Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Estimated pool gallons
12,049
Average width
14.00
ft
Estimated cubic feet
1,607
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter length (ft).
- 2Enter width at widest point 1 (ft).
- 3Enter width at widest point 2 (ft).
- 4Enter average depth (ft).
- 5Read your estimated pool gallons on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Kidney-shaped pools are a popular in-ground design prized for their curved, organic footprint, but that same curve makes exact volume math harder than a simple rectangle or circle. The standard industry approximation treats a kidney pool as two overlapping circles' worth of area using its two width measurements (taken at the widest points of each lobe) averaged together with the pool's overall length, then multiplied by depth and a shape correction factor of roughly 0.45 in place of a full rectangle's implied area. This calculator takes the two width measurements, overall length, and average depth (from shallow to deep end) to return an estimated gallon count that pool professionals commonly use for chemical dosing on kidney and free-form pools where a perfectly precise formula isn't practical. Because kidney pools are irregular, this is always an estimate — for exact volume, a pool service can calculate from as-built architectural drawings — but it's accurate enough for day-to-day chemical balancing.
Worked example
Using the values the calculator loads with:
Inputs
- Length: 30 ft
- Width at widest point 1: 16 ft
- Width at widest point 2: 12 ft
- Average depth: 4.5 ft
Results
- Estimated pool gallons: 12,049
- Average width: 14
- Estimated cubic feet: 1,607
What each field means
Inputs
- Length (ft)
- The length used in the calculation, measured in ft. Starts at 30 ft so you have a working example on load. Accepted range: 5–60 ft.
- Width at widest point 1 (ft)
- The width at widest point 1 used in the calculation, measured in ft. Starts at 16 ft so you have a working example on load. Accepted range: 3–40 ft.
- Width at widest point 2 (ft)
- The width at widest point 2 used in the calculation, measured in ft. Starts at 12 ft so you have a working example on load. Accepted range: 3–40 ft.
- Average depth (ft)
- The average depth used in the calculation, measured in ft. Starts at 4.5 ft so you have a working example on load. Accepted range: 1–12 ft.
Results
- Estimated pool gallons
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Average width
- ft
- Estimated cubic feet
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why is there a 0.85 correction factor?
Kidney and free-form pools have curved edges that hold less water than a full rectangle of the same overall length and width, so pool professionals apply a shape correction factor, commonly 0.85, to approximate the actual curved area more accurately.
How accurate is this estimate compared to a rectangular pool calculation?
It's an approximation rather than an exact figure — typically within 10-15% of true volume — which is accurate enough for chemical dosing but not for precise engineering or water-loss leak calculations.
Where do I measure the two widths on a kidney pool?
Measure straight across at the widest point of each of the pool's two curved lobes, which is usually near each rounded end of the kidney shape rather than at the narrow waist in the middle.
Can I get an exact volume for my custom pool?
Yes, your pool builder's as-built drawings or a pool service company can calculate exact volume from the actual excavation plans, which is worth requesting if you need precise numbers for equipment sizing rather than chemical dosing.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Oval Pool Gallons Calculator
Convert an oval above-ground pool's length, width, and depth into total gallons.
Round Pool Gallons Calculator
Get total gallons for a round or circular above-ground pool from diameter and depth.
Pool Shock Calculator
Calculate how many bags of pool shock to use based on pool gallons and shock level needed.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Kidney Pool Gallons Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/pool-gallons-kidney-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/pool-gallons-kidney-calculator" target="_blank" rel="noopener">Kidney Pool Gallons Calculator — RevenueLab</a> (2026).</p>
Source: [Kidney Pool Gallons Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/pool-gallons-kidney-calculator) (2026).