PC Power Supply Wattage Calculator
Adds up a PC’s parts to size its power supply.
Suggested power supply
— W
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Estimated full load — W
Load on that supply — %
Reading this —
The formula
load = sum of component wattages supply = load × (1 + headroom), rounded up to 50 W
A power supply’s rating is what it can deliver to the parts, not what it draws from the wall.
What to watch out for
The default wattages are placeholders. Replace them with the figures for your parts.
Frequently Asked Questions
What size supply does a 500 W system need?
About 650 W with 30% headroom.
Does a bigger supply use more electricity?
No. The PC draws what it needs. An oversized supply can only be a little less efficient at very low load.