# Swimming Pool Calculator

Calculate swimming pool volume in gallons for rectangular, oval, and circular pools. Get chemical estimates for chlorine shock and pH adjustment plus fill.

## What this calculates

Knowing your pool's exact volume in gallons is the foundation for every chemical treatment, pump sizing, and heater selection decision. This calculator handles rectangular, oval, and circular pool shapes with variable depths and provides practical chemical dosage estimates.

## Inputs

- **Pool Shape** — options: Rectangular, Oval, Circular — Select the shape of your pool
- **Length** (ft) — min 0 — Pool length (or diameter for circular pools)
- **Width** (ft) — min 0 — Pool width (not used for circular pools)
- **Shallow End Depth** (ft) — min 0 — Water depth at the shallow end
- **Deep End Depth** (ft) — min 0 — Water depth at the deep end

## Outputs

- **Pool Volume** (gallons) — Total water volume in US gallons
- **Chlorine (Shock)** (lbs) — Granular chlorine for 10 PPM shock treatment
- **pH Up (Soda Ash)** (oz) — Soda ash to raise pH by 0.2 (per treatment)
- **Fill Time** (hours) — Estimated fill time with a garden hose (~9 GPM)

## Details

Pool volume is calculated using the average depth method: Average Depth = (Shallow End + Deep End) / 2. For rectangular pools, the volume is Length x Width x Average Depth x 7.48 gallons/ft³. Oval pools multiply by 0.7854 (π/4) to account for the curved shape, and circular pools use the standard cylinder formula.

Chemical dosages are based on standard pool chemistry guidelines. Chlorine shock treatment uses 65% calcium hypochlorite at a target of 10 PPM, roughly double the normal maintenance level of 3-5 PPM. The pH adjustment estimate uses soda ash (sodium carbonate) to raise pH by 0.2 units per application, which is the recommended incremental approach.

The fill time estimate assumes a standard garden hose flowing at 9 GPM. Actual flow rates vary based on water pressure, hose diameter, and distance from the source. A typical residential pool takes 1-3 days to fill with a single garden hose. Contact your water utility before filling, as some charge overage fees or require notification for large-volume fills.

## Frequently Asked Questions

**Q: How do I calculate the volume of a pool with a diving well?**

A: For pools with a distinct diving well, calculate the shallow section and deep section separately using the rectangular calculator, then add the volumes together. Use each section's actual dimensions and depths for the most accurate result.

**Q: How many gallons are in a standard residential pool?**

A: A typical 12x24-foot residential pool with 3.5 to 5.5 foot depth holds about 12,000-15,000 gallons. A larger 16x32-foot pool with 3 to 8 foot depth holds about 19,000-23,000 gallons. Olympic pools (164x82 feet) hold approximately 660,000 gallons.

**Q: How much chlorine do I need for weekly maintenance?**

A: For routine maintenance (not shock), you need about 2-4 PPM of free chlorine. That's roughly 1/4 to 1/2 the shock treatment amount shown in the calculator. Add chlorine in the evening to reduce UV degradation, and test daily during heavy use or hot weather.

**Q: How much does it cost to fill a pool with water?**

A: Water costs vary by location, but the national average is about $4-$10 per 1,000 gallons. A 15,000-gallon pool costs roughly $60-$150 to fill. Some municipalities offer a sewer credit since pool water doesn't enter the sewer system. Contact your utility to ask.

**Q: How often should I shock my pool?**

A: Shock your pool every 1-2 weeks during swim season, after heavy use or rain, and whenever chlorine levels drop below 1 PPM. Spring opening and fall closing also require shock treatment. Always shock at dusk and wait 8-12 hours before swimming.

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Source: https://vastcalc.com/calculators/construction/swimming-pool
Category: Construction
Last updated: 2026-04-21