Handy tools
Water tank & pond calculator
How much water have you got, and how long will it last? Measure your tank, stock tank or pond and the water depth to see gallons when full, gallons now and the days left at your daily use - in feet and gallons, or meters and liters.
How we work it out
- Round tank: π × radius² × depth. Stock tank or trough: length × width × depth.
- Pond or dugout: the floor is the top size less the side slope on both sides; the volume uses the prismoidal formula (top, middle and floor areas).
- Days left: water in it now ÷ the water you use a day. 1 ft³ = 7.48 US gal; 1 acre-foot = 325,851 gal (one acre, one foot deep); 1 US gal = 3.785 L.
An estimate for a level, regular shape. Real ponds are rarely perfectly square and lose water to evaporation and seepage, and tanks lose some volume below the outlet - so keep a margin, and check your tank maker’s rated capacity. Take care near deep water and never climb into a tank to measure. Nothing you type is stored or sent anywhere. Need other units? Try the farm unit converter.
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