Electricity consumption calculator
Estimate what a device really consumes: power, hours of use and the price per kWh give the consumption in kWh and the cost per month and per year. A 1 500 W appliance running one hour a day is 1.5 kWh, about 0.50 € a day; a 10 W standby draw adds up to roughly 88 kWh, or 30 €, a year. It is the plain arithmetic of an energy bill, run on your device.
- 100% local
- Free · no account
- Instant result
This tool runs entirely in your browser — nothing is sent to a server.
An appliance’s consumption is simple to compute: power (in watts) × hours of use ÷ 1000 = kilowatt-hours. A 1,500 W appliance used for one hour consumes 1.5 kWh — roughly €0.50 at current Belgian electricity prices.
This calculator converts power and usage time into kWh and into euros per month and per year. Test your most-used appliances: space heater, tumble dryer, fridge, console on standby — the results often surprise.
How it works
Type the figures or drop the file you want to process — the tool checks them as you go.
Everything is computed directly in your browser. Nothing is sent to a server.
The result appears instantly, with the detailed breakdown ready to copy, download or keep.
Why use this tool
No account, no download, no limit: the result appears as soon as you enter your data.
Every rule, algorithm and check reflects what we use ourselves every day at Flexina.
The calculations follow the official standards, and the step-by-step detail lets you double-check the outcome.
What does running it locally bring you?
Files, figures and documents never leave your device: nothing is stored, nothing is sent.
Once the page is loaded, you can cut the network: the tool keeps working.
No upload, no account, no third-party server in between: results stay fast and fully private.
Frequently asked questions
Where do I find my appliance’s power?
On the nameplate (on the back or under the appliance), in watts (W) or kilowatts (kW). For appliances with variable consumption (fridge, washing machine), the energy label states kWh per year or per cycle instead.
What price per kWh should I use?
The all-in price on your bill (energy + grid + taxes), generally between €0.30 and €0.40/kWh in Belgium and around €0.25/kWh in France (regulated tariff). Divide your annual bill by the kWh consumed to get it precisely.
Do standbys really matter?
A continuous 10 W standby represents 88 kWh per year, about €30. Multiply by the number of appliances: standbys often weigh 5 to 10 % of a household bill.