# Pool Calculator

URL: https://speedycalculator.com/calculators/construction/pool-volume/
Last updated: 2026-10-25

> The pool calculator works out the water volume of rectangular, round, oval and kidney-shaped pools with a shallow and deep end, the cost of filling it and how long the fill takes with a hose.

## Inputs

- Pool shape
- Length (ft, m, in, yd, cm)
- Width (kidney: wide end A) (ft, m, in, yd, cm)
- Kidney narrow end B (ft, m, in, yd, cm)
- Shallow end depth (ft, m, in, yd, cm)
- Deep end depth (ft, m, in, yd, cm)
- Water price (/1000 gal, /m³)
- Fill flow rate (gpm, L/min, gph, m³/h, ft³/s, L/s)

## Results

- Surface area
- Average depth
- Pool volume
- Weight of water
- Cost to fill
- Time to fill

## Formula

```
Average depth = (shallow + deep) ÷ 2
Volume = surface area × average depth
Kidney area ≈ 0.45 × (A + B) × L; oval area = π/4 × L × W
```

## Explanation

You need the pool volume to dose chemicals correctly, size the pump and filter, and estimate the cost and time to fill it. Pools with a sloping floor are approximated by their average depth.

### How to use the Pool Calculator

- **Pool shape**
- **Length**
- **Width (kidney: wide end A)**
- **Kidney narrow end B**
- **Shallow end depth**
- **Deep end depth**
- **Water price**
- **Fill flow rate**
- Every result field is editable: type into **Pool volume** and **Deep end depth** plus every other field update to match.

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

### How it works

Choose the pool shape and enter its dimensions, shallow and deep end depths, the price of water and the flow of your hose or fill line.

### Tips for an accurate estimate

- Measure inside dimensions of tanks and pools – wall thickness can change the volume noticeably.
- Use the average depth for pools with a sloping floor.
- Remember the weight: water weighs about 8.34 lb per US gallon (1 kg per litre), so large volumes need solid support.
- Check whether a figure is in US gallons, imperial gallons or litres before ordering chemicals or equipment.

### Common mistakes to avoid

- Using wall height instead of water depth for above-ground pools.
- Assuming a horizontal tank's volume is proportional to the liquid level – it is not.
- Mixing up flow units such as GPM, GPH and litres per minute.

### Inputs explained

FieldWhat to enterPool shapeChoose one: Rectangle, Round (length = diameter), Oval, KidneyLengthUnits: ft, m, in, yd, cmWidth (kidney: wide end A)Units: ft, m, in, yd, cmKidney narrow end BUnits: ft, m, in, yd, cmShallow end depthUnits: ft, m, in, yd, cmDeep end depthUnits: ft, m, in, yd, cmWater priceUnits: /1000 gal, /m³Fill flow rateUnits: gpm, L/min, gph, m³/h, ft³/s, L/s

### What each result means

- **Average depth** = ([Shallow end depth] + [Deep end depth])÷2
- **Pool volume** = [Surface area]×[Average depth]
- **Weight of water** = [Pool volume]×1000
- **Cost to fill** = [Pool volume]×[Water price]
- **Time to fill** = [Pool volume]÷[Fill flow rate]

### Example values

How the main result changes when **Deep end depth** changes and everything else stays at the example values above:

Deep end depth (ft)Pool volume (US gal)414,363618,193822,0231025,8531229,6831637,343

## Worked example

Inputs — Pool shape: Rectangle; Length: 32 ft; Width (kidney: wide end A): 16 ft; Kidney narrow end B: 10 ft; Shallow end depth: 3.5 ft; Deep end depth: 8 ft; Water price: $5 /1000 gal; Fill flow rate: 10 gpm.

Results — Surface area = 512 ft²; Average depth = 5.75 ft; **Pool volume = 22,023 US gal**; Weight of water = 91.9 US ton; Cost to fill = $110.11; Time to fill = 36.7 h.

## FAQ

**How many gallons is a 16 × 32 pool?**
With 3½ ft to 8 ft depth (average 5.75 ft): 512 ft² × 5.75 × 7.48 ≈ 22,000 gallons.

**How long does it take to fill a pool?**
At 10 gpm from a garden hose, about 36 hours for 22,000 gallons.

**Why do I need the pool volume?**
Chemical doses, heater sizing and pump turnover are all based on gallons.

**What formula does the Pool Calculator use?**
Average depth = (shallow + deep) ÷ 2.