Estimated Load: 0 W
Recommended PSU: 0 W
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PSU Calculator Use
Choosing the right Power Supply Unit (PSU) is critical for PC stability and longevity. Use this psu calculator to estimate the total power draw of your computer components and determine the ideal wattage for your power supply. By providing specific thermal design power (TDP) values for your processor and graphics card, you can avoid system crashes and hardware degradation caused by under-powered units.
Whether you are building a budget office workstation or a high-end liquid-cooled gaming rig, understanding your power requirements prevents overspending on unnecessary wattage while ensuring your components receive clean, consistent energy.
- CPU TDP (Watts)
- The Thermal Design Power of your processor, found on the manufacturer's spec sheet (Intel or AMD).
- GPU TDP (Watts)
- The maximum power draw of your graphics card under load. This is usually the largest power consumer in the system.
- Safety Overhead
- A percentage buffer (typically 20%) to account for transient power spikes, capacitor aging, and future peripheral additions.
How It Works
The psu calculator aggregates the peak power consumption of every major component. While a PC rarely uses 100% of its capacity across all components simultaneously, we calculate for the "worst-case scenario" to ensure the system never loses power during intense tasks like 4K gaming or video rendering.
Total Wattage = [(CPU + GPU + Storage + RAM/Mobo) × Load Profile] × (1 + Safety Margin)
- Storage Power: Modern SSDs use ~3-5W, while traditional 7200RPM HDDs can draw up to 10W during spin-up.
- Motherboard/RAM: A standard motherboard and 2-4 sticks of RAM typically account for 50W to 80W.
- Efficiency: PSUs are most efficient at 50% load; our calculation aims for a PSU size that keeps you in the high-efficiency curve.
Calculation Example
Example: A mid-range gaming PC featuring an Intel i5-13600K and an NVIDIA RTX 3070.
Step-by-step solution:
- CPU TDP: 125W
- GPU TDP: 220W
- Storage: 2 SSDs (2 × 8W = 16W)
- Misc (Mobo/Fans/RAM): 60W
- Base Total: 125 + 220 + 16 + 60 = 421W
- Apply 20% Safety Margin: 421 × 1.20 = 505.2W
- Result: A 550W or 600W PSU is recommended.
Common Questions
What is 80 Plus Rating?
The 80 Plus certification indicates how efficiently the PSU converts AC power from the wall into DC power for your PC. Ratings include White, Bronze, Silver, Gold, Platinum, and Titanium. A higher rating means less energy is wasted as heat, which can lower your electricity bill and keep your system cooler.
Can I use a PSU with too much wattage?
Yes. Your components will only draw the amount of power they need. Having an 850W PSU in a system that only needs 400W will not harm anything; in fact, it often results in the PSU fan staying off because the load is so low relative to its capacity.
What are transient spikes?
Modern GPUs can have "transient spikes"—millisecond bursts where power consumption doubles or triples its rated TDP. This is why our psu calculator includes a safety margin. Without this buffer, these spikes can trigger the PSU's Over Current Protection (OCP) and cause the PC to shut down instantly during gaming.