PC Power Supply Calculator
Enter your CPU and GPU TDP, add motherboard, RAM, drives and fans to estimate total system power draw. Get a recommended PSU wattage with a safety margin. Runs locally.
Updated July 11, 2026
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PC Components
Safety Margin
Estimated Draw
355W
Sum of all components
Recommended PSU
497W
With 1.4x safety margin
PSU Tier
550W
Nearest standard wattage
Power Breakdown
Standard PSU Wattage Tiers
How to use
- 1
Enter CPU and GPU TDP values.
- 2
Add other component power draws.
- 3
See total draw and recommended PSU wattage.
How it works
TDP is a heat rating, not a power meter
TDP (Thermal Design Power) is the maximum heat a cooling system must dissipate to keep a chip within spec โ it approximates sustained power consumption under realistic load but is not a hard ceiling. Modern GPUs routinely draw transient spikes 1.5โ2ร their rated TDP for milliseconds, which can trip over-current protection on an undersized PSU.
That is why the calculator applies a 1.3โ1.5ร headroom multiplier: to absorb those spikes, leave room for fan and peripheral power, and let the PSU operate near its most efficient midpoint (around 50% load).
Efficiency tiers explained
A PSU rated 80% efficient delivering 400 W to your components actually pulls 400 รท 0.80 = 500 W from the wall โ the missing 100 W leaves as heat. Higher efficiency tiers waste less and run cooler and quieter.
| Tier | 20% load | 50% load | 100% load |
|---|---|---|---|
| 80 PLUS (White) | 80% | 80% | 80% |
| Bronze | 82% | 85% | 82% |
| Silver | 85% | 88% | 85% |
| Gold | 87% | 90% | 87% |
| Platinum | 90% | 92% | 89% |
| Titanium | 92% | 94% | 90% |
Efficiency also varies with load โ every tier peaks around 50% load and dips at idle. A 1000 W Gold PSU running a 200 W idle system is no more efficient than a 450 W Bronze.
How this is calculated
- Formula:
- Recommended PSU wattage = (ฮฃ component TDP + overhead) ร safety multiplier (1.3โ1.5). Wall power drawn = system power รท PSU efficiency (e.g. at 80% efficiency, 400 W delivered draws 500 W from the wall).
- Applies to:
- Generic TDP-based estimate; actual peak draw varies by silicon, clocks, voltage, and load.
Component TDP (thermal design power) is a cooling specification, not a precise power-consumption figure โ real-world peak draw can differ substantially, especially under transient spikes from modern GPUs. This tool provides sizing guidance only, not a guarantee. Always verify with the manufacturer's official specifications and power-supply recommendations before purchase.