TweakGearPro

Power Supply Calculator

Tally your whole-system wattage and get a recommended PSU size with safe headroom.

No signupNo paywallInstant resultsRuns in your browser
CPU150 W
GPU220 W
Motherboard30 W
RAM (2×)16 W
Storage (1×)8 W
Fans (4)30 W
USB (2)20 W
System Peak474 W
Recommended PSU (35% headroom)
650 W
550–650W 80+ Gold

Headroom covers transient spikes (GPU boost, USB surges, capacitor aging). Always cross-check the GPU vendor's stated PSU minimum.

How this calculator works

Each component is assigned a realistic loaded wattage (CPU and GPU scale by tier, RAM/SSD/fans are counted per device). The overclocking option bumps CPU and GPU draw by 10–24% to reflect boost + voltage headroom. The recommended PSU is the system peak multiplied by 1.35 (35% headroom), rounded up to the next common wattage step. Headroom matters because GPU boost transients and aging capacitors push real peaks above steady-state draw.

When to use it

Run this before buying a PSU, adding a second GPU, or upgrading to a power-hungry flagship card. Undersizing causes random reboots under load; massive oversizing wastes money and efficiency. Cross-check the result against the GPU vendor's stated PSU minimum, which you'll find on every spec page.

Frequently Asked Questions

Why 35% headroom and not 20%?▾
Modern GPUs spike well above their average draw for milliseconds. A 35% buffer keeps you inside the PSU's efficient 50–80% load band and leaves room for future upgrades and capacitor aging.
Should I buy an 80+ Gold or Platinum unit?▾
Gold is the sweet spot for most builds. Platinum pays back only if your PC runs near-idle many hours a day. Never go below Bronze for a gaming rig.
My GPU says it needs a 750W PSU but this tool says 650W. Who's right?▾
Vendor minimums include safety margin for worst-case PSUs. If both numbers agree within a tier, pick the higher one for peace of mind.
Do case fans really matter?▾
Each fan is ~3–5W, so a full fan rig is minor — but RGB controllers, AIO pumps and USB hubs add up. The calculator counts them so your total is honest.

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