The short answer
BTU/h describes cooling capacity, while input watts describe electricity use. For a power-and-time cost estimate, use electrical input kW × hours × your electricity price per kWh. Cooling capacity alone cannot supply a reliable input because efficiency and operating conditions also matter.
Cooling capacity is not electrical input
An AC capacity stated in BTU/h describes a rate of heat transfer. Electrical input watts describe how quickly the unit uses electricity. They are different quantities for the cost calculation.
ENERGY STAR describes room AC as moving heat from indoors to outdoors, and lists capacity and CEER as separate specification metrics. A capacity of 12,000 BTU/h does not mean the appliance draws 12,000 electrical watts.
Check the meaning before the unit
| Figure in a specification | Meaning for a cost estimate |
|---|---|
| Cooling capacity in BTU/h | Heat-transfer capacity; do not enter as input watts |
| Cooling capacity in kW | Also heat-transfer capacity; the kW unit alone does not make it electrical input |
| Electrical power input in W or kW | Can support a constant-input estimate for the stated operating point |
| Energy consumption in kWh | Energy over the stated period or measurement |
| CEER, SEER or SCOP | An efficiency metric with its own test basis; not a direct household kWh reading |
Look for the words accompanying the number. “Cooling output 3.5 kW” and “electrical input 1 kW” are not interchangeable, even though both use kilowatts.
Equal capacity can have different input
Consider two illustrative AC specifications with the same stated cooling capacity of 12,000 BTU/h. If one draws 1,000 W at the operating point and the other draws 1,500 W, their continuous hourly electricity costs at $0.20/kWh are $0.20 and $0.30.
The capacity alone does not provide those costs. Nor does that single operating point establish their energy use across every temperature and speed setting.
The AC calculator accepts electrical input power, measured complete-day energy, or a stated annual label energy figure. It deliberately does not infer input power from a BTU/h rating.
Choose a source you can use directly
If the specification clearly provides electrical input for the intended mode, use it with a compatible operating-time assumption. A maximum rating held constant across every enabled hour remains a scenario.
If you have appliance-only accumulated kWh across representative complete days, use measured mode. The energy captured already includes the changing operation inside that sample.
If an annual label kWh figure is appropriate, price it on its stated yearly basis. Do not divide an annual seasonal efficiency metric into a nominal capacity and call the result a measured household input.
Keep cooling and heating separate
Reversible units can have different heating and cooling figures. Choose the correct mode, climate and source boundary for the question you are answering.
Read the EU AC label guide for SEER, SCOP and consumption units. Read monthly and seasonal AC costs to extend a suitable energy source across your own use days.