Irregular Pool Volume Calculator in Litres and Gallons

How much water your irregular shape pool can hold? Measure and enter your swimming pool’s length and width of different sections into our irregular pool volume calculator for an instant, accurate result.

Irregular Pool Volume Calculator

Irregular Pool Volume Calculator

The longest length of the pool

The widest width of the pool

The average depth of the entire pool

Pool Volume:

gallons

liters

How to Calculate the Volume of an Irregular Shape Pool

An irregular-shaped swimming pool has a custom, freeform shape that doesn’t fit into simple categories like round or rectangle. To estimate its water volume, you need to break the pool into smaller, simple shapes, calculate each one’s volume, and then add them together.

Basic Fundamentals You Need to Know

1. Length and Width of Different Sections

  • Divide your pool into smaller, regular shapes like rectangles, circles, or triangles.
  • Measure the length and width of each.

2. Depth of the Pool

  • Measure at the shallow end and the deep end.
  • If depth varies, find the average.

3. Unit of Measurement

Make sure all measurements are in the same unit (feet, meters, etc.)

4. Conversion Factor

To convert cubic feet to gallons:

  • 1 cubic foot = 7.48 US gallons

Or cubic meters to liters:

  • 1 cubic meter = 1,000 liters

Section Method to Calculate Irregular or Free Form Shape Pool

Step 1: Break the Pool Into Simpler Shapes

Look at your pool’s layout and split it into parts shaped like:

  • Rectangles
  • Circles
  • Triangles
  • Ovals

Example:

  • Section A = Rectangle
  • Section B = Circle
  • Section C = Triangle

Step 2: Measure the Length, Width, and Radius

For each section, measure:

  • Length and width (for rectangles and triangles)
  • Radius (for circles)
  • Depth at shallow and deep ends, then find the average.

Example:

  • Section A (Rectangle): 20 ft × 10 ft
  • Section B (Circle): Radius 5 ft
  • Section C (Triangle): Base 10 ft × Height 6 ft
  • Shallow Depth: 3 ft
  • Deep Depth: 6 ft

Average Depth = (3 + 6) ÷ 2 = 4.5 ft

Step 3: Calculate Volume for Each Section (in Cubic Feet)

Formulas:

  • Rectangle: Length × Width × Average Depth
  • Circle: 3.1416 × Radius² × Average Depth
  • Triangle: (0.5 × Base × Height) × Average Depth

Example:

  • Section A (Rectangle):
    20 × 10 × 4.5 = 900 cubic feet
  • Section B (Circle):
    3.1416 × 5 × 5 × 4.5 = 353.43 cubic feet
  • Section C (Triangle):
    0.5 × 10 × 6 × 4.5 = 135 cubic feet

Step 4: Add All the Volumes Together

900 + 353.43 + 135 = 1,388.43 cubic feet

Step 5: Convert Cubic Feet to Gallons

Use the conversion factor:

  • 1 cubic foot = 7.48 gallons

Now multiply:

  • 1,388.43 × 7.48 = 10,389.7 gallons

Your irregular-shaped pool can hold about 10,390 gallons of water.

Common Irregular Pool Sizes (Estimated Surface Areas)

Surface Area (sq. ft.)Approx. Gallons (5.5 ft avg. depth)
250 sq. ft.10,312 gallons
350 sq. ft.14,437 gallons
450 sq. ft.18,562 gallons
550 sq. ft.22,687 gallons
650 sq. ft.26,812 gallons
750 sq. ft.30,937 gallons
850 sq. ft.35,062 gallons
950 sq. ft.39,187 gallons
1,050 sq. ft.43,312 gallons
1,200 sq. ft.49,500 gallons

Other Pool Metrics