How it works
A walkthrough, end to end.
- 1
Enter the device's power (watts) and hours used per day.
- 2
Enter the electricity rate per kWh.
- 3
See daily, monthly, and yearly cost.
Reference
Energy cost
kWh/day = watts × hours / 1000. Cost = kWh × rate.
Use cases
What you can do with this.
AC running cost
How much does an 8000 BTU window AC cost monthly?
Mining rig
Estimate GPU or ASIC monthly draw.
Server / PC
Annual cost of leaving a desktop on 24/7.
EV charging
kWh × per-kWh rate for home charging.
Lighting comparison
LED vs incandescent over the year.
FAQ
Frequently asked.
Check your utility bill — often $0.10–$0.35 per kWh in the US.
Many devices draw 1–10 W in standby. Add a small constant if relevant.
No. All math runs in your browser.
Compute peak and off-peak hours separately and sum.