How much does your electricity actually cost?
Every appliance in your home has a running cost. Some are trivial (a phone charger costs cents per year), others are surprisingly significant (a 15-minute daily hot shower on an electric water heater can rival your whole lighting bill). This calculator turns wattage and usage into real money — daily, monthly, and yearly — in your currency at your electricity rate.
How to use this calculator
Two modes cover both common questions:
- Single appliance — pick or enter one device, its usage per day, and get the cost. Use this for the “should I keep this space heater running?” or “how much does my aquarium cost per month?” questions.
- Multiple appliances — build a list of devices with their usage patterns. Get the total and see which items dominate your bill. Use this to audit a room or a whole household.
Set your currency and per-kWh rate once at the top — both modes use the same setting.
The formula
The calculation itself is simple:
cost = (power in watts × hours per day / 1000) × rate per kWh
The division by 1000 converts watts to kilowatts (kW), and multiplying by hours gives kilowatt-hours (kWh) — the unit your electricity bill uses. Multiply by the price per kWh and you have the cost.
Example: a 2500 W clothes dryer running 1 hour per day, at €0.25/kWh:
- Energy per day: 2500 × 1 / 1000 = 2.5 kWh
- Cost per day: 2.5 × €0.25 = €0.63
- Cost per month: about €19
- Cost per year: about €228
Getting your electricity rate right
Your kWh rate is on your electricity bill, but check carefully — many bills show a base rate plus distribution fees, transmission, taxes, and VAT. For a realistic cost, use the final total divided by kWh consumed, not just the energy component.
Typical residential rates as of 2026:
- Europe: €0.20–0.45 per kWh (Germany highest, France and Poland lower)
- United States: $0.10–0.35 per kWh (California and Hawaii highest, Louisiana lowest)
- UK: £0.25–0.30 per kWh under current price caps
- Australia: A$0.28–0.40 per kWh
If you’re on a time-of-use tariff (peak vs off-peak), calculate with the peak rate for a conservative estimate, or split usage between rates for accuracy.
The standby power trap
Many “always on” appliances draw meaningful power even when they seem off:
- TVs (LED) — 1–5 W standby, sometimes higher on smart TVs with always-listening features
- Gaming consoles — 5–15 W in standby (PS5, Xbox with “rest mode” for downloads is higher)
- Cable boxes / set-top boxes — 15–25 W continuously, one of the worst offenders
- Microwaves and coffee makers — 1–3 W for the clock display
- Chargers left plugged in — usually under 0.5 W each, but multiplied across many chargers
A single 15 W set-top box left on 24/7 costs about €33 per year at €0.25/kWh. This calculator’s standby toggle lets you split active and idle power to see the actual breakdown.
Appliance wattage estimates
The calculator includes presets for 40+ common appliances with typical average wattages. These are best-effort averages — actual power depends on model, mode, and load:
- A “1800 W dishwasher” only draws that during the heating stages of the cycle; average energy per cycle is much less
- A “100 W fridge” is the average as the compressor cycles; while running it’s 150–200 W, and it may only run 30–50% of the time
- A “2000 W air conditioner” draws that at maximum; it modulates significantly at lower cooling loads
For high-accuracy measurement on a specific appliance, buy a plug-in power meter (also called an energy monitor or “kill-a-watt”). They cost €15–25, log actual kWh over hours or days, and give you exact numbers. Especially worth it for appliances you suspect are eating your bill (old fridges, aquarium equipment, home servers, etc.).
What drives most household bills
The biggest energy consumers in a typical household, roughly in order:
- Space heating (if electric or heat pump) — often 40–60% of the bill in cold climates
- Water heating (if electric) — 15–25% of the bill
- Air conditioning (in warm climates) — 15–40% in summer
- Refrigeration (fridge + freezer) — 5–15%, always-on so it adds up
- Laundry (mainly the dryer) — 5–10%
- Cooking (electric hob/oven) — 3–8%
- Lighting — 1–3% with LEDs (used to be much higher with incandescents)
- Consumer electronics + standby — 3–8% (higher than most people realize)
If you’re trying to reduce your bill, the multi-appliance mode helps identify which categories to focus on. Small savings on a fridge that runs 24/7 add up faster than heroic effort on lights.
Important limitations
- Not usage tracking — this calculates cost based on your inputs. For actual measurement, a smart meter or plug-in energy monitor logs real usage.
- No time-of-use pricing — the calculator assumes a flat rate. If you have peak/off-peak or dynamic tariffs, calculate each period separately.
- No fixed / standing charges — your bill probably has a fixed monthly fee separate from usage. The calculator only handles the variable per-kWh cost.
- No renewable / self-consumption offset — if you have solar panels, some of your consumption is offset by generation. Calculate cost based only on the grid-imported portion.
- Averages, not maxima — a “2500 W dryer” may briefly spike higher during startup or heating; use average power for cost estimates, peak power for wire sizing.
For serious energy auditing, combine this calculator with a real usage monitor and your utility’s data. But for “should I keep this thing plugged in?” or “how much would replacing this cost per year?” — the numbers here are close enough to make good decisions.