Recheck volume, test reading, product strength, density or purity, and the selected target.
Volume calculator
Hot-tub volume
Compare shell geometry with measured hose-flow fill volume.
Your measurements
Enter known values
Values stay in this browser. No chemistry details are sent anywhere.
Calculated planning amount
687 US gal
2,602 L · calculated confidence
Before actingMeasure first. Follow the product label. Add chemicals separately; circulate and retest.
- Formula
- length × width × average depth
- Assumptions
- 25% geometric displacement for seats and footwell. Complex floor and shell geometry can change actual volume.
- Source
- Spa-volume methodology · verified July 22, 2026
How to use this result
A planning quantity, not an instruction to pour.
Use the label’s application method, protective equipment, maximum dose, spacing, and re-entry directions.
Never combine chemicals. Add one product at a time with circulation as directed.
Start with the staged amount, allow the label-directed circulation time, and measure again.