Free Online Tool

Pool Gallon Calculator

Find out exactly how many gallons are in your pool — plus how much chlorine and shock you need.

✓ Round, rectangular & oval ✓ Gallons & liters ✓ Chemical guide included
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Pool Gallon Calculator

Enter your pool dimensions below

Select pool shape:

Rectangular Standard in-ground
Round / Circle Above-ground pools
🥚 Oval Oval above-ground
ft
Longest side of pool
ft
Shortest side of pool
ft
Shallow + deep end ÷ 2
%
How full is the pool?

Your Results

Gallons
Liters
Chlorine oz (weekly)
Shock oz (opening)

💡 Tip will appear here.

📊 Quick Reference — Common Pool Sizes
Pool SizeApprox. GallonsChlorine (oz/week)
12 ft round, 4 ft deep~2,700 gal~3 oz
18 ft round, 4 ft deep~6,100 gal~6 oz
24 ft round, 5 ft deep~13,500 gal~14 oz
16×32 ft, 5 ft avg depth~19,200 gal~19 oz

How to Calculate Pool Gallons

The formula depends on pool shape. For rectangular pools: Gallons = Length × Width × Average Depth × 7.48. For round pools: Gallons = Diameter × Diameter × Average Depth × 5.9. The multiplier (7.48 or 5.9) converts cubic feet to gallons.

Why it matters: Knowing your pool volume is essential for adding the correct amount of chemicals. Adding too much chlorine can irritate eyes and skin. Too little, and algae and bacteria grow rapidly.

Pool Chemical Guide

Pro tip: Always test your pool water with a test strip or kit before adding chemicals. Never add chemicals to a pool with bathers — wait at least 30 minutes after dosing.