Volume R

Rectangular Pool Volume Calculator

Calculate rectangular or square pool capacity in gallons, liters, and cubic feet.

Back to Pool Volume Calculator

Pool Diagram
Enter Dimensions
Your Pool Volume
—
US Gallons
— Liters — m³ — UK gal — ft³

Actual water capacity may vary due to steps, benches, slopes, rounded corners, and the normal waterline.

Water Surface Area
—
ft² / — m²
Approx. Water Weight
—

Water weight only, not total structural load.

lb / — kg / — t
View Calculation
Enter dimensions to see the formula.
Estimate Fill Time & Cost
GPM
/ 1k gal
Estimated fill time: — Estimated water cost (USD): —
Calculate Pump Flow
Required average flow: — — —

Use this as a circulation estimate. Pump sizing also depends on plumbing, filters, and total dynamic head.

Choose a Water-Care Estimate Pick a dosing option below to create a quick result card from this pool volume.

How to Use Rectangular Pool Volume Calculator

  1. Choose average depth or shallow-to-deep mode for constant depth pools or variable depth pools.
  2. Enter the rectangular pool length, pool width, and pool depth in feet or metres.
  3. Read pool volume in US gallons, UK gallons, litres, cubic metres (m³), and cubic feet (ft³).

What to Keep in Mind for Rectangular Pool Volume Calculator

Measure the water, not just the shell

Use actual water depth or a representative average depth, not the full wall or shell height.

Account for shape approximations

Curved or irregular shapes remain planning estimates unless the geometry is measured in more detail.

Major built-in features change capacity

Steps, benches, or tanning ledges that materially change pool volume should be accounted for separately.

Measurement Assumptions & Limits

The rectangular pool volume calculator models your pool as a rectangular prism — length × width × average depth — and converts the resulting cubic footage into US gallons using the factor 7.48052. For this formula to produce a close estimate, the real pool footprint should be a true rectangle (or square) with vertical or near-vertical walls.

Enter the interior water-holding dimensions, not the outer shell or coping measurements. Use actual water depth from the surface to the floor rather than the total wall height. If the pool has a sloped bottom, enter the average of the shallow-end and deep-end depths; for a flat bottom, enter the single constant depth. For step-by-step arithmetic and worked examples, see how to calculate pool volume manually.

Built-in entry stairs, attached spas, benches, and tanning ledges displace water that the flat-floor model does not subtract. If those features cover a significant portion of the pool floor, the calculated volume will be an upper-bound estimate. To understand how calculated cubic feet translate across liquid capacity measures, see our guide to pool volume units and conversions.

How We Verify These Calculations

✓ Formula
Shape matched
→
✓ Units
5 outputs checked
→
✓ QA Passed
Math consistent

The rectangular pool volume formula — length × width × average depth × 7.48052 — is matched to the rectangular prism geometric model. Each conversion factor (US gallons, UK gallons, litres, cubic metres, and cubic feet) is cross-checked against NIST-referenced values to ensure unit consistency across all output panels.

Deterministic quality-assurance checks validate that the implemented code returns the expected numeric result for known rectangular-pool inputs, including both average-depth and shallow-to-deep entry modes. Verification confirms internal math consistency, not a guarantee that your specific pool matches a perfect rectangular prism.

Rectangular Pool Volume at a Glance

Three example rectangular pool sizes compared side by side, all at 5 ft average depth.

16 × 32 ft
Pool Volume
19,150
US Gallons
72,491 L 2,560 ft³
18 × 36 ft
Pool Volume
24,237
US Gallons
91,747 L 3,240 ft³
20 × 40 ft
Pool Volume
29,922
US Gallons
113,267 L 4,000 ft³
16 × 32 ft 18 × 36 ft 20 × 40 ft 16×32 — 19,150 gal 18×36 — 24,237 gal 20×40 — 29,922 gal

Top-down view showing relative pool sizes to scale — all at 5 ft average depth

Rectangular Pool Volume Formula

Multiply length, width, and average depth in feet. The factor 7.48 converts cubic feet to US gallons.

Volume (US gallons) = Pool Length x Pool Width x Average Depth x 7.48

The calculator uses 7.48052 US gallons per cubic foot (displayed as 7.48 in formulas). Some quick-reference guides round this factor to 7.5.

How to Calculate Volume of a Rectangular Pool

Use the standard rectangular pool volume formula to determine how many gallons of water your pool holds. This applies to every rectangular and square pool size.

Every rectangle pool volume calculation starts with three measurements: Length, Width, and Average Depth. Multiply them together to get the cubic footage, then convert to gallons using the standard factor.

Volume (gallons) = Length × Width × Avg Depth × 7.48

The multiplier 7.48 converts cubic feet to US gallons. Some quick-reference formulas round the conversion factor to 7.5, while this calculator uses 7.48052 US gallons per cubic foot.

✦ Worked Example — 20×40 Pool

A 20 ft × 40 ft pool with an average depth of 5 ft:

20 × 40 × 5 = 4,000 ft³ → 4,000 × 7.48 =

≈ 29,922 Gallons
Length Width D Depth L × W × D × 7.48 = Gallons

Understanding Rectangle Pool Size Dimensions

Most rectangle pools slope from a shallow end to a deep end. Knowing how to measure and average your pool depth is essential for an accurate pool volume calculation.

Water Surface 3 ft Shallow 7 ft Deep Avg: 5 ft (3 + 7) ÷ 2 = 5 ft average depth

To find the average depth of a rectangular pool with a slope, measure the water depth at the shallow end and the deep end, then use this formula:

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

For a pool with a 3 ft shallow end and a 7 ft deep end, the average depth is (3 + 7) ÷ 2 = 5 ft. This average is used in the volume formula to account for the slope of the pool floor.

If your pool has a more complex floor shape — such as a hopper bottom or multiple depth zones — measure at several points along the length and average all readings for a more accurate result.

Rectangular Pool Size and Volume Chart

Quick reference table for example rectangular pool sizes. All volumes are calculated using a 5 ft average depth.

Swipe horizontally to view all columns

Pool Size (ft) Average Depth US Gallons Litres Cubic Feet (ft³)
9 × 18 5 ft 6,059 22,937 810
12 × 24 5 ft 10,772 40,776 1,440
16 × 32 5 ft 19,150 72,491 2,560
18 × 36 5 ft 24,237 91,747 3,240
20 × 40 5 ft 29,922 113,267 4,000
30 × 15 5 ft 16,831 63,713 2,250
32 × 16 5 ft 19,150 72,491 2,560

* Volumes calculated using the formula: Length × Width × 5 × 7.48. Actual volumes may differ slightly based on pool construction, coping, and water level.

Metric Rectangular Pool Size and Volume Chart

For pools measured in meters, use the metric conversion: 1 cubic meter = 1,000 liters. These are common metric pool sizes.

Swipe horizontally to view all columns

Pool Size Average Depth Litres US Gallons m³
6 × 3 m 1.5 m 27,000 7,133 27.00
8 × 4 m 1.5 m 48,000 12,680 48.00
✦ Metric Formula

For metric pools: Volume (liters) = Length (m) × Width (m) × Depth (m) × 1,000

An 8 × 4 m pool at 1.5 m depth: 8 × 4 × 1.5 = 48 m³ × 1,000 =

= 48,000 Liters (≈ 12,680 Gallons)

* To convert liters to US gallons, divide by 3.785. To convert cubic meters to cubic feet, multiply by 35.315.

Pool Tools

Pool Volume Calculators & Tools

Use the main pool volume result with specialized calculators for water care, pumps, heaters, decks, covers, and pool capacity planning.

Volume Shapes 4 Tools

Pool Volume Calculators

Choose the shape that best matches the pool.

Round Pool Volume Calculator Volume
Estimate water volume for a round pool using diameter and depth.
Oval Pool Volume Calculator Volume
Calculate oval pool water capacity using long diameter, short diameter, and average depth.
L-Shaped Pool Volume Calculator Volume
Calculate total volume for L-shaped pools by splitting the footprint into two rectangular sections.
Kidney Pool Volume Calculator Volume
Estimate water volume for curved kidney-shaped pools using standard shape factor calculations.
Special Types 4 Tools

Special Pool Types

Use these for specific layouts and planning cases.

Above Ground Pool Volume Calculator Volume
Find water capacity for round or oval above-ground pools based on wall height and water level.
Kiddie Pool Volume Calculator Volume
Estimate water capacity and fill volume for small inflatable, plastic, or paddling pools.
Grecian Pool Volume Calculator Volume
Calculate water volume for Grecian-style pools with cut corners and bevelled ends.
Pool Size Estimator & Visualizer Special
Compare common pool dimensions and visually estimate water volume for custom shapes.
Equipment & Sizing 4 Tools

Equipment & Planning Tools

Turn volume and surface area into practical next steps.

Pool Pump Size Calculator Equipment
Estimate recommended pump flow rate, turnover target, and circulation needs for your pool size.
Pool Heater Size Calculator Equipment
Determine BTU heat output requirements and estimated heating time based on pool water volume.
Pool Deck Size Calculator Equipment
Calculate patio, decking, and surround square footage around your pool footprint.
Pool User Capacity Calculator Equipment
Estimate a comfort-planning swimmer count from pool surface area and adjustable spacing.
Water Chemistry 5 Tools

Pool Water Care Calculators

Use your calculated pool volume for dosing estimates.

Pool Chlorine Dosage Calculator Water Care
Estimate chlorine dosage using pool volume and your water test readings.
Pool Shock Dosage Calculator Water Care
Estimate pool shock dosage using pool volume and your water test readings.
Pool Salt Calculator Water Care
Estimate salt requirement using pool volume and your water test readings.
Pool pH Adjustment Calculator Water Care
Estimate ph adjustment using pool volume and your water test readings.
Pool Alkalinity Calculator Water Care
Estimate alkalinity adjustment using pool volume and your water test readings.

Frequently Asked Questions About Rectangular Pool Volume

Common questions about calculating pool water volume.

How many gallons are in a 16 × 32 ft Rectangular Pool?

A 16 × 32 ft Rectangular Pool at 5 ft average depth holds approximately 19,150 US gallons (72,491 litres).

What formula is used for Rectangular Pool volume?

The standard Rectangular Pool formula is Volume (US gallons) = Pool Length x Pool Width x Average Depth x 7.48. Use actual water depth for flat floors and average depth for sloped floors before converting the result.

How do I measure a Rectangular Pool for volume?

Measure the inside water length, inside water width, and actual water depth. If the floor slopes, average the shallow and deep measurements before calculating gallons.

How many litres is a 16 × 32 ft Rectangular Pool?

Multiply US gallons by 3.785 to convert to litres. A 16 × 32 ft Rectangular Pool with about 19,150 gallons is roughly 72,491 litres.

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