kWh Cost Per Month
Cost = W × hr/day × 30 / 1000 × $/kWh.
Result
Monthly cost
$7.68
48.0 kWh/mo × $0.16/kWh.
- Wattage200 W
- Hours/day8
- kWh/day1.600
- kWh/month48.00
- Rate$0.16/kWh
- Daily cost$0.26
- Monthly cost$7.68
- Annual cost$92.16
Step-by-step
- kWh/day = W × hr/day / 1000 = 200 × 8 / 1000 = 1.600.
- Monthly = kWh/day × 30 days × $0.16 = $7.68.
How to use this calculator
- Enter wattage (label or kill-a-watt meter).
- Hours used per day.
- Your local rate.
About this calculator
Cost = (watts × hours per day / 1000) × days × $/kWh. US average rate ~$0.16/kWh in 2025. A 200W device run 8 hrs/day: 1.6 kWh/day × 30 days × $0.16 = $7.68/month. Refrigerator: ~$10-15/mo. Always-on plasma TV (or "phantom" loads): $1-3/mo each, adds up to $200+/year across a typical home.
Frequently asked
Device label, manual, or measure with Kill-A-Watt meter ($25). Many "off" devices still draw 1-5W.
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