How do you calculate AC electricity cost?
Rough planning formula: kWh = (BTU/hr × hours) ÷ (SEER × 1,000). Multiply kWh by your $/kWh rate. Real bills vary with outdoor temperature, thermostat setpoints, and cycling.
AC Cost to Run Calculator
Estimate what it costs to run an air conditioner from SEER (or EER), capacity, hours, and your electric rate. Useful for comparing window units, portable ACs, and mini-splits before you buy.
Your estimate
- Capacity
- 12,000 BTU/hr
- Monthly kWh
- 180.0
- Cost / day
- $0.90
- Cost / month
- $27.00
- Season (120 days)
- 720.0 kWh · $108.00
vs SEER 22: save about $7.36/month · $29.45 over the season.
Formula: kWh ≈ (BTU/hr × hours) ÷ (SEER × 1,000). Planning estimate only — not a utility bill.
How SEER turns into a bill estimate
Cooling energy use scales with BTU capacity and hours of operation, then divides by efficiency (SEER/EER). Higher SEER means fewer kWh for the same cooling — enter your utility $/kWh for a local monthly estimate.
Size the unit first with the BTU calculator or mini-split calculator; an oversized short-cycling unit can cost more than a right-sized efficient one.
Hours and climate matter more than sticker SEER
A high-SEER unit in a mild climate with short cooling seasons may cost less annually than a mid-SEER unit run 12 hours a day in a hot region. Use realistic daily hours for your home, not nameplate maximum.
Planning a ductless install? Walk electrical, placement, and kit choices in the DIY mini-split project roadmap.
What this estimate leaves out
We model compressor energy for planning — not standby power, fans on other equipment, or time-of-use rate tiers. Treat the result as a comparison tool between units, not a utility bill guarantee.
Related guides
Frequently asked questions
Is SEER the same as SEER2?
No — SEER2 uses updated test conditions and usually reads lower than old SEER for the same hardware. Enter the number on your equipment label; do not mix SEER and SEER2 in one comparison without converting.
Does a higher SEER always save money?
Higher SEER cuts run cost for the same hours and capacity, but the upgrade premium may take years to recover. Use the compare SEER field to see monthly savings before you buy.
Related calculators
HVAC Calculators · https://hvaccalculators.net/ac-cost-to-run-calculator/