# Pool volume and tank capacity calculator

> Pool volume in gallons, litres and m³ for rectangular, round or oval pools and water tanks, with fill time and the chlorine dose to raise ppm.

Version interactive : https://www.calcopenly.com/fr/construction/pool-volume-calculator
Sujet : Calculatrices pour la construction et la maison

Volume is the water's surface area times its depth: length × width × average depth for a rectangular pool with a sloping floor, π × radius² × depth for a round pool or upright tank, and π/4 × length × width × depth for an oval. The result is given in litres, US gallons and cubic metres, and the fill time is the volume divided by the flow rate.

The default 10 × 5 m pool, 1 m deep at one end and 2 m at the other, holds 75,000 L (19,813 US gallons) and takes about 42 hours to fill at 30 L/min. Raising its free chlorine by 2 ppm needs 150 g of available chlorine, which is 1.2 L of 12.5% liquid.

One ppm is 1 mg of available chlorine per litre, and the product amount is that mass divided by its strength. Liquid strength is read as trade percent, grams per 100 mL, so 12.5% liquid carries 125 g per litre.

## Données

- **Shape** (options : Rectangular pool, Round pool, Oval pool, Cylindrical tank (upright), Rectangular tank)
- **Longueur**
- **Largeur**
- **Diamètre**
- **Shallow end depth**
- **Deep end depth**
- **Water depth**
- **Fill rate**: A garden hose gives roughly 20–40 L/min (5–10 gal/min).
- **Raise free chlorine by**
- **Chlorine product** (options : Liquid chlorine 12.5%, Liquid chlorine 10%, Cal-hypo 65% (granular), Cal-hypo 73% (granular), Dichlor 56% (granular), Trichlor 90% (tablets))

## Résultats

- Water volume (L) — résultat principal
- Water volume (US gal)
- Water volume (m³)
- Time to fill
- Liquid chlorine to add (L)
- Liquid chlorine to add (US fl oz)
- Chlorine product to add (g)
- Chlorine product to add (oz)

## Formule

$$
V_{\text{rect}} = \ell w \tfrac{d_1 + d_2}{2},\ V_{\text{round}} = \pi r^2 d,\ V_{\text{oval}} = \tfrac{\pi}{4}\ell w d,\qquad m_{\text{Cl}} = \text{ppm} \times V_{\text{L}}\ \text{mg}
$$

## Exemples détaillés

### 10 × 5 m pool, 1 m to 2 m deep, +2 ppm with 12.5% liquid

- Shape: Rectangular pool
- Longueur: 10 m
- Largeur: 5 m
- Shallow end depth: 1 m
- Deep end depth: 2 m
- Fill rate: 30 L/min
- Raise free chlorine by: 2 ppm
- Chlorine product: Liquid chlorine 12.5%
- **Water volume: 75,000 L**
- **Water volume: 19,812.9 US gal**
- **Time to fill: 1 d 17 h 40 min**
- **Liquid chlorine to add: 1.2 L**
- **Liquid chlorine to add: 40.58 US fl oz**
- Source de vérification : Python decimal: 10 × 5 × 1.5 = 75 m³; 75,000 L ÷ 30 L/min = 2,500 min; 2 mg/L × 75,000 L = 150 g ÷ 125 g/L = 1.2 L

### 24 ft round pool, 4 ft deep, 9 gal/min hose, +1 ppm cal-hypo 65%

- Shape: Round pool
- Diamètre: 24 ft
- Water depth: 4 ft
- Fill rate: 9 gal/min
- Raise free chlorine by: 1 ppm
- Chlorine product: Cal-hypo 65% (granular)
- **Water volume: 13,536.4 US gal**
- **Time to fill: 1 d 1 h 4 min 2 s**
- **Chlorine product to add: 78.8 g**
- **Chlorine product to add: 2.78 oz**
- Source de vérification : Python decimal: π × 12² × 4 ft³ = 13,536 US gal; 51,241 g ÷ 1000 ÷ 0.65 = 78.8 g (Clean Pool Math: 2.1 oz per 10,000 gal·ppm → 2.8 oz)

### Upright tank 1 m across, 1.2 m of water, 10 L/min

- Shape: Cylindrical tank (upright)
- Diamètre: 1 m
- Water depth: 1.2 m
- Fill rate: 10 L/min
- Raise free chlorine by: 0 ppm
- Chlorine product: Liquid chlorine 12.5%
- **Water volume: 942.5 L**
- **Time to fill: 1 h 34 min 14 s**
- **Liquid chlorine to add: 0 L**
- Source de vérification : Python decimal: π × 0.5² × 1.2 = 0.942478 m³; 942.48 L ÷ 10 L/min = 94.25 min

### 30 × 15 ft oval, 4 ft deep, +3 ppm with 10% liquid

- Shape: Oval pool
- Longueur: 30 ft
- Largeur: 15 ft
- Water depth: 4 ft
- Fill rate: 30 L/min
- Raise free chlorine by: 3 ppm
- Chlorine product: Liquid chlorine 10%
- **Water volume: 10,575.3 US gal**
- **Liquid chlorine to add: 1.201 L**
- Source de vérification : Python decimal: π/4 × 30 × 15 × 4 = 1,413.7 ft³ = 10,575 gal (industry shortcut L × W × D × 5.9 gives 10,620)

### Edge: 2 × 1.5 × 1 m tank, +5 ppm dichlor

- Shape: Rectangular tank
- Longueur: 2 m
- Largeur: 1.5 m
- Water depth: 1 m
- Fill rate: 20 L/min
- Raise free chlorine by: 5 ppm
- Chlorine product: Dichlor 56% (granular)
- **Water volume: 3,000 L**
- **Time to fill: 2 h 30 min**
- **Chlorine product to add: 26.8 g**
- Source de vérification : Hand calculation: 3 m³ = 3,000 L ÷ 20 L/min = 150 min; 5 mg/L × 3,000 L = 15 g ÷ 0.56 = 26.79 g

## Questions

### How do you calculate pool volume in gallons?

Multiply length × width × average depth in feet to get cubic feet, then multiply by 7.48, the number of US gallons in a cubic foot (1,728 ÷ 231 cubic inches). A 30 × 15 ft pool averaging 5 ft deep holds 2,250 ft³, or 16,831 gallons. For a round pool use π × radius² × depth: 24 ft across and 4 ft deep holds 13,536 gallons.

### How many litres of water are in a pool?

Multiply length × width × average depth in metres, then by 1,000, since a cubic metre holds 1,000 litres. A 10 × 5 m pool sloping from 1 m to 2 m has an average depth of 1.5 m, so it holds 75 m³, or 75,000 L. A round pool 5 m across with 1.2 m of water holds π × 2.5² × 1.2 = 23.6 m³, or 23,562 L.

### How do you find the volume of an oval pool?

Multiply length × width × depth by π/4, about 0.785, because an ellipse covers π/4 of the rectangle around it. A 30 × 15 ft oval with 4 ft of water holds 1,413.7 ft³, or 10,575 US gallons. The common shortcut of length × width × depth × 5.9 gives 10,620 gallons, because 5.9 rounds up 0.785 × 7.48 = 5.875.

### How much chlorine raises a pool by 1 ppm?

One ppm needs 1 mg of available chlorine per litre, so 10,000 US gallons (37,854 L) needs 37.9 g: about 10.2 fl oz of 12.5% liquid, 12.8 fl oz of 10% liquid or 2.1 oz of 65% cal-hypo. The CDC advises keeping free chlorine at 1 ppm or more in pools and 3 ppm or more in hot tubs, with pH between 7.0 and 7.8.

### How long does it take to fill a pool with a hose?

Divide the volume by the flow rate. At 30 L/min the default 75,000 L pool takes 2,500 minutes, about 41 h 40 min, and at 9 US gallons a minute a 13,536-gallon round pool takes about 25 hours. To find your own flow rate, time how long the hose takes to fill a bucket of known size and divide the volume by the minutes.

### Quelle est la précision de « Pool volume and tank capacity calculator » ?

La précision dépend de vos données et des hypothèses de la méthode. Le calcul décimal utilise 50 chiffres significatifs, mais les estimations, méthodes numériques et données sources peuvent être moins précises ; l’arrondi affiché ne supprime pas ces limites. Exemples résolus vérifiés à partir de sources indépendantes : 5. Par exemple, « 10 × 5 m pool, 1 m to 2 m deep, +2 ppm with 12.5% liquid » est vérifié à l’aide de Python decimal: 10 × 5 × 1.5 = 75 m³; 75,000 L ÷ 30 L/min = 2,500 min; 2 mg/L × 75,000 L = 150 g ÷ 125 g/L = 1.2 L.

### D’où vient cette méthode ?

Clean Pool Math — chlorine per 10,000 gal per 1 ppm: 13 fl oz of 10% liquid, 2.1 oz of 65% cal-hypo, 2.4 oz of 56% dichlor; PHTA — Sodium hypochlorite (liquid chlorine) fact sheet; CDC — Operating public pools, hot tubs and splash pads (free chlorine and pH levels).

## Sources

- [Clean Pool Math — chlorine per 10,000 gal per 1 ppm: 13 fl oz of 10% liquid, 2.1 oz of 65% cal-hypo, 2.4 oz of 56% dichlor](https://cleanpoolmath.com/pool-chlorine-calculator/)
- [PHTA — Sodium hypochlorite (liquid chlorine) fact sheet](https://www.phta.org/pub/?id=53f7fd64-1866-daac-99fb-101ba70e231d)
- [CDC — Operating public pools, hot tubs and splash pads (free chlorine and pH levels)](https://www.cdc.gov/healthy-swimming/toolkit/operating-public-pools-hot-tubs-and-splash-pads.html)