Pond Volume Calculator
Calculate pond volume in gallons and liters for oval, rectangular, and irregular ponds.
Includes pump size and fish stocking capacity estimate.
Garden pond volume must be calculated accurately to size the pump correctly, determine filtration capacity, calculate chemical treatments, and maintain healthy water conditions for fish and aquatic plants.
Core formulas by pond shape:
Rectangular: Volume (gallons) = Length (ft) × Width (ft) × Depth (ft) × 7.48
Oval: Volume (gallons) = Length (ft) × Width (ft) × Depth (ft) × 5.87 (π/4 × 7.48 ≈ 5.87)
Circular: Volume (gallons) = π × radius² (ft) × Depth (ft) × 7.48
Metric version: Volume (liters) = Length (m) × Width (m) × Depth (m) × 1,000
Pump sizing rule: Your pump should circulate the entire pond volume once per hour (once every 2 hours for ponds without fish). Pump Flow Rate (GPH) = Total Pond Volume (gallons)
Worked example: Oval pond: 8 ft long × 5 ft wide × 2 ft average depth Volume = 8 × 5 × 2 × 5.87 = 469.6 gallons ≈ 470 gallons Recommended pump: at least 470 GPH flow rate For koi pond (extra filtration): 940 GPH (2× turnover)
Pond volume reference table:
| Pond Size | Approximate Volume |
|---|---|
| Small garden pond (6×4×1.5 ft) | ~270 gallons |
| Medium pond (10×6×2 ft) | ~898 gallons |
| Large koi pond (15×10×3 ft) | ~3,366 gallons |
Chemical treatment dosing: Once you know the volume, you can precisely dose algaecides, beneficial bacteria, water conditioners, and fish medications — preventing over- or under-dosing, which can harm aquatic life. Always measure volume before adding any treatments.