March 27, 20264 min read

Pool Volume Calculator — Calculate Gallons & Liters for Any Pool Shape

Calculate swimming pool volume in gallons and liters for rectangular, round, and irregular pools. Essential for chemical dosing, heating, and water cost estimation.

pool volume calculator swimming pool calculator pool gallons water volume calchub

Knowing your pool's exact volume matters for everything — chlorine dosing, heating costs, water bills, pump sizing, and filling time estimates. Getting it wrong means over- or under-treating your water, which is either wasteful or unsafe.

The CalcHub Pool Volume Calculator computes volume for rectangular, round, oval, and irregular pools.

Pool Volume Formulas

Rectangular Pool

Volume = Length × Width × Average Depth

Average depth = (Shallow end + Deep end) / 2

Length (ft)	Width (ft)	Shallow	Deep	Avg Depth	Volume (gal)	Volume (L)
20	10	3 ft	6 ft	4.5 ft	6,727	25,457
30	15	3 ft	8 ft	5.5 ft	18,506	70,037
40	20	3 ft	9 ft	6 ft	35,904	135,897

Gallons = L × W × Avg D × 7.481 (cubic feet to gallons) Liters = L × W × Avg D × 28.317 (cubic feet to liters)

Round/Circular Pool

Volume = π × Radius² × Average Depth

Diameter (ft)	Depth (ft)	Volume (gal)	Volume (L)
12	4	3,392	12,837
15	4	5,300	20,059
18	4	7,634	28,893
24	4	13,572	51,368

Oval Pool

Volume = Length × Width × Avg Depth × 0.7854

The 0.7854 factor accounts for the oval shape (π/4).

Chemical Dosing by Pool Volume

Chemical	Dose per 10,000 gallons	Purpose
Chlorine (liquid, 12%)	10 fl oz	Sanitization
Shock treatment	1 lb	Super-chlorination
pH Up (soda ash)	6 oz	Raise pH by 0.2
pH Down (muriatic acid)	10 fl oz	Lower pH by 0.2
Algaecide	4–8 oz	Algae prevention
Stabilizer (CYA)	13 oz	UV protection for chlorine

Getting volume wrong by 30% means your chlorine dose is off by 30% — either under-treating (unsafe) or over-treating (skin/eye irritation and wasted chemicals).

Heating Cost Estimate

To heat a pool by 1°F:

BTU needed = Volume (gallons) × 8.33 (lbs/gallon) × 1°F

Pool Volume	Heat 10°F Rise	Gas Cost (₹70/therm)	Electric Cost (₹8/kWh)
10,000 gal	833,000 BTU	~₹580	~₹1,950
20,000 gal	1,666,000 BTU	~₹1,170	~₹3,900
30,000 gal	2,499,000 BTU	~₹1,750	~₹5,850

Solar pool covers can reduce heating costs by 50–70% by preventing evaporation heat loss.

Fill Time Estimate

Pool Volume	Garden Hose (~10 GPM)	1" Line (~25 GPM)	Tanker Truck (~6,000 gal)
5,000 gal	8.3 hours	3.3 hours	1 truck
15,000 gal	25 hours	10 hours	2.5 trucks
30,000 gal	50 hours	20 hours	5 trucks

How to Use the Calculator

Open the CalcHub Pool Volume Calculator
Select pool shape (rectangle, circle, oval, irregular)
Enter dimensions (length, width/diameter, depths)
See: volume in gallons, liters, and cubic feet

How do I calculate an irregularly shaped pool?

Divide the pool into sections (rectangles + semicircles), calculate each section's volume separately, and add them. For kidney-shaped pools, multiply length × width × average depth × 0.45 for a reasonable estimate.

How much water does my pool lose to evaporation?

A typical pool loses 0.25–0.5 inches of water per day through evaporation in summer. For a 400 sq ft pool, that's 60–125 gallons per day. A pool cover reduces this by 90%+.

Should I drain and refill my pool or treat the existing water?

Usually treat. Draining and refilling a 20,000-gallon pool costs ₹5,000–15,000 in water alone, plus chemical rebalancing takes days. Only drain for major repairs or when total dissolved solids (TDS) exceed 2,000 ppm.

Volume Calculator — any 3D shape
Water Usage Calculator — household water consumption
BTU Calculator — heating capacity
Area Calculator — pool surface area