Pool Volume Calculator

Pool Volume Calculator

Select your pool shape, enter your dimensions, and get the exact volume in gallons, liters, cubic feet, and cubic meters. Supports rectangular, round, oval, kidney-shaped, L-shaped, and freeform pools. Includes water weight, fill time, and pump sizing.

Interactive Pool Volume Calculator

Adjust sliders or type directly to see updates

Pool Shape
ft
1 ft40.5 ft80 ft
ft
1 ft20.5 ft40 ft
ft
1 ft5.5 ft10 ft
ft
1 ft8.5 ft16 ft

Pool Volume Results

Calculated
Total Volume
21,065gal
79,740liters
2816 ft³·79.74 m³

Total water volume in your pool.

Water Weight
175,683lbs
79,689kg
87.8 tons

Weight of water at 1 gallon = 8.34 lbs.

Practical Info
Garden Hose Fill Time
35.1hours
at 10 GPM flow rate
Recommended Pump Rate
43.9GPM
for 8-hour turnover
Quick Reference

Common pool sizes and their volume in gallons

Pool SizeAvg DepthGallonsLiters
12 ft Round3.5 ft2,96011,210
15 ft Round4 ft5,29020,030
18 ft Round4.5 ft8,57032,440
24 ft Round4.5 ft15,23057,660
27 ft Round4.5 ft19,27072,970
12 × 24 ft Rect4.5 ft9,70036,720
14 × 28 ft Rect5 ft14,66055,500
16 × 32 ft Rect5.5 ft21,07079,770
18 × 36 ft Rect5.5 ft26,660100,940
20 × 40 ft Rect6 ft35,910135,920
Pool Volume Formulas

How to calculate pool volume by shape

Rectangular & Square Pools

Length × Width × Avg Depth × 7.48 = Gallons
Average Depth = (Shallow End + Deep End) ÷ 2. The 7.48 constant converts cubic feet to US gallons.

Round & Circular Pools

π × Radius² × Avg Depth × 7.48 = Gallons
Quick formula: Diameter × Diameter × Avg Depth × 5.9 = Gallons. Works for above-ground and inground round pools.

Oval Pools

π × (L/2) × (W/2) × Avg Depth × 7.48 = Gallons
Simplified: Length × Width × Avg Depth × 5.9 = Gallons.

Kidney-Shaped Pools

(Width A + Width B) × Length × 0.45 × Avg Depth × 7.48 = Gallons
Width A and Width B are the two widest points of the kidney bulges. The 0.45 accounts for the curved indentation.

L-Shaped & Lazy-L Pools

Section 1 Volume + Section 2 Volume = Total Gallons
Divide the L into two rectangles, calculate each separately, then add them together.

Freeform & Irregular Pools

Longest Length × Widest Width × Avg Depth × 5.9 = Gallons
The 5.9 multiplier approximates the irregular shape. For more precision, divide the pool into smaller geometric sections.

Why It Matters

Why knowing your pool's exact volume is critical

Chemical Dosing

Chlorine, shock, pH adjusters, algaecide, and stabilizer doses are all calculated per gallon. Wrong volume = wrong dose.

Pump & Filter Sizing

Your pump must turn over 100% of pool water every 8 hours. Undersized pump = poor circulation and algae growth.

Heater Sizing

Pool heaters are rated by BTU output relative to pool volume. An undersized heater won't heat your pool effectively.

Fill Time & Water Cost

Know how long it takes to fill your pool and estimate water costs. A 20,000-gallon pool takes ~33 hours with a garden hose.

How to measure pool depth accurately

  • Measure water depth, not wall height. Use a pole or tape measure from the pool floor to the water surface line.
  • Take multiple depth readings. Measure at the shallow end, the deep end, and any transition points. Average them for best accuracy.
  • For above-ground pools, measure inside dimensions. The inner diameter and water depth are what matter, not the outer frame size.
  • Account for steps and benches. Large built-in steps or tanning ledges reduce volume. Subtract their approximate volume from the total.
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Pool volume calculator — common questions.

Specific questions about calculating pool volume, measurement tips, and how to use these numbers for pool care.

For rectangular pools with a constant depth: Volume (Gallons) = Length (ft) × Width (ft) × Average Depth (ft) × 7.48. The 7.48 is the exact number of US gallons in one cubic foot of water. Many pool professionals round this to 7.5 for quick estimates.
Use the formula: π × Radius² × Average Depth × 7.48 = Gallons. Or with diameter: Diameter × Diameter × Average Depth × 5.9 = Gallons. For example, a 24-foot round pool with 4.5 feet of water: 24 × 24 × 4.5 × 5.9 = approximately 15,293 gallons.
For oval pools: π × (Length/2) × (Width/2) × Average Depth × 7.48 = Gallons. A simplified version: Length × Width × Average Depth × 5.9 = Gallons. This works because an oval is essentially a circle stretched along one axis.
For kidney pools: (Width A + Width B) × Total Length × 0.45 × Average Depth × 7.48 = Gallons. Width A and Width B are the two widest points of the kidney bulges. The 0.45 multiplier accounts for the curved indentation.
Divide the L-shape into two separate rectangles. Calculate each rectangle individually: Length × Width × Average Depth × 7.48 = Gallons. Then add both volumes together. Our calculator has separate input fields for each section of the L.
For freeform pools, approximate using: Longest Length × Widest Width × Average Depth × 5.9 = Gallons. The 5.9 multiplier (instead of 7.48) accounts for the irregular shape having less area than a full rectangle. For greater precision, divide the pool into smaller geometric sections and sum them.
Always measure the actual water depth — from the pool floor to the water surface line (usually at the midpoint of the skimmer opening). Measuring the top edge of the pool wall will overestimate your volume by 10-20%, causing you to add excess chemicals.
For metric dimensions in meters: Length (m) × Width (m) × Average Depth (m) = Volume in Cubic Meters (m³). Since 1 m³ = 1,000 Liters, multiply cubic meters by 1,000 to get liters. To convert US Gallons to Liters, multiply gallons by 3.785.
A 16×32 foot rectangular pool with an average depth of 5.5 feet (3-foot shallow end, 8-foot deep end) contains approximately 21,000 gallons (16 × 32 × 5.5 × 7.48 = 21,068 gallons). With a constant 4-foot depth, it's about 15,360 gallons.
A 24-foot round above-ground pool with 4.5 feet of water contains approximately 15,300 gallons (24 × 24 × 4.5 × 5.9 = 15,293 gallons). At 4 feet deep, it's about 13,594 gallons.
One US gallon of fresh water weighs 8.34 lbs (3.785 kg). A 20,000-gallon pool contains approximately 166,800 lbs — over 83 tons of water. Our calculator shows the water weight automatically.
A typical garden hose delivers 9-12 gallons per minute (GPM). At 10 GPM, that's 600 gallons per hour. A 15,000-gallon pool takes about 25 hours of continuous running. Our calculator estimates fill time at 10 GPM.
Pool standards recommend turning over 100% of your water every 8 hours. Required Flow Rate (GPM) = Total Gallons ÷ 480. For example, a 24,000-gallon pool needs a pump rated for at least 50 GPM (24,000 ÷ 480 = 50).
Standard liquid chlorine (10-12.5% sodium hypochlorite): add approximately 10-12 fluid oz per 10,000 gallons to raise Free Chlorine by 1.0 ppm. Granular Cal-Hypo 65%: add 1 lb per 10,000 gallons to raise chlorine by about 5-7 ppm.
Yes. Hot tubs and spas are typically rectangular or round. Use the same calculator — just enter the smaller dimensions. A typical 7×7 foot hot tub with 3 feet of water is about 1,100 gallons.