PSU Wattage Calculator — Power Supply Estimator
Estimate your PC build’s power draw by component tier (CPU, GPU, drives, fans) and get a recommended PSU size with healthy headroom for GPU spikes.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Breakdown
Estimates use typical tier wattages plus 50% headroom for efficiency and aging. Modern GPUs draw brief transient spikes well above their rating, which justifies the extra margin — always check your GPU vendor’s PSU recommendation too.
About this tool
Building or upgrading a PC and not sure what power supply to buy? Pick the tier of each component — CPU, graphics card, RAM, drives and fans — and this calculator estimates the system's power draw, applies a 1.5× safety margin, and recommends a standard PSU size such as 550 W, 750 W or 1000 W. It saves you from both underpowering a gaming rig and overspending on capacity you will never use. The estimate is computed entirely in your browser; your build details never leave your device.
Frequently asked questions
Why recommend 1.5 times my estimated power draw?
Three reasons. Modern graphics cards produce transient power spikes that can briefly exceed their rated draw by 2× or more, tripping an undersized PSU's protection. Power supplies are also most efficient at around 50–70% load, so headroom means less heat and quieter fans. Finally, capacitors age and a PSU slowly loses capacity over the years, and the margin leaves room for future upgrades. A 1.5× cushion covers all three at once.
How accurate is this estimate for my exact parts?
It is a generic, tier-based estimate, not a per-model database. Two CPUs in the same class can differ by tens of watts, and the gap between graphics card models is even larger. Treat the result as a solid starting point, then check the PSU wattage your GPU vendor recommends for that specific card — NVIDIA and AMD publish a figure for every model — and follow the higher of the two numbers.
Is my build configuration sent anywhere?
No. The component tiers you select and the wattage estimate are computed entirely in your browser with JavaScript — nothing is uploaded, logged or shared. You can compare as many build variations as you like without creating an account or leaving any trace. When you settle on a wattage, also look at the PSU's efficiency rating (80 PLUS Bronze, Gold and so on), which tells you how little power it wastes as heat.