Free calculator · also available as an API

How big a power supply does this build actually need?

Adding up TDP numbers undersizes builds. Intel's TDP is base power, not peak, and modern GPUs spike far above their rated draw for microseconds at a time. This calculator models both, and shows you its reasoning.

Why this differs from other calculators

Intel TDP is not peak draw

An i9-14900K is rated at 125 W and pulls up to 253 W under PL2. Treating the rating as the ceiling underestimates the CPU by half.

GPUs spike above their board power

Ampere and Ada cards draw close to double their rated power for sub-millisecond windows. This is why quality units tripped their over-current protection with RTX 3080s.

Laptop parts never contaminate desktop maths

A GTX 1080 Max-Q draws 150 W; the desktop GTX 1080 draws 180 W. They share a name in most datasets. Here they are separate records.

No invented performance scores

You will not find a bottleneck percentage here. That number requires benchmark data, which this dataset does not contain, so publishing one would mean making it up.

Use it from your own code

Same engine, same data, as a JSON API — for build planners, retail configurators, or anything that needs to size a supply programmatically.

curl "https://api.jerebrunen.com/v1/psu?cpu=Ryzen%207%207800X3D&gpu=RTX%204090"

Interactive documentation · OpenAPI specification