Air Conditioner Power Consumption Calculator
Calculate how much electricity your air conditioner uses and what it costs to run. Enter BTU/h capacity, EER efficiency rating, and daily running hours to see kWh and monthly cost.
Calculate AC Power Consumption
Check AC nameplate or energy label
AC Power & Cost
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Power Draw (Watts)
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Daily Usage (kWh)
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Daily Cost
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Monthly Cost
Formulas
From BTU/h and EER:
Power (W) = BTU/h ÷ EER
kWh/day = Power (W) ÷ 1000 × hours
kWh/day = Power (W) ÷ 1000 × hours
AC Size Conversion:
1 ton = 12,000 BTU/h ≈ 3.517 kW of cooling capacity
AC Efficiency Reference
| AC Size | BTU/h | Watts (EER 10) | Watts (EER 12) |
|---|---|---|---|
| 0.75 ton | 9,000 | 900 W | 750 W |
| 1 ton | 12,000 | 1,200 W | 1,000 W |
| 1.5 ton | 18,000 | 1,800 W | 1,500 W |
| 2 ton | 24,000 | 2,400 W | 2,000 W |
| 3 ton | 36,000 | 3,600 W | 3,000 W |
Frequently Asked Questions
How do I calculate AC power consumption?
For window/portable units: Power (W) = BTU/h ÷ EER. For split systems: the kW input is usually on the nameplate. Then: daily kWh = Watts ÷ 1000 × hours running. Example: 18,000 BTU/h, EER 12 = 1,500W. Running 10 hours/day = 15 kWh/day × $0.15 = $2.25/day or ~$67/month.
What is EER and SEER?
EER (Energy Efficiency Ratio) is cooling output (BTU/h) divided by power input (W) at a fixed test condition. SEER (Seasonal EER) averages over a full cooling season including part-load and varying outdoor temperatures — a better real-world indicator. Modern inverter split systems often achieve SEER 20–30+, compared to 8–12 for older fixed-speed units.
How many watts does a 1-ton AC use?
1 ton = 12,000 BTU/h. Power depends on EER: EER 8 → 1,500W, EER 10 → 1,200W, EER 12 → 1,000W, EER 15 → 800W. Inverter ACs modulate their compressor and can run as low as 200–400W at light load. This is why inverter ACs save 30–50% energy compared to fixed-speed units of the same capacity.