PC electricity cost calculator

How to use

1. Enter the power draw in watts (measured with a watt meter, or assumed), hours per day, and your rate in ¥/kWh. The prefilled rate is only an example (例); use the rate on your bill.
2. Read the monthly and yearly cost.
3. To judge a replacement, compare two setups: the difference and, if you enter a cost, a simple payback in years.

Worked example

Example (all values are examples): 300 W × 4 h/day = 1.2 kWh/day → 36.5 kWh/month, 438 kWh/year. At ¥31/kWh: about ¥1,130 per month, ¥13,580 per year. Replacing with a 200 W setup saves about ¥4,530 per year.

Limits

• A PC’s draw changes with load; one number is a simplification. A measured average is better than a spec-sheet maximum (TDP or PSU rating).
• The rate may be tiered or include fuel-cost adjustments and a base charge; a single ¥/kWh ignores that.
• The payback counts electricity only (not resale value, performance or warranty). A month is 365/12 days.

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