PSU Wattage Calculator
Estimate total PC component wattage from CPU and GPU TDP, RAM, storage, and fans. Get PSU capacity recommendation with headroom and electricity cost per hour.
Loading tool...
What is PSU Wattage Calculator?
The PSU Wattage Calculator estimates your PC build's total power draw from CPU and GPU TDP, RAM, storage, and case fans. It recommends a PSU capacity with 30% headroom above peak, and estimates electricity cost per hour based on your local rate.
Key Benefits
- Prevent underpowered builds that crash under load
- 30% headroom for transient spikes and longevity
- Electricity cost estimate for long-term budgeting
- Overclock toggle for high-performance builds
Common Use Cases
- •Planning a new PC build and choosing the right PSU
- •Checking whether your current PSU can handle a GPU upgrade
- •Estimating electricity costs for a gaming or workstation PC
- •Comparing power draw across different CPU and GPU combinations
- •Verifying that an overclocked build has enough headroom
Calculate Your PSU Wattage
- Enter CPU and GPU TDP: Look up the TDP (thermal design power) of your CPU and GPU - these are the two biggest power consumers.
- Add peripherals: Enter the number of RAM sticks, storage drives, and case fans - each contributes a small amount.
- Toggle overclocking: If you plan to overclock, enable the toggle to add a 30% peak headroom buffer.
- Read the recommendation: The recommended PSU capacity includes 30% headroom above peak draw for efficiency and longevity.
Key Features
- CPU and GPU TDP as the primary power draw inputs
- RAM, storage, and fan power contributions included
- Overclock toggle adds a 30% peak headroom buffer
- PSU recommendation rounded up to the nearest 50W
- Electricity cost per hour based on your local rate
- Instant client-side results - no account needed
Frequently Asked Questions
How is PSU wattage calculated?
The tool sums the TDP of your CPU and GPU, adds per-component estimates for RAM (5W each), storage drives (8W each), and case fans (3W each), then applies a 15% load factor (30% with overclocking) for transient spikes. It recommends a PSU capacity with 30% headroom above peak, rounded up to the nearest 50W.
Why does my PSU need more capacity than my peak draw?
PSUs are most efficient at 50-70% load (the "sweet spot"). Running at 90%+ reduces efficiency, increases heat, and shortens lifespan. A 30% headroom also handles transient power spikes from modern GPUs.
Does TDP equal actual power draw?
Not exactly. TDP is a thermal design guideline, not the maximum electrical draw. Modern CPUs and GPUs can briefly exceed TDP during boost. The headroom in the calculation accounts for this.
What electricity rate should I enter?
Enter your local rate in dollars per kilowatt-hour. The tool estimates cost assuming 60% average load. Check your utility bill for the exact rate - the US average is around $0.15/kWh.