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AC operating cost
Updated August 5, 2026 · tariffs verified August 4, 2026 · by Cali Energy
How much does it cost to run AC in California? A typical 3-ton central AC (about 3,000 W) running 8 hours a day uses roughly 24 kWh — about $8 a day (~$245/mo) at SCE’s 34¢ off-peak rate, rising to about $14 a day (~$418/mo) at the 58¢ 4–9 p.m. peak. Cost scales with size, efficiency (its EER2 rating), run-time and your rate.
✓ Built on the standard cooling-power formula (BTU/h ÷ EER2) and published 2026 LADWP & SCE rates. See the exact figures it uses ↓
Cali Energy calculation · design-condition estimate · illustrative, not a quote
Watts are estimated as BTU/h ÷ EER2 at design conditions — a peak-load approximation. Real-world average draw is lower because the compressor cycles and modulates. For an exact figure, use the equipment documentation, a permanently installed energy monitor, or a measurement by a qualified HVAC/electrical professional. Rates are illustrative 2026 examples shown before any baseline credit; your actual rate and plan may differ.
The rates and figures this calculator usestap to verify
The calculator multiplies your AC’s power draw by its run-time and the rate you pick. Here is every figure it uses — the rate menu (illustrative 2026 examples) and the formula — each rate linked to its utility.
| Tier 1 summer, per kWh | 26.4¢ |
| Tier 3 summer, per kWh | 41.0¢ |
| Summer off-peak, per kWh | 34¢ |
| Summer 4–9 p.m. peak (TOU-D-4-9PM), per kWh | 58¢ |
| Summer 5–8 p.m. peak (TOU-D-5-8PM), per kWh | 74¢ |
| Full-load power draw | Watts = BTU/h ÷ EER2 |
| Daily energy | kWh/day = Watts ÷ 1000 × hours/day |
| Monthly cost | = daily cost × 30 |
The rate menu shows illustrative 2026 examples for comparison, not your exact tariff — confirm current numbers on the linked utility pages. Power is estimated at full load from the standard BTU/h ÷ EER2 relationship; a real AC cycles and averages less.
Example results you can reproduce
For a 3-ton central AC (about 3,000 W) at EER2 12 running 8 hours a day — 24 kWh a day — here is the cost on three illustrative rates. Enter the same values above to reproduce them.
| Electricity rate | Cost per day | ~Cost per month |
|---|---|---|
| LADWP Tier 1 (26.4¢) | $6.34 | $190.15 |
| SCE off-peak (34¢) | $8.16 | $244.80 |
| SCE 4–9 p.m. peak (58¢) | $13.92 | $417.60 |
How this calculator works
It estimates full-load power as BTU/h ÷ EER2 — a 3-ton (36,000 BTU/h) unit at EER2 12 draws about 3,000 watts. That draw × your run-time gives kilowatt-hours per day, and kWh × the rate you pick gives the cost; monthly is daily × 30. It is a peak-load figure: a real air conditioner cycles on and off, so its average draw — and your real bill — is usually lower.
How to read your result
You get four numbers: approximate full-load watts, kWh per day, cost per day and an approximate monthly cost. Treat them as the upper end for continuous running at the rate you chose. If your AC runs only part of each hour, or you cool during cheaper off-peak periods, your actual cost lands below the peak-rate figure.
What moves the result the most
Four inputs dominate: unit size (tons/BTU), efficiency (a higher SEER2/EER2 cuts watts for the same cooling), hours per day, and — often the biggest swing — the rate. The same 3-ton unit costs roughly 2.2× more at SCE’s 58¢ peak than at LADWP’s 26¢ Tier 1, which is why shifting cooling out of the 4–9 p.m. window matters on time-of-use plans.
Common questions
What size is my AC?
Look for the tonnage or BTU/h on the outdoor condenser’s nameplate, or read the model number — a “036” usually means 36,000 BTU/h (3 tons). Most single-family homes run 2–5 tons.
Should I enter SEER2 or EER2?
Enter EER2 (the full-load efficiency), which is what the watts formula uses. SEER2 is a seasonal average and runs higher; as a rough guide, EER2 is often around 0.85–0.9 of the SEER2 number.
Why is my real cost lower than this?
Because the tool prices full-load, continuous running. A real AC cycles off once the house is cool, so its average draw — and cost — is typically well below the figure shown.
Which rate should I choose?
Pick the one that matches when you cool. On SCE time-of-use, 4–9 p.m. cooling is priced at the peak rate; earlier or overnight cooling uses the cheaper off-peak rate. LADWP customers pick their tier.
Can solar or a battery cut this cost?
Yes — daytime solar can cover midday cooling directly, and a battery can run the AC through the expensive evening peak on stored power. Use our battery-sizing tool to size that.
Sources
- DOE / ENERGY STAR — central AC SEER2 requirements
- LADWP — Consumer Rebate Program
- SCE — Rebates & Marketplace
- CEC — Building Climate Zones
Estimates only, not a quote. Assumptions, rates, incentives and program rules can change — confirm current details with your utility, the program administrator or a licensed professional.
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