Volume O

Round Pool Volume Calculator

Estimate water volume for a round pool using diameter and depth.

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 Round Pool Volume Calculator

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

What to Keep in Mind for Round 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 round pool volume calculator uses the cylinder formula — π × radius² × depth — where the radius is half the entered diameter. The result in cubic feet is then converted to US gallons, UK gallons, litres, cubic metres, and cubic feet automatically. For full formula derivations and calculations, explore how to calculate pool volume manually.

Measure the full diameter by stretching a tape across the widest point of the pool through the exact center. For above-ground round pools, measure the interior water-holding diameter, not the outer frame or the top rail. Use actual water depth from the surface to the floor, since the wall typically extends several inches above the waterline. Review our explanation of understanding pool-volume units for converting between cubic feet, gallons, and litres.

The cylinder model assumes a perfectly circular footprint and vertical walls. Slight manufacturing irregularities, soft-sided flex, or tapered walls will cause the real volume to differ from the geometric calculation. Average depth works well for flat-bottom pools; for sloped or bowl-shaped bottoms, it introduces an approximation.

How We Verify These Calculations

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

The round pool formula — π × (diameter ÷ 2)² × depth — follows the standard cylinder volume model. Output conversions to US gallons, UK gallons, litres, cubic metres, and cubic feet are each verified against NIST conversion factors to prevent cascading unit errors.

Deterministic QA confirms that the calculator returns correct results for representative round-pool inputs. Verification means the math and conversions are internally consistent with the cylinder model — it does not eliminate real-world variance from wall flex, non-circular footprints, or unmeasured features.

Round Pool Volume at a Glance

Example round pool sizes compared side by side.

12 ft diameter
4 ft Depth
3,384
US Gallons
12,810 L 452 ft³
24 ft diameter
5 ft Depth
16,921
US Gallons
64,051 L 2,262 ft³
30 ft diameter
5 ft Depth
26,438
US Gallons
100,080 L 3,534 ft³
12 ft 24 ft 30 ft 12ft 24ft 30ft to scale

Top-down view showing relative round pool sizes to scale — concentric circle comparison

Round Pool Volume Formula

Uses the area of a round pool multiplied by average depth. The radius is half the diameter.

Volume (US gallons) = π x Radius² x Average Depth x 7.48

The radius is half of the pool diameter. A 24-foot round pool has a 12-foot radius.

How to Calculate Volume of a Round Pool

The round pool volume formula uses the pool's diameter (or radius) and average depth to determine total water capacity in gallons, liters, or cubic feet.

A round pool volume calculation requires two measurements: the Diameter (the distance across the pool) and the Average Depth. The formula uses π (pi ≈ 3.14159) to calculate the circular area, then multiplies by depth and the gallon conversion factor.

Volume (gallons) = π × Radius² × Avg Depth × 7.48

The Radius is half the diameter. So for a 24 ft diameter pool, the radius is 12 ft. The multiplier 7.48 converts cubic feet to US gallons.

✦ Worked Example — 24 ft Round Pool

A 24 ft diameter pool with an average depth of 5 ft:

π × 12² × 5 = π × 144 × 5 = 2,261.9 ft³ → 2,261.9 × 7.48 =

≈ 16,921 Gallons
Diameter Radius R = D ÷ 2 π × R² × D × 7.48 = Gallons

Understanding Round Pool Depth

Most above-ground round pools have a uniform depth, while in-ground round pools may slope. Here's how to measure correctly for an accurate volume calculation.

Water Surface Diameter Depth Wall Wall Measure water depth, not wall height

For above-ground round pools with a flat bottom, measure the actual water depth — not the wall height. Water typically sits 4–6 inches below the top of the wall.

For in-ground round pools with a bowl-shaped or sloped floor, measure the depth at the center (deepest point) and at the edge (shallowest point), then average them:

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

For a flat-bottom above-ground pool that is 4 ft deep, simply use 4 ft as your depth. No averaging is needed since the floor is level.

Round Pool Size and Volume Chart

Quick reference table for the most common round pool diameters. Above-ground pools (8–18 ft) use 4 ft depth; in-ground pools (24–30 ft) use 5 ft average depth.

Swipe horizontally to view all columns

Diameter Depth Volume (Gallons) Volume (Liters) Volume (ft³)
8 ft 4 ft 1,504 5,693 201
10 ft 4 ft 2,350 8,896 314
12 ft 4 ft 3,384 12,810 452
15 ft 4 ft 5,288 20,016 707
18 ft 4 ft 7,614 28,823 1,018
24 ft 5 ft 16,921 64,051 2,262
30 ft 5 ft 26,438 100,080 3,534

* Volumes calculated using π × Radius² × Depth × 7.48. Above-ground pools (8–18 ft) assume 4 ft water depth. Larger in-ground pools (24–30 ft) assume 5 ft average depth.

Metric Round Pool Size and Volume Chart

For round pools measured in meters, the formula uses cubic meters converted to liters (1 m³ = 1,000 liters).

Swipe horizontally to view all columns

Diameter Depth Volume (Liters) Volume (Gallons) Volume (m³)
3 m 1.2 m 8,482 2,241 8.48
3 m 1.5 m 10,603 2,801 10.60
4 m 1.2 m 15,080 3,984 15.08
5 m 1.5 m 29,452 7,781 29.45
✦ Metric Round Pool Formula

For metric round pools: Volume (liters) = π × Radius² (m) × Depth (m) × 1,000

A 3 m diameter pool at 1.5 m depth: π × 1.5² × 1.5 × 1,000 = π × 3.375 × 1,000 =

≈ 10,603 Liters (≈ 2,801 Gallons)

* To convert liters to US gallons, divide by 3.785. To convert meters to feet, multiply by 3.281.

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.

Rectangular Pool Volume Calculator Volume
Calculate rectangular or square pool capacity in gallons, liters, and cubic feet.
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 Round Pool Volume

Common questions about calculating pool water volume.

How many gallons are in a 12 ft diameter Round Pool?

A 12 ft diameter Round Pool at 4 ft average depth holds approximately 3,384 US gallons (12,810 litres).

What formula is used for Round Pool volume?

The standard Round Pool formula is Volume (US gallons) = π x Radius² 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 Round Pool for volume?

Measure the inside diameter straight across the center, then use half of that value as the radius. Always use actual water depth, not wall height.

How many litres is a 12 ft diameter Round Pool?

Multiply US gallons by 3.785 to convert to litres. A 12 ft diameter Round Pool with about 3,384 gallons is roughly 12,810 litres.

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