Electricity Power Cost Calculator
Turn equipment watts into monthly and annual electricity use and cost. Enter quantity, hours per day, billing days and your own rate per kWh; cooling and demand charges are excluded.
Result
| Total load | 0.500 kW |
|---|---|
| Monthly energy | 364.80 kWh |
| Monthly cost | $65.66 |
| Annual energy | 4,377.60 kWh |
| Annual cost | $787.97 |
Note: Energy is watts / 1,000 x hours/day x billing days x quantity. Annual figures are 12 times the selected monthly billing period; taxes, demand charges, tiering, power factor penalties, and cooling overhead are excluded.
Learn more
How it works
Electricity is billed by energy in kilowatt-hours (kWh). One kWh is 1,000 watts running for one hour.
Monthly energy = watts / 1,000 x hours per day x billing days x quantity. Multiply by your rate for the monthly cost, and by 12 for the year.
Use the power a device actually draws, not its power supply rating. A server with an 800 W supply often draws 200 to 400 W. A power meter, a smart PDU, or the server's management page (iDRAC, iLO) gives the real figure.
Worked example
One device drawing 500 W, running 24 hours a day, at $0.18 per kWh with 30.4 billing days:
- Energy: 500 / 1,000 x 24 x 30.4 = 364.8 kWh per month
- Cost: 364.8 x $0.18 = $65.66 per month
- Year: 4,377.6 kWh, $787.97
A rack of ten of these costs about $657 a month before cooling.
Does this include cooling?
No. Cooling adds to the bill. Data centers measure this as PUE: a PUE of 1.5 means every watt of IT load costs 1.5 watts at the meter, so multiply the result by your PUE for a fuller figure.
Where do I find my rate?
Your utility bill shows it, usually as cents per kWh. Divide total charges by total kWh to include delivery fees and taxes in one blended rate.
Why 30.4 days?
365 days / 12 months is about 30.4, an average month. Change it to match your actual billing period.
Maintained by the RACKCRUNCH team. Last reviewed September 29, 2026. How we calculate | Report a problem