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Pool Calculator

Construction

Calculate your rectangular swimming pool's water volume in gallons and cubic feet from length, width, shallow depth, and deep end depth.

6150
680
16
315

Volume (gallons)

21,065.09
Volume (cubic feet)
2,816

This calculator computes your Volume (gallons), Volume (cubic feet) from the values you enter.

Inputs
Length (ft)Width (ft)Shallow End Depth (ft)Deep End Depth (ft)
Outputs
Volume (gallons)Volume (cubic feet)

What is a Pool Volume?

A Pool Calculator computes the water volume of a rectangular swimming pool in gallons and cubic feet, accounting for the sloped bottom typical of residential pools by averaging the shallow-end and deep-end depths. Enter the pool's length, width, shallow depth, and deep depth, and the calculator returns the total water capacity needed for chemical dosing, pump sizing, and fill planning.

This is the standard estimation method used across the pool industry for rectangular in-ground and above-ground pools with a sloped floor transitioning from a shallow swimming area to a deeper end.

How to use this Pool Volume calculator

  1. Measure your pool's length and width in feet along the waterline, at the widest and longest points of the rectangular shape.

  2. Measure the shallow end depth in feet, typically 3 to 4 feet for most residential pools.

  3. Measure the deep end depth in feet, typically 6 to 9 feet depending on the pool's design.

  4. Enter Length (ft) and Width (ft) using the sliders or number fields.

  5. Enter Shallow End Depth (ft) and Deep End Depth (ft) the same way.

  6. Read your Volume (gallons) in the highlighted result card — this is your pool's total estimated water capacity.

  7. Check Volume (cubic feet) if you need the figure for a construction spec or a calculation that uses cubic feet directly.

Formula & Methodology

The calculator uses the standard average-depth rectangular volume formula used throughout the pool industry:

Step 1 — Compute average depth:

> Average Depth (ft) = (Shallow Depth + Deep Depth) ÷ 2

Step 2 — Compute volume in cubic feet:

> Volume (ft³) = Length (ft) × Width (ft) × Average Depth (ft)

Step 3 — Convert to gallons:

> Volume (gal) = Volume (ft³) × 7.4805

Worked example:

- Length = 32 ft, Width = 16 ft, Shallow Depth = 3 ft, Deep Depth = 8 ft
- Average Depth = (3 + 8) ÷ 2 = 5.5 ft
- Volume (ft³) = 32 × 16 × 5.5 = 2,816 ft³
- Volume (gal) = 2,816 × 7.4805 = 21,069.8 gallons

For above-ground round pools or cylindrical storage comparisons, see the Tank Volume Calculator.

Frequently Asked Questions

A typical 32-by-16-foot rectangular in-ground pool with a shallow end of 3 feet and a deep end of 8 feet holds approximately 105,300 gallons. Smaller above-ground pools around 18 by 9 feet with a uniform 4-foot depth typically hold 5,000 to 10,000 gallons depending on exact dimensions.
Most rectangular pools have a sloped bottom transitioning from a shallow end to a deep end, so using either depth alone would overestimate or underestimate total volume. Averaging the two depths approximates the volume of the sloped section reasonably well for typical residential pool geometry, without requiring a more complex sloped-volume calculation.
For pools with a consistent, gradual slope from shallow to deep end, the average-depth method is typically accurate within a few percent of true volume. Pools with a distinct flat shallow shelf followed by a steep drop-off to the deep end may see slightly larger discrepancies, since the transition isn't perfectly linear.
Pool volume determines the correct dosage of chlorine, algaecide, pH adjusters, and other chemicals, all of which are labeled per thousand gallons. It also determines pump and filter sizing for adequate turnover, and is needed to estimate the water cost and time required to fill or refill the pool.
Most residential pool codes and best practices call for turning over the entire pool volume once every 6 to 8 hours during active swimming season. For a 100,000-gallon pool, that means a pump and filter system rated to circulate roughly 12,500 to 16,700 gallons per hour.
Chlorine dosing is typically expressed in ounces or pounds per 10,000 gallons to raise free chlorine by a target ppm — for example, roughly 13 ounces of standard liquid chlorine (12.5%) per 10,000 gallons raises chlorine by about 1 ppm. Always follow the specific product label's dosing instructions using your calculated pool volume.
Yes, for rectangular above-ground pools you can use the same inputs. For round above-ground pools, enter the pool's diameter as both length and width divided appropriately, or use the Tank Volume Calculator, which is built for circular geometry and better suited to round pool shapes.
Pools are typically built with straight, vertical walls and a well-defined shallow-to-deep slope, so a length-times-width-times-average-depth formula works directly without a shape correction factor. Ponds, by contrast, often have curved or sloped banks, which is why the Pond Calculator applies an additional shape factor to avoid overestimating volume.
US residential pools commonly have a shallow end between 3 and 4 feet deep and a deep end between 6 and 9 feet deep, though pools designed primarily for lap swimming or without a diving area may use a more uniform depth throughout, closer to 4 to 5 feet.
Larger pool volumes require proportionally more energy to heat and more water and time to fill, since both cost drivers scale roughly linearly with gallons. Knowing your exact volume lets you estimate heating costs per degree of temperature rise and total fill time based on your water source's flow rate.
Yes — simply enter the same value for both Shallow End Depth and Deep End Depth, and the average depth calculation will simply return that single depth value, giving an accurate volume for a flat-bottom pool.
Since the calculator averages the two depths equally, a one-foot increase in deep end depth has the same effect on total volume as a one-foot increase in shallow end depth. Both depths contribute equally to the average that drives the final volume figure.
Also known as
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