PUE and Energy Cost Calculator
See facility load, overhead power and the yearly energy bill for any IT load and PUE.
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How to Use It
Enter your IT load, slide the PUE and add your power price. The calculator shows what the facility draws in total and how much of the energy bill goes to overhead like cooling and power losses.
How This Calculator Works
The calculator runs these formulas in your browser:
- Facility load (kW) = IT load (kW) × PUE
- Overhead (kW) = facility load − IT load
- Energy per year (MWh) = facility load × 8,760 ÷ 1,000
- Energy cost per year = MWh × price ($/MWh)
- Overhead cost = overhead (kW) × 8,760 ÷ 1,000 × price
Default assumptions and sources
PUE is The Green Grid's metric (total facility energy ÷ IT equipment energy), later published as ISO/IEC 30134-2. The LBNL summary of the Green Grid PUE paper covers how to measure it.
Worked example
A 1,000 kW IT load at a PUE of 1.40 draws 1,400 kW at the meter, so 400 kW goes to cooling, power conversion and lighting. Over a year that is 1,400 × 8,760 ÷ 1,000 = 12,264 MWh. At $70/MWh the bill is about $858,480, and $245,280 of it pays for the overhead.
Limits
It assumes the IT load and PUE stay flat all year. Real PUE rises in hot weather and at low utilization, and real power prices include demand charges and time-of-use rates.
Common Questions
What is PUE?
Power usage effectiveness: total facility energy divided by IT equipment energy. A PUE of 1.5 means half a watt of overhead for every watt the servers use.
Is a lower PUE always better?
Usually, but some low-PUE designs use more water, and PUE says nothing about how efficiently the servers do useful work.
What price should I enter?
Your all-in delivered price per MWh. For on-site gas power, use your estimated cost of generation, including fuel, maintenance and capital recovery.