Enter the inside dimensions and fill depth—not the outside dimensions. The calculator subtracts an optional occupant-displacement estimate.
How the calculation works
Rectangular volume uses length × width × fill depth. Round tubs use the cylinder formula; oval tubs use an elliptical footprint. US cubic inches are converted at 231 cubic inches per gallon, and metric cubic centimeters at 1,000 per liter.
Use the result
- Size chemical doses only from the product label and compatible test results.
- Check pump, filter, and chiller requirements against actual operating conditions.
- Leave freeboard so entry does not overflow the tub.
- See the water-maintenance guide and maintenance planner.
Calculator note: Results are planning estimates, not medical advice or equipment guarantees. Verify assumptions against the manufacturer’s documentation and local electricity or water conditions.
