Hot tub running cost calculator
Most of a hot tub's power bill is standby heat loss: the energy to replace what leaks out through the cover and cabinet while it sits idle. Enter your numbers for a monthly heating-energy estimate and how hard your heater has to work.
Enter your volume and the outdoor temperature for an estimate.
What is and is not in this number
This estimates the heating energy to hold temperature, modeled as cover-dominant heat loss (loss rises with the gap between your set and outdoor temperature, and with a looser or wetter cover). It does not include the filtration and jet pumps, lid-off heat loss during soaks, or wind, so treat it as a floor for a well-kept tub. The single biggest lever is the cover: a tight, dry, well-fitting cover can cut standby loss dramatically, which is why it pays for itself.
Common questions
Does a bigger heater cost more to run?
No. A bigger heater reaches temperature faster, then cycles off; the energy to hold a temperature is set by how fast heat leaks out, not by heater size. The heater size here just tells you how hard your heater has to work to keep up.
Is it cheaper to turn it down or off between uses?
For frequent use, leaving it at temperature with a good cover is usually most efficient, since reheating a big mass of water from cold takes a lot of energy. For long gaps between soaks, turning it down a few degrees saves more than people expect because loss scales with the temperature gap. Turning it fully off only pays for very long absences.
Why is my real bill higher?
Pumps, frequent soaking with the cover off, wind exposure, and an aging cover all add up. The most common culprit for a creeping bill is a cover that has soaked up water and lost its insulation value.