Understanding pool shape and average depth
Shape determines the area formula; the shallow/deep average-depth approach is standard for sloped pools but is only exact for a uniform-slope floor.
| Shape | Area formula | Notes |
|---|---|---|
| Rectangular | Length × Width | Most common in-ground residential pool shape |
| Round | π × (Length ÷ 2)² | Length entered is treated as the pool's diameter |
| Oval | (π ÷ 4) × Length × Width | Standard pool-industry approximation for an oval footprint |
- Averaging shallow and deep-end depth assumes a fairly uniform, gradual slope between the two — pools with a distinct flat shallow shelf followed by a steep drop-off (rather than a constant grade) will have an actual volume somewhat different from this simple average-depth estimate.
- This calculator does not account for stairs, benches, swim-outs, spillover spas or other volume-displacing features common in custom pool designs, which reduce actual water volume below a pure shape-and-depth estimate.
- For a pool of uniform (constant) depth throughout, enter the same value for both shallow-end and deep-end depth, which makes the average-depth step a no-op.
What does a pool volume calculator compute?
A pool volume calculator estimates the total water volume of a swimming pool by combining its surface area (based on shape and dimensions) with its average depth, since most in-ground pools slope from a shallower end to a deeper end rather than having a single uniform depth throughout. Averaging the shallow and deep-end depths is a standard, widely used approximation that works well for pools with a fairly consistent, gradual slope.
Three shapes are supported: rectangular (length × width), round (using length as the diameter), and oval (using the standard pool-industry oval area approximation of π/4 × length × width). Each shape's area is multiplied by the average depth to get total volume.
How to use this pool volume calculator
- Select the pool shape: rectangular, round (enter length as the diameter) or oval.
- Enter the pool's length and width in meters (for a round pool, width is not needed since length is used as the diameter).
- Enter the shallow-end depth and deep-end depth in meters — for a pool with uniform (constant) depth, enter the same value for both.
- Read the total volume in liters, US gallons and cubic meters, along with the average depth used in the calculation.
The formula behind pool volume
Average depth equals the shallow-end depth plus the deep-end depth, divided by two. Surface area depends on shape: rectangular area = length × width; round area = π × (length ÷ 2)² (using length as the diameter); oval area = (π ÷ 4) × length × width, a standard pool-industry approximation. Volume equals area multiplied by average depth, then converted to liters (× 1,000) and US gallons (× 264.172).
Worked example (calculator defaults): a rectangular pool 10 m long, 5 m wide, with a 1.2 m shallow end and 1.8 m deep end. Average depth = (1.2 + 1.8) ÷ 2 = 1.5 m. Area = 10 × 5 = 50 m². Volume = 50 × 1.5 = 75 m³. In liters: 75 × 1,000 = 75,000 L. In US gallons: 75 × 264.172 ≈ 19,813 gal.
Common mistakes
- Entering only one depth value (assuming uniform depth) for a pool that actually slopes from shallow to deep, which skews the volume estimate.
- Using length as the diameter for a round pool but still entering a separate width value, which is unnecessary and unused for that shape.
- Forgetting that stairs, benches, swim-outs and other built-in features reduce actual water volume below a simple shape × average-depth estimate.
- Mixing up length and width for rectangular or oval pools, which doesn't change rectangular results (since they multiply the same way) but can matter for record-keeping and other calculations that depend on orientation.
Часто задаваемые вопросы
How many liters are in a 10 m × 5 m pool with a 1.2–1.8 m depth?
A 10 m by 5 m rectangular pool with a 1.2 m shallow end and 1.8 m deep end (average depth 1.5 m) holds about 75,000 liters (75 m³), which is roughly 19,813 US gallons.
How do I calculate pool volume with different shallow and deep depths?
Average the shallow-end and deep-end depths together, then multiply that average depth by the pool's surface area to estimate total volume — this is a standard approximation that works well for pools with a fairly uniform slope from shallow to deep.
How is oval pool volume calculated?
Oval pool surface area uses the standard pool-industry approximation of (π ÷ 4) × length × width, which is then multiplied by the average depth to get the total volume, the same way as rectangular and round pools.
Does this calculator account for pool stairs or a swim-out ledge?
No — it estimates volume from the overall shape and average depth only. Stairs, benches, swim-outs, spillover spas and similar built-in features displace some water volume and are not subtracted from this estimate.
How many gallons are in a cubic meter of pool water?
One cubic meter of water equals exactly 1,000 liters, which converts to approximately 264.172 US gallons — this is the standard metric-to-US-customary volume conversion used throughout this calculator.
Источники
- Standard geometric area formulas for rectangular, circular and oval shapes, combined with the average-depth approximation widely used in the pool industry for sloped-floor pools.
- Association of Pool & Spa Professionals (APSP/PHTA) — general residential pool sizing and volume-estimating conventions.
- Standard unit conversions: 1 m³ = 1,000 L = 264.172 US gallons.