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Server Energy Cost Calculator

Enter power draw, hours per day, and price per kWh to find the running cost.

Result

$59.13
$4.93
$0.16
394.20 kWh

How it is calculated

The engine converts power to energy and then to money. Daily energy is kWh/day = W / 1000 × h, where W is the average power draw in watts and h the hours running per day. Yearly energy is kWh/day × 365. With r, the price of one kWh, the daily cost is kWh/day × r, the yearly cost is kWh/year × r and the monthly cost is the daily cost times 30.4375, the average length of a month. If hours is left empty the tool assumes 24; hours must be between 0 and 24, otherwise there is no result. Watts and price cannot be negative, and the price has to be filled in. Amounts are shown in dollars, so enter the price in the same currency unit per kWh.

Worked example

A home server draws an average of 45 W, runs around the clock and costs 0.15 per kWh. Daily energy is 45 / 1000 × 24 = 1.08 kWh. Over a year that is 1.08 × 365 = 394.20 kWh. The yearly cost is 394.20 × 0.15 = $59.13. The daily cost is 1.08 × 0.15 = $0.16 (rounded from 0.162), and the monthly cost is 0.162 × 30.4375 = $4.93.

Try this example →

Common mistakes

  • Entering the power supply rating instead of the average draw. A 450 W supply feeding a machine that idles at 40 W would overstate the bill about ten times; measure with a plug-in meter if possible.
  • Entering the price per kWh in cents. Typing 15 instead of 0.15 gives $2,463.75 where the true answer is $59.13 for the same 45 W server.
  • Leaving hours empty and forgetting that the tool then assumes 24. For a machine that runs only 10 hours a day, the cost would be overstated by more than half.
  • Entering more than 24 hours per day. A day has only 24 hours, so a value above 24 (or below 0) returns no result.
  • Ignoring other costs. The result covers electricity only, not extra cooling, a UPS loss, a fixed supply charge or time-of-day rates, which can change the real bill.

About this calculator

Electricity cost follows a simple relationship: energy (kWh) = power draw (W) ÷ 1000 × hours running, and multiplying that by your utility's price per kWh gives the cost for any period. Since a home server, NAS, or router typically runs 24/7 rather than a few hours a day like most appliances, even a modest 30–50 watt draw adds up to a meaningful yearly bill once you extrapolate daily use to a full year.

This calculator takes your device's wattage, daily runtime, and local electricity rate and breaks the cost down into daily, monthly, and yearly figures alongside total energy consumed. Home-lab and self-hosting enthusiasts use it to compare the running cost of an always-on Plex server, NAS, or Raspberry Pi cluster against cloud hosting, while small office and IT admins use it to budget for always-on network equipment.

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Comments (1)

  • Editorial team

    The number that matters most is the watts you type. A power supply's rating is a ceiling, not what the machine draws, so a plug-in meter reading averaged over a normal day gives a far better input. As a check, a steady 100 W comes to 876 kWh a year. Cooling, a UPS and rack overhead are not added, so raise the watts if you want them counted. What average draw does your server show on a meter?

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