Kidney Pool Calculator

The Kidney-Shaped Pool is a mid-century modern classic. Its organic curves fit naturally into backyard landscapes, offering distinct zones for shallow play and deep-end diving. However, its lack of straight lines makes it a nightmare to measure. You can’t just multiply Length x Width.

The Kidney Pool Calculator uses the industry-standard geometric approximation to turn your curves into numbers. Whether you are calculating water volume for chemical shock, sizing a solar cover, or estimating resurfacing costs, this tool gives you the answers.

How to Use This Calculator

You need three specific measurements to describe a kidney shape:

1. The Measurements

• Width A (Large Bulge): The widest point across the deep end (or larger end).
• Width B (Small Bulge): The widest point across the shallow end (or smaller end).
• Length (L): The longest distance from the outer edge of End A to the outer edge of End B.
• Average Depth: Shallow Depth + Deep Depth.

2. The Logic

The calculator uses the formula: . This constant (0.45) accounts for the “pinch” in the middle of the kidney shape.

Calculations for Maintenance

Chemical Dosing

Adding chlorine or algaecide requires knowing your pool’s volume in Gallons or Liters. Under-dosing leads to algae blooms; over-dosing causes skin irritation.

• Formula:

Pump Sizing

Pool pumps are rated by “Turnover Rate”—how long it takes to filter the entire volume of water. To choose the right horsepower, you must know if you are moving 15,000 gallons or 30,000 gallons.

Heating

Sizing a gas heater or heat pump depends strictly on surface area (evaporation loss) and total volume (thermal mass).

Calculations for Renovation

Solar Covers & Safety Nets

Covers are sold as rectangles. You buy a rectangle big enough to cover the entire Length x Largest Width, then trim it to fit the curves. This calculator helps you define that minimum bounding box.

Resurfacing (Plaster/Pebble)

If you are hiring a contractor to re-plaster the pool, they charge by the “Internal Surface Area” (Floor + Walls).

• Internal Area Est:

Frequently Asked Questions (FAQ)

How do I find the Perimeter of a kidney pool?

Mathematically, it is very complex. The easiest way is physical: lay a long rope or garden hose around the water’s edge, mark it, and then measure the length of the rope.

Is the 0.45 factor accurate?

It is accurate to within +- 5% for standard kidney shapes. If your pool is a custom “Freeform” shape with wild curves, this approximation may be off. In that case, use the “Cubic” method (divide pool into slices) for better precision.

What if my pool has a “Cove”?

A cove (radius at the bottom where wall meets floor) slightly reduces volume, but for general chemical dosing, you can ignore it. For liner ordering, you must measure it exactly.

Final Words

Don’t let the curves throw you a curveball. The Kidney Pool Calculator straightens out the math, keeping your water crystal clear and your maintenance on track.