Pond Calculator — Volume, Pump Size & Fish Stocking
Enter your pond dimensions to instantly find total water volume in US gallons and litres, the pump flow rate needed to keep water healthy, and the maximum fish load your pond can support.
Pond shape
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Total water volume your pond holds
- 1
Volume (ft³)
10 × 8 × 2 = 160 - 2
Volume (US gallons)
160 × 7,48052 = 1.1971 ft³ = 7.48052 US gallons.
Hvordan fungerer denne lommeregner?
Pond volume (US gal) = Length × Width × Depth (ft) × 7.48 for rectangular; π × r² × Depth × 7.48 for circular. Size your pump to turn the volume over once per hour. Stock no more than 1 inch of fish per 10 gallons until biological filtration is well established.
Formel
How this is calculated
Pond volume is the foundation of every sizing decision. The calculator multiplies the cross-sectional area by the average water depth to get cubic feet, then converts using 7.481 US gallons per cubic foot. For circular ponds use the diameter; for oval (elliptical) ponds the formula uses π × (half-length) × (half-width) × depth — the same as the area of an ellipse. For irregular shapes, measure the average length, average width and average depth and accept a ±10–15% margin.
Pump sizing follows the common rule of turning over the full pond volume at least once per hour for ornamental fish; heavily stocked koi ponds should aim for 1.5–2× per hour. The calculator shows both the minimum and a 1.5× recommended flow rate. Biological and mechanical filtration capacity should match or exceed the pump flow.
Fish stocking uses the widely cited beginner guideline of 1 inch of fish body length per 10 US gallons of water. This is conservative and safe for startup; mature, heavily planted, well-filtered ponds can support more. Season, temperature, species and filtration all affect the true carrying capacity.
Ofte stillede spørgsmål
Take depth readings at several points across the pond (centre, halfway out in multiple directions, near the edges) and average them. For bowl-shaped ponds a common rule is 0.4 × maximum depth gives a reasonable average.
For ornamental fish (goldfish, small koi) aim for 1× turnover per hour — the full pond volume in GPH. For a dedicated koi pond with high stocking density, target 1.5–2× per hour. Always add 20–30% to account for head pressure losses in plumbing and filter media.
It is a conservative starter guideline suitable for new ponds without mature biological filtration. An established pond with good filtration, aeration and regular water changes can safely support considerably more. Body width and species waste load matter — a fat 12-inch koi has far more bioload than a 12-inch slender goldfish.
Også kendt som
TG we-Calculate Editorial Team. (2026). Pond Calculator — Volume, Pump Size & Fish Stocking [Online calculator]. TG we-Calculate. https://we-calculate.com/da/calculator/pond-calculator
TG we-Calculate Editorial Team. "Pond Calculator — Volume, Pump Size & Fish Stocking." TG we-Calculate. 2026. https://we-calculate.com/da/calculator/pond-calculator.
TG we-Calculate Editorial Team, "Pond Calculator — Volume, Pump Size & Fish Stocking," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/da/calculator/pond-calculator
@misc{wecalculate_pond_calculator, title = {Pond Calculator — Volume, Pump Size & Fish Stocking}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/da/calculator/pond-calculator}}, year = {2026}, note = {TG we-Calculate} }
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