Swimming Pool Volume Calculator
Calculate your pool's water volume based on its shape and dimensions. Get results in gallons, liters, and cubic feet, plus estimated chemical amounts.
Pool Volume Formulas
Rectangular
Round
Oval
Why Pool Volume Matters
Knowing your pool's exact water volume is the foundation of proper pool maintenance. Every chemical you add, from chlorine to pH balancer to algaecide, requires dosing based on how many gallons your pool holds. Getting the volume wrong means either under-treating (leading to algae, bacteria, and cloudy water) or over-treating (wasting chemicals and potentially irritating skin and eyes).
Pool volume also matters when sizing pumps, filters, and heaters. A pump that is too small for your pool cannot circulate water properly, while an oversized heater wastes energy.
Accurate Dosing
Get chemical amounts right so your water stays clean and safe
Equipment Sizing
Choose the right pump, filter, and heater for your pool
Save Money
Stop wasting chemicals by guessing your pool size
Common Pool Sizes and Volumes
If you are not sure what to expect, this reference table shows typical volumes for common residential pool sizes. Your actual volume will depend on your specific depths.
| Pool Size | Shape | Approx. Volume (Gallons) |
|---|---|---|
| 12 ft diameter, 4 ft deep | Round | ~3,400 gallons |
| 15 x 30 ft, 3.5-5.5 ft deep | Rectangular | ~15,200 gallons |
| 16 x 32 ft, 4-8 ft deep | Rectangular | ~23,000 gallons |
| 18 x 36 ft, 3.5-8 ft deep | Kidney / Oval | ~24,000 - 27,000 gallons |
| 20 x 40 ft, 4-9 ft deep | Rectangular | ~38,800 gallons |
Chemical Dosing Guide
These are general starting points for a typical residential pool. Always test your water before adding chemicals and follow the product label instructions.
Chlorine (Sodium Hypochlorite)
Maintain 1-3 ppm free chlorine. For every 10,000 gallons, add about 6 oz of liquid chlorine (12.5% concentration) to raise the level by 1 ppm. Shock treatment uses 1 lb of calcium hypochlorite per 10,000 gallons.
pH Balancer
Keep pH between 7.2 and 7.6. To raise pH, add 6 oz of soda ash per 10,000 gallons to raise it by 0.2. To lower pH, use 12 oz of muriatic acid per 10,000 gallons to drop it by 0.2.
Alkalinity
Maintain total alkalinity between 80-120 ppm. Add 1.5 lbs of sodium bicarbonate (baking soda) per 10,000 gallons to raise alkalinity by 10 ppm.
Stabilizer (Cyanuric Acid)
Keep CYA between 30-50 ppm for outdoor pools. Add 13 oz per 10,000 gallons to raise CYA by 10 ppm. Stabilizer protects chlorine from breaking down in sunlight.
Maintenance Tips by Season
Spring Opening
Remove the cover, clean debris, and fill the pool to the proper level. Run the pump for 24 hours, then test and balance all chemical levels. Shock the pool before swimming.
Summer Maintenance
Test water 2-3 times per week during heavy use. Run the pump 8-12 hours daily. Brush walls and vacuum weekly. Keep an eye on water level since evaporation speeds up in hot weather.
Fall Preparation
Skim leaves frequently to prevent staining. Reduce pump run time as temperatures drop. Begin winterization steps when temps consistently stay below 65 degrees Fahrenheit.
Winter Closing
Lower the water level below the skimmer, blow out plumbing lines, add winterizing chemicals, and install a tight-fitting cover. An air pillow under the cover protects against ice expansion.
Frequently Asked Questions
How do I measure my pool if it has an irregular shape?
Break the pool into simpler shapes. For example, a kidney pool can be roughly estimated as an oval with about 85% of the full oval volume. Measure the longest length, widest width, and average depth, then apply the oval formula and multiply by 0.85. For L-shaped pools, calculate each rectangular section separately and add them together.
What is the 7.48 multiplier in the formulas?
There are 7.48 gallons in one cubic foot of water. After calculating volume in cubic feet (length times width times depth), multiplying by 7.48 converts the result to US gallons.
How accurate does my pool volume need to be?
For chemical dosing, being within 10-15% is usually fine. Most chemical instructions give ranges, and you should always test your water after adding chemicals and adjust. For equipment sizing, closer estimates matter more since an undersized pump cannot be fixed with a dosing adjustment.
How do I find my average depth?
Measure the depth at the shallowest point and the deepest point. Add them together and divide by two. If your pool has a flat bottom, just measure at any point. For pools with a deep end drop-off, measure at 3-4 points and average them.
How many gallons does my above-ground pool hold?
Most above-ground pools are round with a consistent depth. Use the round formula: volume = 3.14159 times radius squared times depth times 7.48. For example, a 24-foot round pool that is 4 feet deep holds about 13,594 gallons.
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