PUE, power usage effectiveness, compares the overhead power a data center uses with the power its computers use.
By Tony Yu / tkal · November 2, 2026 · One-minute visual guide
Same building. Two kinds of power.
Power into the building ♡
↓
Computingthe IT gear doing the work
vs
Overheadcooling and power distribution
PUE compares the two. Lower means less overhead.
An illustration, not a measured split. Each building’s mix is different.
Keep this bitPUE is a ratio that compares a data center’s non-computing overhead energy with the energy its computers use.
Why care?
A PUE of 2.0 means that for every watt of IT power, another watt goes to cooling and power distribution. Google says its fleet averaged 1.09 in 2025; the Uptime survey average was 1.54.
The catch
It grades the building, not the chips. Make the computers more efficient and PUE can actually rise.
Computing
Overhead