Find out how much an appliance costs to run before the bill arrives. In "From appliance" mode, enter the power rating (W), hours used per day and the electricity price (¥/kWh) to get the cost per day, per month (30 days) and per year (365 days), along with the energy used (kWh/day) and an estimate of CO2 emissions. In "From usage" mode, enter the energy used (kWh) from your meter reading and the price to calculate the cost and CO2. The price defaults to ¥31/kWh as a rough household guide — change it to match your own tariff. CO2 is estimated using 0.45 kg-CO2/kWh. Everything runs in your browser; the numbers you enter are never stored or uploaded.
How to use
- In "From appliance", enter the power (W), hours used per day and the price (¥/kWh) — set the price to your tariff.
- Read the cost per day, per month and per year, plus the energy used and CO2 estimate.
- In "From usage", enter the kWh from your meter reading and the price for the cost and CO2.
FAQ
How is the electricity cost calculated?
Power (W) ÷ 1000 × hours (h) gives the energy used (kWh), which is multiplied by the price (¥/kWh) to get the cost. The monthly figure uses 30 days and the yearly figure uses 365 days.
What is the ¥31/kWh default price?
It is a rough guide for a household tariff. Actual prices vary by provider, plan and time of day, so replace it with the figure from your bill or meter reading.
How is CO2 estimated?
It uses energy used (kWh) × 0.45 kg-CO2/kWh. The real emission factor depends on your provider and energy mix, so treat it as a rough guide.
Are the numbers I enter stored?
All calculation runs in your browser and nothing is sent to a server. Settings like power and price are saved only on your own device to make repeat use easier, and can be cleared with Reset.