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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 instantly.

Reviewed by the thecalcu.com team · Last updated July 25, 2026

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.

Why Use a Pool Calculator?

Getting pool volume right matters immediately and repeatedly, every chemical dose, every filter turnover calculation, and every water bill for topping off or refilling the pool depends on an accurate gallon figure. Manually working through the average-depth formula and the cubic-feet-to-gallons conversion is straightforward but easy to get slightly wrong, especially when converting between cubic feet and gallons by hand.

This calculator produces an instant, consistent result so you can move directly to sizing chemicals or equipment. If you're deciding between a formal pool and a natural water feature for your backyard, compare results with the Pond Calculator, which uses a similar volume approach adjusted for irregular shapes.

Who Should Use This Calculator?

Pool owners managing their own chemical balancing need accurate gallon figures to correctly dose chlorine, algaecide, pH adjusters, and shock treatments, all of which are labeled per thousand gallons of water.

Pool service technicians and installers use volume calculations daily when quoting equipment, sizing pumps and filters, and setting up new pools for clients.

Homeowners planning a new pool can use this calculator during the design phase to compare how different length, width, and depth combinations affect total water volume, filling time, and ongoing chemical costs.

Property managers and HOA staff overseeing shared community pools need reliable volume figures for compliance with local health code circulation and chemical treatment requirements.

What Insights Does the Pool Calculator Give You?

The calculator returns two outputs: Volume (gallons), the primary highlighted result showing your pool's total water capacity in US gallons, and Volume (cubic feet), the same capacity in cubic feet, useful for construction estimates or equipment specifications that use that unit.

Because the deep end and shallow end are averaged, changing either depth by the same amount produces an identical change in total volume, the calculator treats both ends with equal weight. Length and width, meanwhile, both scale volume linearly and equally, so a pool that's 10% longer and 10% wider than another (at the same depths) will hold roughly 21% more water, not just 20% more.

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.

Show formula & methodology ↓Show less ↑

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

How many gallons does an average backyard pool hold?
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.
Why does the calculator average shallow and deep end depth?
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.
How accurate is the average-depth method for pool volume?
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.
Why do I need to know my pool's exact volume?
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.
What is a good pump turnover rate for a pool of this size?
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.
How much chlorine do I need based on my pool's gallons?
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.
Does this calculator work for above-ground pools?
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.
How is pool volume different from pond volume?
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.
What's a typical shallow-end and deep-end depth for a residential pool?
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.
How does pool size affect heating and filling costs?
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.
Can I use this calculator for a pool with a consistent single depth?
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.
How much does the deep end depth affect total pool volume compared to the shallow end?
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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