Cost to run
The purchase price is the number everyone publishes. The monthly bill is the number that decides whether you keep using it.
Across the fifteen competitor pages we examined during research, essentially none published cost-to-run data. It is not a hard number to produce — energy times rate — but it does require stating your assumptions in public, which is the part most publishers avoid.
So here is how we do it, stated once. Cost is kWh consumed times your electricity rate. kWh consumed is rated power times hours times duty cycle— the fraction of that time the element is actually energised, because neither a heater nor a chiller runs flat out once it reaches temperature. The duty cycle is an assumption, we say so on every page, and you can change it.
The default rate is the EIA national average of 18.83 cents/kWh(April 2026), and it is almost certainly wrong for you — the same EIA table puts North Dakota at 12.35 cents and Hawaii at 46.62. That spread is why every calculator here takes your rate as an input instead of printing one national number and calling it your bill.
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Sources
- U.S. Energy Information Administration — Electric Power Monthly, Table 5.6.A — US average residential price, April 2026 (released 2026-06-25). Your utility rate is the number that matters — override the default. (accessed 2026-07-16)