PC Power Supply Calculator
Enter your parts below to estimate system draw and get a recommended PSU wattage with safety headroom.
Tip: If your GPU has very high transient spikes, choose at least 40% headroom and consider an ATX 3.0/3.1 PSU.
How to choose the right PC power supply
A power supply unit (PSU) is one of the most important parts in any build. If it is too small, your system can crash under load or fail to boot. If it is massively oversized, you may spend more than necessary without seeing real benefit. A good PSU size balances stability, upgrade room, and cost.
What this calculator estimates
This calculator adds together major component power draw: CPU, GPU, motherboard, memory, drives, cooling, and accessories. Then it applies a safety margin (headroom) and rounds up to a common PSU wattage tier.
- Estimated component draw: Approximate DC power required by your parts.
- Recommended PSU: Includes your selected headroom percentage.
- Estimated wall draw: Accounts for PSU efficiency level (Bronze, Gold, etc.).
Why headroom matters
Modern CPUs and especially GPUs can spike above their stated sustained power. Headroom helps absorb those short bursts and keeps your PSU from running at its limit all day.
- 20% headroom: Lean sizing for efficient mid-range builds.
- 30% headroom: Great default for most gaming and workstation PCs.
- 40%+ headroom: Better for high-end GPUs, overclocking, or future upgrades.
Quick sizing examples
Entry gaming build
CPU 65W + GPU 160W + typical extras can land around 300W real draw. With 30% headroom, a quality 450W to 550W PSU is usually perfect.
Mainstream gaming build
CPU 125W + GPU 250W + common accessories often lands around 480W. With 30% headroom, a 650W PSU is a strong target, while 750W adds upgrade room.
High-end creator or enthusiast build
CPU 200W + GPU 450W + storage, pumps, and fans can reach 800W+ in heavy mixed loads. In this case, 1000W to 1200W with strong transient handling is recommended.
80 PLUS ratings and efficiency
Efficiency does not increase your component performance, but it does reduce wasted power and heat. Higher-rated PSUs can run cooler and quieter under similar load.
- Bronze: cost-effective and acceptable for many builds
- Gold: best price/performance for most users
- Platinum/Titanium: premium efficiency for heavy usage or silence-focused systems
ATX 3.0 / ATX 3.1 and GPU spikes
If you are buying a modern high-power graphics card, prioritize an ATX 3.0 or ATX 3.1 PSU with native PCIe 5.x power support. These designs are built to tolerate fast transient spikes that older units may struggle with.
PSU buying checklist
- Choose wattage from real system load + headroom, not guesswork.
- Buy from a reputable brand and platform with good electrical protections.
- Check cable support (EPS, PCIe 8-pin, 12V-2x6/12VHPWR, SATA count).
- Look for a long warranty and independent reviews.
- Prefer fully modular units for easier cable management.
Final recommendation
For most users, a high-quality 650W to 850W 80 PLUS Gold PSU is the sweet spot. Use the calculator above to get a personalized number, then round up to a trusted model with the connectors your build needs today and room for tomorrow.