What is Pool Volume Calculator?

Calculate the exact water volume of any swimming pool shape — rectangular, circular, oval, L-shaped, kidney, or Grecian. Enter dimensions and depth (constant or variable from shallow to deep end) to get volume in gallons and liters, plus water weight, estimated fill time, chemical dosing, and the salt dose for a saltwater pool.

Each shape uses a different formula: rectangular pools are length × width × average depth, circular pools are pi × radius² × depth, oval pools combine both axes, L-shaped pools sum two rectangles, kidney pools use the trade-standard 0.45 × length × width × depth approximation, and Grecian pools (a rectangle with cut corners) use a 0.85 × length × width × depth factor. Variable depth averages the shallow and deep ends, which is accurate for pools with a constant slope. Output covers gallons, liters, water weight in pounds and kilograms, fill time at your hose or pump flow rate (defaults to 500 gal/hr), weekly chlorine and shock dosing, and — when you pick the saltwater option — the pounds of salt needed to bring a fresh fill up to the ~3,200 ppm a salt chlorine generator expects. It also reports the water-surface area in square feet and square meters for sizing a cover or solar blanket, an optional fill-cost estimate from your local water rate, and starting amounts of liquid chlorine, pH increaser, alkalinity increaser, and CYA stabilizer for a brand-new fill.

How to use

1. Select your pool shape (rectangular, circular, oval, L-shaped, kidney, or Grecian) and enter dimensions in feet or meters.
2. Set the depth — constant depth or variable with shallow end and deep end values.
3. View the calculated volume in gallons and liters, along with estimated fill time and chemical treatment amounts.

When to use

• Buying chlorine, shock, or algaecide for the first time and needing the exact dose.
• Estimating how long the garden hose will run to fill a new or freshly drained pool.
• Sizing a heater or pump by knowing total water capacity in gallons or liters.

Result

Rectangular pool 30ft × 15ft, shallow end 3ft, deep end 8ft: approximately 18,563 gallons. At typical garden hose flow, that's about 37 hours to fill.

FAQ

How accurate is the average-depth formula for a pool with an irregular floor?

For a single linear slope (shallow to deep), the average is within 2% of true volume. Hopper bottoms or stepped floors under-count by 3-5%. Measure at three or four points along the floor and average those for a more accurate result.

Should I use gallons or liters for chemical dosing?

One US gallon equals 3.785 liters. Use the unit your chemical bottle lists — US dosing guides are in gallons, EU and Australian guides are usually in liters or cubic meters. The calculator shows both so you can match the label exactly.

Can I use this for an above-ground or inflatable pool?

Yes. Pick the matching shape (usually circular or rectangular), enter the dimensions printed on the box or measured with a tape, and use the actual fill depth (water sits a few inches below the wall top). The math is the same as for in-ground pools.

Why does the fill-time estimate look high?

The 500 gal/hr default assumes a standard 5/8-inch garden hose at typical residential pressure. A 3/4-inch hose or stronger municipal supply can hit 700-900 gal/hr. Enter your own flow rate in the hose / pump flow rate field and the fill-time estimate updates instantly.

Does the volume account for steps, ladders, or a deep-end hopper?

No, the formula assumes a clean geometric shape. Built-in steps and benches typically displace less than 3% of total volume, which falls within normal chemical dosing tolerance. For filling, expect to need slightly less water than the estimate shows.

Related Tools