🔌 PC Power Supply (PSU) Wattage Calculator
Pick your components and get an estimated total load plus a recommended power-supply wattage — sized with headroom so your PC runs stable, efficient, and ready for an upgrade.
🔌 Recommended power supply
Sizing for ~30% headroom keeps the PSU near its efficient ~50% load point and leaves room for boost and future upgrades. Choose an 80 PLUS Bronze/Gold unit from a reputable brand — quality matters more than raw wattage. These are general estimates; check each component's real spec.
📊 Load breakdown
| Component | Watts |
|---|---|
| Motherboard + base | 50 W |
| CPU | 105 W |
| GPU | 220 W |
| RAM (2 × 3 W) | 6 W |
| HDDs (1 × 7 W) | 7 W |
| SSDs (1 × 3 W) | 3 W |
| Fans (4 × 3 W) | 12 W |
| Total load | 403 W |
Size the PSU with confidence
An undersized power supply causes crashes, shutdowns under load, and premature failure; a wildly oversized one wastes money and runs less efficiently. The sweet spot is a quality unit rated a comfortable margin above your real draw. Add up the components here and you have a target wattage to shop against.
The two components that dominate the total are the CPU and the graphics card — look up their TDP on the manufacturer's page for the most accurate result, then let the calculator add the rest of the system.
❓ Frequently Asked Questions
How does the PSU wattage calculator work?
It sums the estimated draw of each component — a ~50 W motherboard base, plus your CPU TDP, GPU TDP, RAM sticks at ~3 W each, hard drives at ~7 W, SSDs at ~3 W, and fans at ~3 W — to get your total load. It then multiplies by about 1.3 for headroom and rounds up to the nearest common retail size (450, 550, 650, 750, 850, or 1000 W).
Why recommend a PSU bigger than my actual load?
Two reasons. Power supplies are most efficient at roughly 40–60% load, so a unit sized well above your draw runs cooler and quieter. And headroom leaves room for CPU/GPU boost spikes and future upgrades. Sizing for about 30% above measured load is a common, practical rule of thumb.
What does 80 PLUS mean, and does the brand matter?
80 PLUS (Bronze, Gold, Platinum…) certifies how efficiently a PSU converts wall power to DC — higher tiers waste less as heat. Just as important is build quality: a reputable brand with good protections is worth more than raw wattage. A quality 650 W unit beats a no-name 850 W one.
How accurate is this estimate?
It is a solid starting point, not a spec sheet. These are general estimates using typical component wattages — your exact CPU and GPU TDPs, overclocking, and the number of drives and fans all shift the real figure. Check each part's rated power and, for high-end builds, the GPU maker's recommended PSU.