Round & Oval Pool Volume Calculator
Estimate water volume, average depth, fill weight, and filling cost for circular or oval pools with flat or sloped bottoms.
Pool inputs
Live results
Calculation breakdown
| Measure | U.S. customary | Metric |
|---|---|---|
| Surface area | 452.39 ft² | 42.03 m² |
| Average depth | 4.25 ft | 1.30 m |
| Pool volume | 1,922.65 ft³ | 54.45 m³ |
| Water capacity | 14,386 gal | 54,455 L |
| Estimated water weight | 120,025 lb | 54,443 kg |
How to use this pool volume calculator
What this calculator does
This calculator estimates the water held by a round or oval pool by treating the filled portion as a circular or elliptical cylinder. It supports a flat bottom or a simple linear slope represented by shallow- and deep-end measurements. The result is useful for planning a first fill, checking a utility estimate, sizing chemical treatments, and comparing pool dimensions. It is not a structural design tool and does not model steps, benches, curved transitions, wall taper, displaced equipment, or an irregular floor.
When to use it
Use it before filling a new above-ground pool, when estimating the refill volume after draining, when converting a measured pool into gallons or liters for maintenance calculations, or when comparing the likely water cost of two pool sizes. For safe operation and water-quality practices after filling, consult the CDC's home pool water treatment and testing guidance.
How to calculate
- The calculator opens with a complete 24-foot round-pool example and an immediately available Excel workbook. Choose Measurement system, Pool shape, and Depth profile first.
- Replace the demonstration dimensions with measurements taken at the normal waterline. For an oval pool, enter both full axes. For a sloped pool, enter both end depths.
- Review Pool volume first, then use the secondary results and the calculation table to check area, depth, weight, and unit conversions.
- Enter your local Water rate to estimate the fill charge, then select Download Excel for a current-state workbook. Reset clears the demonstration values and may disable export until a complete valid set is entered again.
Input guide
Measurement system controls data entry units. U.S. customary accepts feet and a rate in dollars per 1,000 U.S. gallons; Metric accepts meters and a rate in dollars per cubic meter. Switching systems converts existing valid values rather than relabeling them. Pool shape is required: Round uses one full diameter, while Oval adds Pool width, the shorter full axis. Depth profile is required: Constant depth uses one Water depth; Shallow & deep ends uses two positive depths and averages them. This average-depth method assumes a reasonably uniform slope.
Pool length / diameter, Pool width, Water depth, Shallow-end depth, and Deep-end depth accept ordinary positive decimals, such as 24, 12.5, or 3.75. Do not enter unit letters, fractions such as 3 1/2, scientific notation, or decimal commas. For the varied-depth mode, the deep end must be at least as deep as the shallow end. Water rate accepts zero or a positive decimal; 6.50 means $6.50 per 1,000 gallons in U.S. customary mode. A rate of zero keeps the geometry valid and displays a $0.00 cost.
Output guide
Pool volume is the central capacity estimate, displayed in gallons with liters underneath in U.S. customary mode, or cubic meters with gallons underneath in Metric mode. Average depth is either the entered constant depth or the arithmetic mean of the two end depths. Surface area is the horizontal water-surface footprint. Water weight uses standard approximate water density and is helpful for scale awareness, not structural certification. Estimated fill cost multiplies capacity by the entered utility rate; it excludes sewer charges, fixed fees, taxes, evaporation, and top-offs. The breakdown table reports the same canonical geometry in both unit systems.
Worked example
The startup example is a round pool with a 24 ft diameter, 3.5 ft shallow end, 5 ft deep end, and a water rate of $6.50 per 1,000 gallons. Average depth is (3.5 + 5) ÷ 2 = 4.25 ft. Surface area is π × (24 ÷ 2)² = 452.39 ft². Multiplying area by average depth gives 1,922.65 ft³. Using the exact U.S. gallon conversion produces about 14,386 gallons, and 14.386 × $6.50 gives an estimated fill cost of $93.51. NIST provides authoritative background on volume conversion factors.
Formula and assumptions
Round: V = π × (diameter ÷ 2)² × average depth
Oval: V = π × (length ÷ 2) × (width ÷ 2) × average depth
A constant-depth pool uses the entered depth directly. A varied-depth pool uses (shallow depth + deep depth) ÷ 2. This is exact for a floor whose depth changes linearly across the pool and is a practical approximation for many simple slopes. The standard cylinder relationship is also summarized by Wolfram MathWorld's cylinder reference, while an oval pool follows the corresponding elliptic-cylinder geometry.
Measurement and planning tips
Measure to the intended waterline rather than to the top of the wall. Take the diameter through the center, not along a chord, and measure both oval axes at their widest points. An error in diameter has a squared effect on round-pool volume, so a small measuring mistake can shift the answer noticeably. Actual billed water may differ because hoses, filters, plumbing, backwashing, splash-out, and meter rounding are outside the geometric model. EPA water-efficiency guidance notes that pool covers can help reduce evaporation; see its pool water-efficiency guidance for conservation context.