Appliance Energy Cost Calculator
Turn appliance watts and daily operating time into monthly energy use and electricity cost.
Currency selection changes the unit label, not an exchange rate. Enter every price in the selected currency.
How to choose the inputs
Use the average power during the entered operating hours. A label stating maximum power is not necessarily average consumption. For a cycling device, either measure average watts or enter equivalent full-power hours, but do not adjust both.
Formula and measurement boundary
Three worked scenarios
These are fixed hypothetical examples, not live tariffs or verified product data. They use EUR and kilometres where applicable and do not change with the form settings. Only the table input changes.
Unchanged inputs
- Appliance power: 100 W
- Days per month: 30
- Electricity price: 0.25 EUR/kWh
| Hours used per day | Estimated result |
|---|---|
| 4 h | €3.00/month |
| 8 h | €6.00/month |
| 12 h | €9.00/month |
The examples consume 12, 24 and 36 kWh per modelled month. With 30 days entered, the annual estimate represents 360 operating days, not automatically a 365-day calendar year.
What this result does not establish
- The annual view repeats the same month; seasonal use is not simulated.
- Standby consumption outside the entered hours needs a separate calculation.
- The price excludes fixed charges unless you deliberately allocate them yourself.
Use energy over a cycle for appliances that turn themselves on and off
The following are additional hypothetical decision examples. Separately discussed fees, reserve allowances or running costs are not automatically added to the form result.
A 2 kW heater running continuously for three hours uses 6 kWh. At €0.25/kWh that costs €1.50. A refrigerator with a 150 W compressor does not necessarily use 3.6 kWh every day: it cycles. If a plug-in meter records 0.9 kWh across 24 hours, its average draw is 37.5 W and daily cost at the same tariff is €0.225. Enter that average power with 24 hours rather than the compressor’s peak.
For a washing machine, dishwasher or dryer, a per-cycle meter reading is more useful than rated watts. Compare the same programme, load and settings. A 1.2 kWh cycle performed 15 times per month uses 18 kWh; the frequency matters as much as the programme. Standby consumption belongs in the remaining hours, not in the active-cycle estimate.
Use the variable electricity price from the bill when estimating the saving from using the appliance less. A fixed monthly supply fee normally remains payable and should not be attributed to each avoided kWh. Repeat measurements across representative conditions before annualising them; a single summer day does not establish a refrigerator’s full-year consumption.
Sources and their scope
- EIA: measuring electricity — Power and energy units only; not equipment performance.
These reference pages were accessed on 21 September 2026. The equations and examples are the site’s own model; these sources do not certify its defaults or results.
Frequently asked questions
What if I know measured daily kWh?
Convert to average watts: daily kWh × 1000 / 24, then enter 24 hours per day.
Why use a meter?
It captures how your device actually operates during the measured period rather than assuming nameplate power all day.
Read the model and verification limits