PSU Calculator: Power Supply Wattage Tool
Select your CPU, GPU, RAM, storage, and a few build details to get a recommended power supply wattage with proper headroom built in — not just a bare-minimum number that leaves no margin for spikes or future upgrades.
| Component | Estimated Draw |
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How PSU Sizing Actually Works
A power supply calculator isn't just adding up rated wattages. Modern GPUs, especially RTX 40- and 50-series and RX 8000-series cards, draw brief power spikes well above their rated TDP — sometimes 1.5 to 2x for a few milliseconds. A PSU sized exactly to your components' rated draw can trip or shut down under these spikes even though your average power use is well within spec. That's why this calculator adds roughly 30% headroom on top of the raw component total, rather than recommending the bare minimum.
Why Efficiency Rating Matters
An 80+ Bronze, Gold, or Platinum rating tells you how much of the power your PSU draws from the wall is actually delivered to your components versus lost as heat. A cheap, unrated or poorly-rated PSU running near its limit is a real reliability risk — the kind that takes other components down with it if it fails. We'd rather you spend a bit more on a properly rated unit than save $20 on something that risks the rest of your build.
Common PSU Sizing Mistakes
- Sizing to bare minimum. Running a PSU consistently near 90-100% of its rated capacity shortens its lifespan and increases the risk of instability under load spikes.
- Ignoring the 12VHPWR / 12V-2x6 connector requirement. If you're running an RTX 40 or 50-series card, or newer AMD flagship, check whether your PSU has native support for this connector rather than relying on an adapter.
- Forgetting future upgrades. If you're planning a GPU upgrade in a year or two, size your PSU for that future card, not just your current one.
- Buying an unbranded or unrated unit to save money. The PSU is one of the few components that can damage everything else in your system if it fails poorly. This isn't the place to cut corners.
What This Calculator Doesn't Account For
- Peripherals beyond basic fans (large watercooling pumps, extensive RGB, multiple monitors powered through USB-C)
- Multiple GPUs (SLI/CrossFire setups, now rare, need substantially more headroom)
- Extreme overclocking beyond a moderate margin
- Regional voltage and efficiency curve differences
Frequently Asked Questions
Why does this recommend more wattage than my components' rated power adds up to?
Modern GPUs spike well above their rated TDP for brief moments, and a PSU running consistently near its limit degrades faster and is more prone to instability. The 30% headroom accounts for both.
Is a higher wattage PSU always better?
Not necessarily. PSUs are most efficient in the 40-60% load range, so wildly oversizing wastes money and can slightly reduce efficiency at low loads. Match your PSU to your actual build, not the largest number you can afford.
Do I need 80+ Gold, or is Bronze fine?
Bronze is the practical minimum for a reliable build today. Gold pays for itself over time through lower electricity cost and typically better overall build quality, and is worth the modest price difference for anything mid-range or above.
What is ATX 3.0/3.1 and do I need it?
ATX 3.0/3.1 PSUs are designed with native support for modern GPU transient spikes and the 12VHPWR/12V-2x6 connector. If you're running a current-generation NVIDIA or AMD flagship GPU, an ATX 3.0/3.1 unit is worth prioritizing over an older-spec PSU of the same wattage.
Can I use an adapter instead of a native 12VHPWR connector?
You can, but native support is safer and reduces the risk of connector issues that have been reported with adapters on high-power cards.
Should I check my system for a bottleneck too?
Sizing your PSU correctly and getting a balanced CPU/GPU pairing are separate problems — run your components through our bottleneck calculator to check for a performance mismatch alongside your power planning.
