between 2,700 and 3,400 ppm, with 3,200 a common middle target — but brands genuinely differ, and running below your unit's minimum means it makes little or no chlorine while reporting that everything is fine. Read the manual once and write the number on the equipment pad.

How long does pool salt take to dissolve?

Fine pool salt broadcast over the shallow end and brushed toward the main drain with the pump running is usually gone within a few hours, but the water needs a full circulation cycle — call it 24 hours — before a test reads the true level. Testing early is the classic way to over-salt a pool: the strip reads low, you add another bag, and then the only fix is draining. Never pour salt into the skimmer, where undissolved crystals reach the pump, heater and cell.

Does salt get used up in a saltwater pool?

No. The generator splits salt into chlorine, the chlorine does its job, and it recombines back into salt — the cycle returns what it borrows. Salt only leaves in water that leaves: splash-out, backwashing, a rain overflow, a leak, or a partial drain. Evaporation leaves every gram behind, so topping the water level up after a hot week needs no salt at all, and a pool that keeps dropping is telling you about a leak rather than about chemistry.

Can I use water softener salt instead of pool salt?

What matters is that it is sodium chloride and nothing else. Pool salt is sold fine-grained and non-iodized, with as little else in it as the grade allows, precisely because it dissolves fast and adds nothing you would then have to remove. Avoid anything with iodine, anti-caking agents or mineral content, and note that coarse pellets dissolve slowly enough to sit on the floor and stain a vinyl liner. Several generator manufacturers specify a salt grade in the manual and tie the cell warranty to it, which settles the question for your pool.

Does the calculator work in litres and kilograms?

Yes, both directions. Switch the volume field to litres and every answer still comes back in pounds and kilograms side by side, with bag counts for 40 lb bags and 25 kg bags, because a pool in Europe and a pool in Arizona get chemicals in different packaging and the same chemistry.