Stock Tank Pool Calculator
Calculate how many gallons your galvanized stock tank pool holds from its diameter and depth, for pump and fill-cost sizing.
How this calculator works
A stock tank pool is a cylinder: this calculator converts your tank’s diameter (in inches) to a radius in feet, then uses the classic cylinder-volume formula with your fill depth to get cubic feet, and converts to gallons at 7.48 gallons per cubic foot.
Formula: Radius (ft) = Diameter (in) ÷ 24. Cubic feet = π × Radius² × Height (ft). Gallons = Cubic feet × 7.48.
Worked example
An 8 ft (96 in) diameter tank filled 2 ft deep:
- Radius: 96 ÷ 24 = 4 ft
- Cubic feet: π × 4² × 2 ≈ 100.5310 ft³
- Gallons: 100.5310 × 7.48 ≈ 751.97 gallons
- At $0.01/gallon for fill water, that’s $7.52.
Coverage reference
| Tank size | Gallons |
|---|---|
| 48 in dia x 1 ft | 94.00 gallons |
| 96 in dia x 2 ft | 751.97 gallons |
| 192 in dia x 4 ft | 6,015.77 gallons |
How to measure your stock tank
Measure the tank’s inside diameter in inches and decide your intended fill depth in feet — usually a few inches below the rim, not the tank’s full height, to leave room for splash and bather displacement. Use the resulting gallon figure to size a small above-ground pump and filter, aiming for a full turnover roughly every 4-8 hours given how quickly a small volume can cloud up with regular use.
Frequently asked questions
How many gallons does a stock tank pool hold?
It depends on the tank's diameter and how deep you fill it — an 8-foot (96-inch) diameter galvanized stock tank filled 2 feet deep holds about 752 gallons. Enter your tank's height and diameter and this calculator returns the exact figure for your setup.
Why are stock tank pools ('plunge pools') so popular?
Galvanized livestock stock tanks became a DIY plunge-pool trend because they're cheap relative to a built-in pool, need no excavation, and can be set up above-ground in an afternoon. An 8-foot tank is the most common size — big enough to cool off in but small enough to fit on a patio or small yard.
What size pump and filter do I need for a stock tank pool?
Most 8-foot stock tank pools (700-800 gallons) work with a small above-ground pool pump/filter combo rated for 1,000-1,500 gallons, sized to turn over the full volume in roughly 4-8 hours. Undersized pumps struggle to keep the water clear given how much bather load a small volume gets relative to its size.
Do I fill a stock tank pool to the very top?
No — most stock tank pools are filled a few inches below the rim to leave freeboard for splash-out and bather displacement, so your 'depth' entry should reflect your intended water line, not the tank's total height. A typical 2-foot fill in a taller tank leaves headroom above the waterline.
Does the diameter measurement mean inside or outside the tank wall?
Use the inside diameter for the most accurate gallon count, since that's the actual water-holding dimension — the outside diameter (often what's advertised, e.g. '8-foot tank') includes the wall thickness and will slightly overstate true volume, though the difference is usually small enough to ignore for pump sizing.
Estimates only. Verify quantities with your supplier before purchasing.