CalcBeast

Air Conditioning Running Cost Calculator

Find out what your air conditioning unit costs to run in the UK — per hour, per day, and across the summer months. Works for portable units and split systems using your own electricity unit rate. The per-year figure assumes continuous year-round use; most people only run AC in summer, so scale the annual cost to the months you actually use it.

Per hour to per season · Portable & split · UK p/kWh

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W

Use the unit's power input (W), not its cooling capacity (BTU). Portable units ~1,000–1,400 W; splits 1,500–5,000 W.

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Quick facts
  • AC power draw (W) is the electrical input, not the cooling output. A unit rated at 3,500 BTU cooling capacity might only draw 1,000 W — check the spec sheet or rating plate for the wattage figure to enter here.
  • Portable units (1,000–1,400 W) are cheaper to buy but less efficient per BTU of cooling than split systems. A split AC delivering the same cooling often draws significantly less power.
  • AC is seasonal in the UK. Most households run it for a few weeks to months each summer — the per-year figure above assumes continuous use, so divide it by 12 and multiply by the months you actually use it for a realistic seasonal cost.
  • Cost per hour scales directly with unit size. A 1,000 W portable costs about 24–25p/hr at current rates; a 5,000 W unit costs five times as much. Matching unit size to room size avoids paying for capacity you never use.
Quick answer

How much does air conditioning cost to run in the UK?

Multiply the AC unit's power draw in kW (watts ÷ 1000) by your electricity unit rate in pence. That gives you pence per hour. Divide by 100 for pounds. A 2,000 W unit at 24.5p/kWh costs about 49p per hour — or roughly £2.94 for 6 hours a day.

The per-year figure in the calculator assumes continuous year-round use. For a seasonal estimate, multiply the per-day cost by the number of days you actually run the unit each year — most UK households use AC for a few weeks to three months in summer.

Portable vs split AC

Power draw by AC type

Always enter the electrical power draw in watts — found on the rating plate or in the product manual — not the cooling capacity in BTUs. A unit marketed as "12,000 BTU cooling" might draw anywhere from 900 W to 1,400 W depending on its efficiency rating.

Split systems are typically more efficient: they deliver more cooling per watt than portable units because they vent heat directly outside rather than through a warm exhaust hose inside the room.

FAQ

Frequently asked questions

How much does air conditioning cost to run per hour in the UK?

At 24.5p/kWh, a 1,000 W portable AC costs about 24.5p per hour to run. A 2,000 W unit costs roughly 49p per hour, and a 3,500 W split system costs about 86p per hour. The formula is simply: power in kW × unit rate in p/kWh = pence per hour. Use the calculator above to enter your own wattage and electricity rate.

How much does it cost to run air conditioning for a day?

A 2,000 W unit running 6 hours a day costs about £2.94 per day at 24.5p/kWh (2 kW × 6 hrs × 24.5p ÷ 100). A more efficient 1,000 W portable for the same 6 hours would cost around £1.47 per day. Reducing daily hours is the fastest way to cut costs.

Is air conditioning expensive to run in the UK?

It depends on the unit size and usage hours. A portable AC at 1,000 W used 4 hours a day costs around £1 a day or roughly £30 across a hot month — not enormous, but it adds up quickly if the unit is larger or used for longer. A 3,500 W split system running 8 hours a day in a hot spell costs about £6.86 a day. Compared with other high-power appliances, AC sits alongside tumble dryers and electric heaters in terms of hourly cost.

Do portable air conditioners cost more to run than split systems?

Portable units tend to be less efficient: they typically draw 1,000–1,400 W but deliver fewer BTUs of cooling per watt than a split system. A split AC delivering the same cooling output might draw only 800–1,200 W, costing noticeably less per hour. Over a summer of use the difference can be meaningful. Portables win on upfront cost and flexibility; splits win on running cost efficiency.

How much does air conditioning cost for a UK summer?

A rough estimate for a typical UK summer (June–August, say 12 weeks): a 2,000 W unit used 5 hours a day, 5 days a week, at 24.5p/kWh would cost about 2 × 5 × 24.5 ÷ 100 × 5 × 12 = roughly £147 over the season. Adjust hours and days to match your own pattern using the calculator above. Most UK households find seasonal AC costs are modest compared with heating costs in winter.

Does a fan cost less to run than air conditioning?

Yes — significantly less. A tower fan or pedestal fan typically draws 30–80 W. At 24.5p/kWh, an 80 W fan running 6 hours costs about 11.8p a day, compared with £2.94 for a 2,000 W AC unit. A fan does not cool the air — it only moves it across your skin — so it is far less effective in extreme heat, but it is roughly 25× cheaper to run hour for hour.

How can I cut my air conditioning running costs?

The most effective steps: (1) Pre-cool the room and then turn the unit off — AC is most efficient at full power for a short burst rather than trickling all day. (2) Keep doors and windows closed while the unit is running. (3) Use blackout blinds or curtains to reduce solar gain. (4) Set the thermostat to 24–26°C rather than 18°C — each degree lower meaningfully increases energy use. (5) If buying new, choose an inverter-driven split system over a portable unit for the same room — far better efficiency per pound of running cost.