Energy cost calculator
Work out what an appliance really costs you per day, month and year — and how much of that disappears into standby. Free and entirely in your own browser.
Check your energy contract — tariffs vary.
What it costs you
- Energy use
- —
Standby waste
Presets are typical estimates; every field is editable. Real use varies per model and household.
Calculated in your browser — nothing is stored or sent.
How it works
1. Pick an appliance
Choose a preset for typical values, or enter the power draw in watts yourself.
2. Enter usage and price
How many hours a day is it on, and what do you pay per kWh? Don't forget standby.
3. See what it costs
You instantly get the cost per day, month and year — and how much of it is standby.
Want to measure usage per appliance instead of estimating it? Smart plugs plus a local Home Assistant setup show it live — no subscription. See also the Zigbee channel planner.
Frequently asked questions
How is the cost calculated?
Simply and transparently: power (watts) × time (hours) gives energy in kWh, which we multiply by your electricity price. Standby is charged over the remaining hours of the day. There are no hidden factors — you can check the maths by hand.
What exactly is standby waste?
Many appliances draw power even when you're not using them: a TV on standby, a charger left plugged in, a console with 'quick start' enabled. It's often just 1 to 10 watts — but 24 hours a day. This tool shows what that costs per year.
Are the preset values right for my appliance?
They're average estimates for a Dutch household — useful as a starting point, but real usage varies by model and habits. Every field is editable. To know exactly, measure it with a smart plug that has energy monitoring.
Is my data stored?
No. The calculation runs entirely in your own browser. Nothing is stored or sent.
Want usage tracked automatically?
We make your home smart with Home Assistant, Zigbee and Matter — including per-appliance energy monitoring. Local, no subscription.