A pond volume calculator estimates how much water your garden or koi pond holds. Enter the average length, width, and depth for results in gallons and liters.
Pond volume is the approximate amount of water a pond holds, used for pump sizing, liner calculations, fish stocking rates, and water treatment dosing.
Most ponds have irregular shapes, so volume is estimated using average dimensions rather than precise formulas. The general approach: measure the longest length, widest width, and average depth, then apply a shape correction factor.
Rectangular pond: V = Length × Width × Average Depth.
Circular/Oval pond: V = Length × Width × Avg Depth × 0.785.
Irregular pond: V = Length × Width × Avg Depth × 0.45 to 0.65 (depending on shape).
Example: Oval pond 3m × 2m × 0.6m avg: V = 3 × 2 × 0.6 × 0.785 = 2.826 m³ = 2,826 L = 747 gal.
2 × 1.5 × 0.5 m (oval): V = 2×1.5×0.5×0.785 = 1.178 m³ = 1,178 L = 311 gal.
4 × 3 × 1.2 m (oval): V = 4×3×1.2×0.785 = 11.304 m³ = 11,304 L = 2,986 gal.
5 × 3 × 0.8 m, factor 0.55: V = 5×3×0.8×0.55 = 6.6 m³ = 6,600 L.
20 × 10 × 2 m (oval): V = 20×10×2×0.785 = 314 m³ = 314,000 L = 82,963 gal.
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Answers to common questions about the pond volume calculator.
Liner length = pond length + (2 × depth) + 2 ft overlap. Liner width = pond width + (2 × depth) + 2 ft overlap. Always add extra for anchoring.
General rule: 1 koi per 250 gallons (946 L) for healthy stocking. Koi grow large (2-3 feet) and produce heavy bioload. A 2,000 gallon pond supports ~8 koi.
The pump should circulate the full pond volume at least once every 1-2 hours. A 2,000 gallon pond needs a pump rated at 1,000-2,000 GPH (gallons per hour).
Take depth measurements at 6-10 points across the pond. Add them all up and divide by the number of measurements. Include the deepest and shallowest areas.
Water weighs 8.34 lbs/US gallon (1 kg/liter). A 1,000 gallon pond holds 8,340 lbs (3,785 kg) of water.