Air conditioner running cost calculator

Your room

Enter the unit's input power in kW for the most accurate result (found on the spec sheet or energy label). Or enter the cooling capacity in BTU and the unit's EER rating instead.

Input power (kW) optional

Most accurate — use this if available from the spec sheet.

Cooling capacity (BTU) optional

Used with EER when input power is not known.

EER rating optional

Energy Efficiency Ratio — found on the unit's energy label or spec sheet.

Hours used per day

Days used per year

Electricity rate (p/kWh)

Pre-filled with the current Ofgem price-cap rate. Adjust if you're on a different tariff.

Use my postcode for a regional rate and carbon estimate

Optional. Your postcode is checked by Postcodes.io; only its outward part is sent to NESO for regional electricity-carbon data. We do not store it.

UK postcode

Result

Enter the unit's power in kW, or its cooling capacity and EER, to see running costs.

How we calculated this

Formula: Input power (kW) × hours per day × days per year × rate (£/kWh)

When input power is not available, it is derived from cooling capacity and EER: Input power = Cooling capacity (W) ÷ EER, where cooling capacity in watts = BTU ÷ 3.412.

Based on the Ofgem average direct-debit unit rate for 2026-07-01–2026-09-30, last checked 2026-08-28. Source: https://www.ofgem.gov.uk/information-consumers/energy-advice-households/energy-price-cap-unit-rates-and-standing-charges

How much does air conditioning cost per hour?

At 26.11p/kWh, a 9,000 BTU portable air conditioner with an EER of 2.5 running at rated power for 8 hours a day over 90 days would cost about £198. A thermostat may cycle the compressor off once the room reaches temperature, so actual consumption can be lower; poor sealing, hot weather and an undersized unit can keep it running for longer.

The most reliable figure is the unit's electrical input in watts, not its advertised BTU capacity. For example, at 26.11p/kWh, a 1 kW unit costs about £0.26 per hour at full input. Use your own tariff above if it differs from the Ofgem average.

What the estimate includes

Electricity used by the air conditioner at the input power you enter.
Your daily hours and annual days of use.
The unit rate shown in the calculator, which you can replace with your tariff.

It does not predict compressor cycling, heat leaking through an unsealed window, standby consumption or future carbon intensity. The optional postcode lookup can apply Ofgem's current regional direct-debit rate, but the standing charge is excluded because owning an air conditioner does not create an additional standing charge. Read the full UK running-cost guide for worked examples and ways to reduce consumption.

Not sure what size unit you need? Use the BTU calculator first. Comparing two units on efficiency and purchase cost? Try the efficiency comparison calculator.