How much does it cost to run an air conditioner?

A 12,000 BTU inverter (SEER 7) in a typical bedroom: roughly 2.5-3 kWh per day of use, or €0.60-0.75 at €0.25/kWh — about €18-22/month if you run it every day. An older SEER 3.5 unit on the same schedule can double that. Set 26-27 °C, close doors, and shade sunny windows: those three habits often matter more than the brand on the box.

kWh = (watts ÷ 1,000) × hours used per day × days in the period. A 2,000 W oven for 1 hour a day is 2 kWh/day, or 60 kWh/month. Fridges and freezers cycle on and off — use the average power on the energy label (often 100-200 W), not the peak. Multiply the monthly kWh by your tariff to get the cost.

Usually yes — often 30-50% more kWh for the same room, because the exhaust hose leaks heat back in and effective SEER is lower than rated. If you already own a portable, run it with the shortest possible hose and seal the window gap. For daily summer use, a fixed split pays back in electricity within a few seasons.

Your all-in rate per kWh from the last bill — not just the energy component, but network charges and taxes if your supplier shows a single figure. In Italy many households pay €0.22-0.30/kWh in 2025-2026; in the US, $0.12-0.18 is common. Night or off-peak tariffs lower AC cost if you can shift usage, but most cooling happens in afternoon peak hours.