PC Power Supply Calculator
Estimate your PC peak power consumption and find the recommended power supply (PSU) wattage for your build.
Real-time Results
Suggested power supply wattage
Estimated absolute maximum draw
Power Draw Breakdown
Estimated power consumption per component
| Item | Value |
|---|---|
| Processor (CPU) Based on provided TDP | 65 W |
| Graphics Card (GPU) Based on provided TGP | 200 W |
| Motherboard & USB Estimated average baseline | 50 W |
| RAM, Storage, Fans Combined minor components | 38 W |
| Safety Margin (20%) Headroom for transient spikes | +71 W |
Why Choose PC Power Supply Calculator
Building a custom PC requires ensuring that your Power Supply Unit (PSU) can handle the peak power draw of your components. The PC Power Supply Calculator takes your CPU, GPU, RAM, storage, and cooling setup into account to estimate your total system wattage. It then applies a safety margin to recommend the ideal PSU wattage, preventing system crashes caused by transient power spikes.
- ✓Estimates absolute peak power draw based on component TDPs
- ✓Accounts for minor components like RAM, SSDs, HDDs, and fans
- ✓Applies a customizable safety margin to ensure long-term stability
- ✓Recommends a standard, commercially available PSU wattage rating
How to Calculate
- 1Input the TDP (Thermal Design Power) of your CPU.
- 2Input the TDP/TGP of your graphics card.
- 3Enter the number of RAM sticks, storage drives, and cooling fans.
- 4Set a safety margin (20% to 30% is highly recommended).
- 5Review your estimated peak power and the recommended PSU wattage.
Frequently Asked Questions (FAQ)
Why do I need a safety margin?
Modern high-end graphics cards can experience 'transient power spikes' that last milliseconds but draw double their rated power. A safety margin ensures your PSU doesn't trip its over-current protection and shut down your PC. Additionally, PSUs operate most efficiently at 50% to 70% load.
What happens if my PSU wattage is too low?
If your components draw more power than the PSU can provide, your PC will likely hard crash or shut off randomly during heavy workloads like gaming or video rendering.
Does having a higher wattage PSU use more electricity?
No. Your PC only draws the power it needs from the PSU. An 850W PSU running a 400W system will still only pull roughly 400W from the wall (plus a small amount lost as heat).
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