Air-conditioner cost calculator
Work out how much it costs to run a portable or window air-conditioning unit, from its power rating, usage and your electricity price.
Result
Cost per year
Cost per week
How to use this tool
- Check the unit's power label or manual. The prefilled wattage is an example, not a model-specific value.
- Enter how many hours a day and days a week you run it.
- Enter your electricity price per kWh.
- Read the estimated cost per week and per year.
Assumptions
- Assumes the unit runs at full rated power the whole time it's on — a thermostatically controlled unit cycling on and off will typically cost less than this in practice.
- The annual figure repeats the entered weekly use for 52 weeks. Scale it to your actual cooling season if you use the unit for fewer weeks.
Technical details: what the fields mean
- AC unit power
powerWatts - Rated power from the specific unit's label or manual; the prefilled value is illustrative.
- Hours per day
hoursPerUse - How many hours a day it actually runs.
- Days per week
daysPerWeek - How many days a week you use it — often seasonal, so estimate for the months you actually run it.
- Electricity price
pricePerKwh - Your electricity price per kWh.
Methodology
Energy per week = power (kW) × hours per day × days per week. Weekly cost = energy × your entered electricity price per kWh; the yearly estimate repeats that weekly use for 52 weeks. Costs are displayed in GBP (£), with no live tariff lookup or currency conversion.
Worked example
Illustrative 1000W unit, 4 hours/day, 7 days/week at an entered rate of 27p/kWh
Inputs: AC unit power: 1000 W, Hours per day: 4 hours, Days per week: 7, Electricity price: £0.27/kWh
Result: £7.56/week, £393.12/year. Replace the sample inputs with the unit rating and tariff you use.
Practical guidance
- Running a unit only when needed (with a thermostat or timer) rather than continuously cuts real-world cost well below this estimate.
- Use your measured or expected running hours for the room; the calculation does not infer cooling demand from room size or insulation.
Common mistakes
- Treating the full-year projection as realistic for a purely seasonal appliance — scale it to the months you actually use it.
- Ignoring that a thermostatic unit cycles on and off rather than running continuously at full power.
FAQs
Does this include the electricity standing charge?
No. It estimates the appliance's usage-related cost from the power, time and unit price you enter.
Last reviewed: 2026-10-11
Assumes the selected power is drawn for the entered hours; thermostat cycling and seasonal variation are not modeled.
This tool provides an indicative estimate, based on the assumptions stated above.
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