Power & UPS
Power Consumption Calculator
Turn device wattage and operating time into an electricity-use estimate. Compare a daily total with a 30-day reference and your chosen period. Add your own price per kWh if you want an estimated cost; the calculator does not assume a local electricity tariff.
Your estimate
- Daily energy consumption
- 1.6 kWh
- 30-day reference consumption
- 48 kWh
- Total selected-period consumption
- 48 kWh
Uses constant average wattage and identical devices. The 30-day figure is a reference, separate from your selected period. Cost excludes fixed charges, tiers and taxes not included in your entered price.
Daily energy consumption: 1.6 kWh. 30-day reference consumption: 48 kWh. Total selected-period consumption: 48 kWh
From watts to electricity consumption
Watts measure power at a moment in time. Kilowatt-hours measure energy used over time. This calculator assumes a constant average wattage for identical devices during the hours you enter. Use measured average consumption when available; a power supply's maximum rating is not necessarily the device's typical demand.
Energy and cost formulas
Daily kWh = device watts × hours per day × number of devices ÷ 1,000. Selected-period kWh = daily kWh × days used. The separate monthly reference uses exactly 30 days, not the length of a particular calendar month.
When a price is provided, estimated period cost = selected-period kWh × price per kWh. The currency code labels the amount only: changing USD to EUR does not convert the price or perform foreign exchange. Leave price blank for energy-only results; a price of zero is a valid zero-cost assumption.
Choosing wattage and hours
A desktop can consume different amounts while idle and under load. A NAS may sleep, and a switch may power additional PoE devices. If operation has distinct modes, calculate each mode separately and add the energy totals. Avoid counting the same PoE device load once at the switch and again as an independent mains load.
Hours per day can range from zero to 24. Fractional hours and fractional days are supported for partial operating periods. Device count must be a whole number of at least one. Zero watts or zero hours gives zero modeled energy, not a measurement of standby consumption.
What the cost estimate excludes
Electricity bills may include fixed charges, tiers, taxes, time-dependent rates or other adjustments. The calculator applies one rate to all modeled kWh. Enter a rate appropriate to your purpose, and use separate calculations if the price changes across time periods. No country-specific pricing claims are built into the tool.
Energy use versus UPS runtime
Period energy helps estimate ongoing electricity consumption. UPS backup time requires battery capacity and the instantaneous connected load. Use the UPS Runtime Calculator for outage planning; a monthly kWh figure alone does not determine battery runtime.
Examples
Desktop PC
- Input
- 200 W × 1 device × 8 hours/day × 30 days.
- Result
- 1.6 kWh/day; 48 kWh for 30 days. At an illustrative entered rate of 0.20 per kWh, cost is 9.60 in that rate's currency.
Server
- Input
- 300 W × 1 device × 24 hours/day × 30 days.
- Result
- 7.2 kWh/day; 216 kWh for the period.
Network switch
- Input
- 40 W × 1 device × 24 hours/day × 30 days.
- Result
- 0.96 kWh/day; 28.8 kWh for the period. Include externally powered devices separately where appropriate.
NAS
- Input
- 60 W × 1 device × 24 hours/day × 30 days.
- Result
- 1.44 kWh/day; 43.2 kWh for the period.
CCTV cameras
- Input
- 12 W × 8 cameras × 24 hours/day × 30 days.
- Result
- 2.304 kWh/day; 69.12 kWh for the period. This example excludes recorder demand and power-conversion losses.
Frequently asked questions
What is the difference between W and kWh?
W is power. kWh is energy: a 1,000 W load running for one hour uses 1 kWh. Multiply average power by operating time to estimate consumption.
Is the monthly estimate a calendar month?
No. It is a clearly labeled 30-day reference. Set Days used to the actual number of operating days for your selected-period total.
Can I use my own currency?
Yes. Enter a three-letter currency code and a price per kWh expressed in that currency. The tool labels the resulting cost; it does not convert exchange rates or supply local tariffs.
Does the nameplate wattage equal actual consumption?
Not always. Ratings may describe a maximum or power supply capacity. A measured average appropriate to the workload generally produces a more useful energy estimate.
Why is there no cost result?
Cost is optional. Enter a price per kWh to show it. A blank price leaves the energy results visible without inventing a rate.
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