PSU Wattage Calculator
Pick your processor and graphics card for an estimated draw and the wattage to actually buy — including the minimum the card's own manufacturer specifies, which is often the higher of the two.
2
4W each1
6W eachChoose a processor to get a wattage figure. Everything else is optional.
Common questions
- How many watts does my PC need?
- Add up what each part draws under load, then buy a supply about 25% above that. The processor and graphics card account for most of it; a motherboard, memory, drives and fans together rarely exceed 60W. A typical mid-range gaming build lands between 450W and 650W.
- Why does my graphics card ask for more watts than my build draws?
- Because the manufacturer's figure is not a sum of steady-state draw. Cards pull large spikes for a few milliseconds at a time, and a supply that cannot deliver them shuts down under load even though the average is well within its rating. NVIDIA specifies a 550W supply for an RTX 3050 that draws 130W for exactly this reason. When a card's minimum is higher than the calculated recommendation, buy against the card's number.
- Is a bigger power supply always better?
- No. Supplies are least efficient at the very bottom of their range, so a 1000W unit running a 200W machine wastes energy and money. Headroom of roughly 25 to 40% above real draw is the useful band — enough for spikes and a future upgrade, not so much that you paid for capacity you will never use.
- Does the efficiency rating change how many watts I need?
- Not the wattage, no. An 80 Plus Gold unit and a Bronze unit of the same rating both deliver the same power to the machine; Gold simply wastes less as heat drawing it from the wall. Efficiency affects your electricity bill and how hot and loud the supply runs, not the size you need to buy.
The rest of the build
Wattage is one of several things worth getting right before you buy. The full builder runs this same calculation as you pick, and adds socket and chipset matching, memory type and slot counts, and graphics card and cooler clearance against your case.