How this calculator works
Every electrical appliance turns power (watts) into work over time. The energy it uses is simply power × time, and the cost is that energy multiplied by your tariff. The calculator adds the details that make the answer realistic: how many days a week you use the device, how many of them you have, and the standby draw during the hours it is “off”.
Choose a preset from the list to start with typical values (the power and daily hours fill in automatically), then adjust them to match your device. Prices are entered in your own currency; nothing is converted.
The formula
Worked example: a fridge-freezer
A modern A++ fridge-freezer averages about 35 W across the day: the compressor runs perhaps a third of the time at around 100 W. Running 24 hours, 7 days a week, it uses 35 × 24 × 365 ÷ 1000 ≈ 307 kWh a year. At €0.25/kWh that is about €77 a year, or €6.40 a month. On a grid emitting 400 g CO₂/kWh it accounts for roughly 120 kg of CO₂ annually.
Typical power and usage
| Appliance | Typical power | Typical use | kWh / year |
|---|---|---|---|
| LED bulb (9 W) | 9 W | 5 h/day | 16 |
| Wi-Fi router | 10 W | 24 h/day | 88 |
| LED TV 55” | 70–120 W | 5 h/day | 130–220 |
| Fridge-freezer (A++) | 30–40 W avg. | always on | 260–350 |
| Laptop | 30–65 W | 8 h/day | 90–190 |
| Gaming PC (under load) | 300–600 W | 4 h/day | 440–880 |
| Washing machine | ~0.5–1 kWh/cycle | 4 cycles/week | 100–200 |
| Dishwasher | ~1–1.5 kWh/cycle | 5 cycles/week | 260–390 |
| Tumble dryer (vented) | 2–3 kWh/cycle | 3 cycles/week | 300–470 |
| Electric space heater | 2,000 W | 4 h/day in winter | 1,000–1,500 |
| Electric water heater 80 L | 2,000 W | 2–3 h/day | 1,500–2,200 |
| EV home charging | 7.4 kW | 1.5 h/day | 2,500–4,000 |
How to read the results
- Cost per year is the headline figure for budgeting and for comparing a replacement.
- Cost per hour of use helps with decisions such as “is it cheaper to run the dryer or hang the laundry?”
- Wasted on standby appears when you enter a standby draw. It is the money spent while the device does nothing useful.
- CO₂ per year depends entirely on your grid. Change the emission factor to your country’s value to see the real impact.
Tips to cut appliance costs
- Measure, don’t guess. A plug-in energy meter costs less than a single month of a wasteful appliance’s electricity and gives you the true average draw.
- Replace the heat-makers first. A heat-pump dryer uses about half the energy of a vented dryer; a heat pump delivers three to four units of heat per unit of electricity versus one for a resistance heater.
- Kill the standby. Switchable power strips on the TV corner and home office remove standby loads at a stroke. See the standby power calculator.
- Shift to cheap hours. With a time-of-use tariff or solar panels, running the dishwasher, washing machine and EV charging at the right time can halve their cost.
- Mind old fridges. A fridge from the early 2000s can cost €100–150 a year more than a new efficient model, paying back the replacement in a few years.
Limitations
Results assume a constant average power. Devices with strongly variable consumption (heat pumps, air conditioners, induction hobs) depend on weather, settings and usage patterns. For those, use the dedicated calculators or measured data. Tariffs with tiers, standing charges or time-of-use pricing are handled in the electricity bill calculator.
Frequently asked questions
How do I calculate how much electricity an appliance uses?
How much does it cost to run a fridge per year?
Which home appliances use the most electricity?
What is standby power and does it matter?
Is the wattage on the label what the appliance actually uses?
How much CO₂ does running an appliance produce?
Sources & references
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