Get your actual number
The operating-cost calculator takes your system's capacity and efficiency (SEER2/HSPF2 - on every model page in our database), your state's average electricity rate (we load current EIA figures), and your usage pattern, and returns monthly and annual estimates. That's the whole answer; the rest of this page explains what drives it.
What actually drives the bill
- Runtime, not size. An inverter mini split sips power most of the day at partial speed. The rated wattage on the spec sheet is a ceiling, not the draw - which is why "how many watts" is the wrong question and seasonal efficiency (SEER2 for cooling, HSPF2 for heating) is the right one.
- Heating is the bigger line item in cold climates - not because the unit is inefficient, but because winter asks for more hours and harder work. Efficiency falls as temperature falls; the calculator's climate-zone adjustment covers that.
- Your rate matters as much as your unit. The spread between low-rate and high-rate states means identical systems produce very different bills - a big part of why payback math is so local (payback calculator).
- Sizing and habits. Oversized units cycle inefficiently (why); dirty filters tax every hour of runtime; setpoint set-and-forget beats aggressive swings with inverters.
Compared to what you're replacing
Against electric resistance heat (baseboards, space heaters), a heat pump delivers the same warmth for a fraction of the electricity - that ratio is what the COP/HSPF2 figures on our model pages express. Against window ACs, modern mini splits carry substantially higher seasonal ratings. Against gas heat, the comparison is rates versus therms - genuinely local math; run the payback calculator rather than trusting any national claim, including ours.
Reading the ratings on our pages
- SEER2 - seasonal cooling efficiency; higher = less electricity per cooling season.
- HSPF2 - the heating equivalent (we show Region IV, the national test standard; Region V, where published, reflects colder climates).
- Verified badges - every rating on our model pages traces to a manufacturer document or AHRI certificate, because efficiency claims are exactly where marketing rounds up.