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Calculate kidney pool volume — the total water your pool holds — using the 0.45 shape factor with shallow and deep end depth. Results in gallons and litres.
Kidney Pool
How to Use This Kidney Pool Volume Calculator
This kidney pool volume calculator returns your pool's water volume in US gallons, litres, and cubic feet. Enter 5 measurements and the tool does the rest.
Start by selecting your unit system — Imperial (feet) or Metric (metres) — using the toggle at the top of the calculator. All input labels and results update automatically.
- WIDTH A — WIDER END (A) — the widest measurement across the larger lobe of your kidney pool, perpendicular to the pool's length.
- WIDTH B — NARROWER END (B) — the widest measurement across the smaller lobe, also perpendicular to the pool's length.
- LENGTH (L) — the full end-to-end distance at the pool's longest point.
- SHALLOW END DEPTH (D₁) — the distance from the waterline to the pool floor at the shallowest point.
- DEEP END DEPTH (D₂) — the distance from the waterline to the pool floor at the deepest point. For a flat-bottom kidney pool, enter the same value as D₁.
Results appear instantly in the right-hand panel. The primary display shows gallons (Imperial) or litres (Metric), with secondary lines for the alternate unit and cubic feet or cubic metres. A tilde (~) prefix and "(approx.)" label remind you that the 0.45 factor is an approximation.
Kidney pools vary more than rectangles because the concave indentation depth differs between manufacturers. Measuring both Width A and Width B at the true widest points of each lobe — not at an angle — keeps the 0.45 formula within its published ±5–10% accuracy range.
What Is Kidney Pool Volume?
Kidney pool volume is the total amount of water your kidney-shaped pool holds when filled to the waterline. It is expressed in US gallons, litres, or cubic feet. Knowing this number is the starting point for chemical dosing, pump sizing, heater selection, and accurate water-balance testing.
Because a kidney pool has two rounded lobes joined by a concave indentation, a simple length × width formula over-estimates the water surface area. The industry-standard 0.45 shape factor corrects for this by approximating the kidney pool's surface area as 45% of its bounding rectangle. Without that adjustment, volume calculations can be off by 20% or more — enough to cause real dosing errors.
How to Calculate Kidney-Shaped Pool Volume
To calculate kidney-shaped pool volume you need a shape-specific formula. A kidney pool's concave indentation means a simple length × width calculation over-estimates the water surface area. The 0.45 factor corrects for this by reducing the bounding rectangle area to roughly 45% — far more accurate than treating the pool as an oval or freeform pool volume calculator shape. See our full list of pool volume formulas for other pool shapes.
The Kidney Pool Volume Formula
Volume (ft³) = 0.45 × (A + B) × L × Average Depth
Average Depth = (Shallow End + Deep End) ÷ 2
A = Width A, the wider lobe. B = Width B, the narrower lobe. L = Length, end to end. The multiplier 0.45 is an empirical shape factor — it approximates the kidney pool's water surface area as 45% of the rectangle formed by Width A × Length. All dimensions must be in the same unit (all feet or all metres) before multiplying.
To convert cubic feet to US gallons, multiply by 7.48052. To convert to litres, multiply by 28.3168. Some online calculators round the gallon factor to 7.5 — that introduces a 0.26% over-estimate. This calculator uses the precise 7.48052 factor for accuracy throughout.
Step-by-Step Worked Example
Pool: 16 × 32 ft kidney pool, Width B = 12 ft, Shallow End = 3.5 ft, Deep End = 6.5 ft.
- Average Depth= (3.5 + 6.5) ÷ 2= 5.0 ft
- Sum of widths= 16 + 12= 28 ft
- Est. Surface Area= 0.45 × 28 × 32= 403.2 sq ft
- Volume= 403.2 × 5.0= 2,016 cu ft
- US Gallons= 2,016 × 7.48052= 15,081 gal
- Litres= 2,016 × 28.3168= 57,087 L
How to Measure a Kidney-Shaped Pool
Measuring Width A, Width B, and Length
Width A is the straight-line distance across the widest point of the larger rounded lobe, measured perpendicular to the pool's length. Width B is the same measurement taken across the smaller lobe — also perpendicular. Length runs from one end of the kidney pool to the other at the longest point.
The most common kidney pool measurement mistake is pulling the tape diagonally across a lobe instead of straight across at 90° to the length. A diagonal overestimates the width by 5–12%, which inflates the calculated volume. Always keep the tape perpendicular to the pool's centreline.
Calculating Average Depth
Average Depth = (Shallow End + Deep End) ÷ 2. For example: (3.5 + 6.5) ÷ 2 = 5.0 ft. Measure depth from the waterline straight down to the pool floor — not along a sloped wall.
Most kidney pools have a gradual slope from the shallow end to the deep end. The average of the two endpoint depths approximates the water column's midpoint along that slope. For kidney pools with a flat-bottom shelf and a sudden drop-off, the simple average may under-estimate the shallow section — measure at 3 points across the pool length and average all 3 for a tighter result.
Kidney Pool Volume by Size — Reference Table
The table below shows the volume of a kidney shaped pool at 9 standard sizes. All rows use shallow end depth 3.5 ft + deep end depth 6.5 ft = 5.0 ft average depth. Width B values are typical manufacturer ratios; your exact kidney pool Width B may differ.
Kidney-Shaped Pool Volume Table
| Pool Size (A × L) | Width B | Avg Depth | US Gallons | Litres |
|---|---|---|---|---|
| 12 × 24 ft | 8 ft | 5.0 ft | 8,079 | 30,582 |
| 14 × 28 ft | 9 ft | 5.0 ft | 10,839 | 41,031 |
| 15 × 30 ft | 10 ft | 5.0 ft | 12,623 | 47,785 |
| 16 × 30 ft | 10 ft | 5.0 ft | 13,128 | 49,696 |
| 16 × 32 ft | 12 ft | 5.0 ft | 15,081 | 57,087 |
| 16 × 34 ft | 10 ft | 5.0 ft | 14,879 | 56,322 |
| 18 × 36 ft | 12 ft | 5.0 ft | 18,178 | 68,810 |
| 20 × 38 ft | 14 ft | 5.0 ft | 21,746 | 82,317 |
| 20 × 40 ft | 14 ft | 5.0 ft | 22,890 | 86,649 |
Formula: 0.45 × (A + B) × L × Avg Depth. Gallons = cu ft × 7.48052. Litres = cu ft × 28.3168. The 16×32 kidney pool volume row uses Width B = 12 ft; the 16×34 row uses Width B = 10 ft, which explains the lower volume despite a longer pool. Contact your pool manufacturer for your exact Width B measurement.
Common Pool Volume Comparison
The tables below compare kidney pool volumes against round, oval, rectangular, and Grecian pool shapes at common sizes. All values are independently calculated — not copied — using shape-specific formulas and the 7.48052 gallon conversion factor.
Above-Ground Pools — 48″ Wall (4 ft depth)
| Pool Size | Shape | US Gallons | Litres |
|---|---|---|---|
| 15 ft | دائري | 5,288 | 20,016 |
| 18 ft | دائري | 7,614 | 28,823 |
| 20 ft | دائري | 9,400 | 35,584 |
| 24 ft | دائري | 13,536 | 51,241 |
| 27 ft | دائري | 17,132 | 64,852 |
| 28 ft | دائري | 18,425 | 69,745 |
| 11 × 25 ft | Oval | 6,463 | 24,464 |
| 15 × 25 ft | Oval | 8,813 | 33,360 |
| 15 × 30 ft | Oval | 10,575 | 40,032 |
| 18 × 33 ft | Oval | 13,959 | 52,842 |
| 18 × 38 ft | Oval | 16,075 | 60,849 |
Above-Ground Pools — 52″ Wall (4.33 ft depth)
| Pool Size | Shape | US Gallons | Litres |
|---|---|---|---|
| 15 ft | دائري | 5,728 | 21,684 |
| 18 ft | دائري | 8,249 | 31,225 |
| 20 ft | دائري | 10,184 | 38,549 |
| 24 ft | دائري | 14,664 | 55,511 |
| 27 ft | دائري | 18,560 | 70,256 |
| 28 ft | دائري | 19,960 | 75,557 |
| 11 × 25 ft | Oval | 7,001 | 26,503 |
| 15 × 25 ft | Oval | 9,547 | 36,140 |
| 15 × 30 ft | Oval | 11,457 | 43,368 |
| 18 × 33 ft | Oval | 15,123 | 57,246 |
| 18 × 38 ft | Oval | 17,414 | 65,919 |
Inground Pools — 5 ft Average Depth
| Pool Size | Shape | US Gallons | Litres |
|---|---|---|---|
| 12 × 24 ft | مستطيل | 10,772 | 40,776 |
| 16 × 32 ft | مستطيل | 19,150 | 72,491 |
| 16 × 36 ft | مستطيل | 21,544 | 81,552 |
| 18 × 36 ft | مستطيل | 24,237 | 91,746 |
| 20 × 40 ft | مستطيل | 29,922 | 113,267 |
| 16 × 32 ft | Oval | 15,040 | 56,934 |
| 18 × 36 ft | Oval | 19,036 | 72,057 |
| 20 × 40 ft | Oval | 23,501 | 88,960 |
| 17 × 33 ft | Grecian | 17,835 | 67,514 |
| 17 × 37 ft | Grecian | 19,997 | 75,698 |
| 20 × 36 ft | Grecian | 22,890 | 86,649 |
| 20 × 44 ft | Grecian | 27,977 | 105,905 |
| 16 × 30 ft (B=10) | Kidney | 13,128 | 49,696 |
| 16 × 34 ft (B=10) | Kidney | 14,879 | 56,322 |
| 20 × 38 ft (B=14) | Kidney | 21,746 | 82,317 |
Round: π × r² × depth. Oval: π × (W/2) × (L/2) × depth. Rectangle: L × W × depth. Grecian: L × W × 0.85 × depth. Kidney: 0.45 × (A+B) × L × depth. All conversions use 7.48052 gal/cu ft and 28.3168 L/cu ft.
Notice that the 16×32 kidney pool (15,081 gal) holds about 21% less water than the 16×32 rectangle (19,150 gal) at the same depth. This gap matters for chemical dosing — over-treating by 4,000 gallons wastes product and can damage pool surfaces. For a full breakdown by pool shape and size, see pool volume by size.
Kidney Pool Volume in Litres
This kidney pool volume calculator litres conversion uses the precise factor 1 cu ft = 28.3168 litres. All results display litres alongside gallons automatically.
For the 16×32 ft kidney pool worked example above: 2,016 cu ft × 28.3168 = 57,087 litres. You can also convert from gallons directly: 15,081 gal × 3.78541 = 57,087 L. In Metric mode, this calculator works natively in metres and returns litres as the primary unit (m³ × 1,000).
If you need litres for an Australian, UK, or European context, switch the unit toggle to Metric and enter your kidney pool dimensions in metres. The calculator multiplies m³ by 1,000 for litres and by 264.172 for US gallons. For a full guide to litre-based pool calculations, see pool volume in litres.
How Many Chemicals Does a Kidney Pool Need?
Every chemical dose — chlorine, pH adjuster, algaecide, stabiliser — is calculated per gallon or per litre of pool water. An inaccurate kidney pool volume leads directly to under-dosing or over-dosing.
A 16×32 kidney pool holds 15,081 gallons, not the 19,150 gallons that the same bounding dimensions would hold for a rectangle. Dosing based on 19,150 gallons would add 27% more chlorine than needed — risking bleached liners and skin irritation. Always use the kidney-specific 0.45 formula or this calculator before adding any chemical.
For dosage tables and step-by-step instructions, see our pool chemical dosing guide. Return to the pool volume calculator homepage for other pool shapes.
Frequently Asked Questions
What is the formula for kidney pool volume?
Volume (ft³) = 0.45 × (Width A + Width B) × Length × Average Depth. Average Depth equals (Shallow End + Deep End) ÷ 2. The 0.45 is an empirical kidney shape factor that accounts for the concave indentation reducing the kidney pool's water surface area to roughly 45% of its bounding rectangle. Multiply cubic feet by 7.48052 for US gallons or by 28.3168 for litres. A 16×32 kidney pool at 5 ft average depth yields 2,016 cu ft = 15,081 gallons (57,087 litres).
What does kidney pool volume mean?
Kidney pool volume means the total water a kidney-shaped pool holds when filled to the waterline. It is measured in US gallons, litres, or cubic feet. Because a kidney pool's concave indentation reduces its water surface area compared to a rectangle, volume is calculated with the 0.45 shape factor: 0.45 × (Width A + Width B) × Length × Average Depth. A 16×32 ft kidney pool at 5 ft average depth holds about 15,081 gallons (57,087 litres).
How do I measure a kidney-shaped pool?
Measure 3 distances at the waterline. Width A crosses the widest point of the larger lobe, perpendicular to the kidney pool's length. Width B crosses the widest point of the smaller lobe, also perpendicular. Length runs end to end at the longest point. Then measure from the waterline straight down to the floor at the shallowest and deepest spots. A common kidney pool mistake is measuring at a diagonal — this inflates width by 5–12% and over-estimates volume.
How many gallons does a 16×32 kidney pool hold?
About 15,081 US gallons (57,087 litres) at 5 ft average depth with Width B = 12 ft. The 16x32 kidney shaped pool volume calculation is: 0.45 × (16 + 12) × 32 × 5 = 2,016 cu ft, then 2,016 × 7.48052 = 15,081 gallons. This kidney pool volume calculator gallons result uses the precise 7.48052 factor — not the rounded 7.5 some competitors use. At a shallower 4 ft average depth, the same kidney pool holds 12,065 gallons (45,669 litres).
How many gallons does a 16×34 kidney pool hold?
About 14,879 US gallons (56,322 litres) at 5 ft average depth with Width B = 10 ft. The calculation: 0.45 × (16 + 10) × 34 × 5 = 1,989 cu ft × 7.48052 = 14,879 gallons. Despite the longer 34 ft length, this kidney pool holds slightly less water than a 16×32 (15,081 gal) because its Width B is narrower at 10 ft vs 12 ft. Your exact kidney pool volume depends on the Width B of your specific mold.
Can I use this for an above-ground kidney pool?
Yes. Enter Width A, Width B, and Length as normal. For the depth fields, enter your wall height as both the Shallow End Depth and Deep End Depth since above-ground kidney pools have a flat bottom. A 12 × 20 ft above-ground kidney pool (Width B = 8 ft) with a 48-inch (4 ft) wall holds approximately 5,386 gallons (20,388 litres) using the 0.45 kidney formula.
How many litres does a kidney-shaped pool hold?
A mid-size 16×32 ft kidney pool at 5 ft average depth holds 57,087 litres (15,081 US gallons). Multiply cubic feet by 28.3168 to convert any kidney pool volume to litres. For the 16×32 example: 2,016 cu ft × 28.3168 = 57,087 L. Larger kidney pools like the 20×40 ft (Width B = 14 ft) hold 86,649 litres (22,890 US gallons) at the same 5 ft average depth.
How accurate is the 0.45 kidney pool formula?
The 0.45 kidney pool formula is an industry-standard approximation accurate to within ±5–10% of a full 3D laser survey. The 0.45 factor assumes the kidney pool's concave indentation reduces the water surface area to 45% of the bounding rectangle (Width A × Length). Deeper indentations drop the real factor below 0.45, producing less volume. For tighter accuracy, measure your kidney pool's actual surface area and enter it in the "I know my pool's surface area" section of this calculator.
What is the volume of a kidney shaped pool vs a rectangular pool of the same size?
A kidney-shaped pool holds about 21% less water than a rectangular pool with the same bounding dimensions. At 5 ft average depth, a 16×32 ft kidney pool (Width B = 12 ft) holds 15,081 gallons (57,087 litres), while a 16×32 ft rectangular pool holds 19,150 gallons (72,491 litres). That 4,069-gallon gap matters for chemical dosing — using the rectangular volume for a kidney pool over-doses every treatment by roughly 27%.