# Pool Salt Calculator

URL: https://speedycalculator.com/calculators/everyday-life/pool-salt/
Last updated: 2026-10-25

> The pool salt calculator works out how many pounds or kilograms of salt (and 40 lb bags) to add to a saltwater pool to reach the target salt level, or how much water to drain if the level is too high.

## Inputs

- Pool volume (US gal, L, UK gal)
- Current salt level (ppm)
- Target salt level (ppm)
- Salt bag size

## Results

- Salt to add
- Bags of salt
- Water to drain and refill (if too salty)

## Formula

```
Salt to add (lb) = gallons × 8.34 × (target − current ppm) ÷ 1,000,000
If too high: water to replace = volume × (1 − target ÷ current)
```

## Explanation

Salt chlorine generators need the salt level within a set range – usually 2,700–3,400 ppm with an ideal of about 3,200 ppm. Too little and the cell cannot make enough chlorine; too much can corrode equipment. Add pool-grade salt with the pump running and retest after 24 hours.

### How to use the Pool Salt Calculator

- **Pool volume**
- **Current salt level**
- **Target salt level**
- **Salt bag size**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the pool volume, your current salt reading and the target level for your chlorinator.

### Tips

- Use the figures from your own bills and product labels – prices and appliance ratings vary widely.
- Look at yearly totals: small daily costs add up and make it easier to compare options.
- Round quantities up to whole packs, rolls or bulbs when you shop.
- Re-check the numbers when prices change; most results scale directly with the unit price.

### Common mistakes to avoid

- Confusing watts (power) with watt-hours or kilowatt-hours (energy).
- Comparing prices without bringing them to the same unit first.
- Ignoring one-off costs such as installation, delivery or replacement parts.

### Inputs explained

FieldWhat to enterPool volumeUnits: US gal, L, UK galCurrent salt levelIn ppmTarget salt levelIn ppmSalt bag sizeChoose one: 40 lb, 50 lb, 25 kg, 20 kg

### What each result means

- **Salt to add** = max([Target salt level] - [Current salt level], 0)×[Pool volume]×1000÷1000000
- **Bags of salt** = ceil([Salt to add]÷[Salt bag size] - 0.000001)

### Example values

How the main result changes when **Pool volume** changes and everything else stays at the example values above:

Pool volume (US gal)Salt to add (lb)7,50050.111,25075.115,000100.118,750125.222,500150.230,000200.3

## Worked example

Inputs — Pool volume: 15,000 US gal; Current salt level: 2,400 ppm; Target salt level: 3,200 ppm; Salt bag size: 40 lb.

Results — **Salt to add = 100.1 lb**; Bags of salt = 3; Water to drain and refill (if too salty) = 0 US gal.

## FAQ

**How much salt does a pool need?**
About 30 lb per 1,000 gallons to raise from 0 to 3,600 ppm; to raise 800 ppm in a 15,000 gal pool, about 100 lb.

**What salt level should a saltwater pool have?**
Usually 2,700–3,400 ppm; check your chlorinator's manual (many recommend 3,200 ppm).

**How do I lower salt in a pool?**
Drain part of the water and refill with fresh water.

**What formula does the Pool Salt Calculator use?**
Salt to add (lb) = gallons × 8.34 × (target − current ppm) ÷ 1,000,000.