PSU Power calculator 2026
Calculate the exact power supply wattage your PC needs — supports all RTX 50, RX 9000 & Intel Core Ultra 200S builds
Core Components
Memory & Storage
Cooling & Peripherals
Adds ~15% CPU and ~10% GPU power draw
- Minimum 0W
- Recommended 0W
- Optimal 0W
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How to use the PSU power calculator
Choosing the right power supply unit (PSU) is one of the most important decisions in any PC build. An undersized PSU can cause system crashes and damage components; an oversized one wastes money. Our free PSU calculator takes the guesswork out of the process.
- Select your CPU from the dropdown — every processor from Intel 10th Gen to Core Ultra 200S and AMD Ryzen 5000 to 9000 series is listed with accurate TDP values.
- Choose your GPU — including the latest NVIDIA RTX 50 Series and AMD Radeon RX 9000 Series cards with real-world power draw figures.
- Enter your RAM sticks, SSDs, HDDs, fans and any extras like an AIO cooler or RGB controllers. Tick Overclocked System if you run your CPU or GPU beyond stock.
- The calculator instantly shows your estimated total system power draw and three PSU size recommendations: Minimum, Recommended and Optimal.
How many watts does a gaming PC need?
Power requirements vary widely depending on your components:
- Budget gaming PC (e.g. Ryzen 5 + RTX 4060): typically 350–450W peak — a quality 550W PSU is ideal.
- Mid-range gaming PC (e.g. Core i5-14600K + RTX 4070 Super): typically 450–600W — a 750W PSU gives comfortable headroom.
- High-end gaming PC (e.g. Ryzen 9 9950X + RTX 5080): typically 700–900W — a 1000W PSU is the sweet spot.
- Extreme / flagship builds (e.g. Core i9 + RTX 5090): up to 900W+ — a 1200W or 1600W PSU is recommended.
Why headroom matters — the 50–80% rule
PSUs are most electrically efficient when running at 50–80% of their rated capacity. Running a PSU at 95% load generates more heat, accelerates wear and can cause instability. That is why our calculator recommends a PSU 30–60% larger than your estimated peak draw — not just to be safe, but to keep your system running cooler, quieter and more efficiently for years.
GPU transient power spikes — why modern cards need extra headroom
Modern high-end GPUs don’t draw power smoothly. Cards like the RTX 5090, RTX 5080 and RX 9070 XT produce millisecond power spikes far above their rated TDP — a 575W-rated RTX 5090 can transient past 650W. Older or undersized PSUs can interpret these spikes as a fault and shut the system down mid-game. If you’re building around a high-end RTX 40 or 50 series card, choose an ATX 3.0/3.1 certified PSU with a native 12V-2×6 (12VHPWR) connector — these are designed to absorb transients up to twice their rated output.
PSU efficiency ratings explained
Look for an 80 Plus certification when buying a PSU. The rating tells you how efficiently the unit converts mains power to DC power for your components:
- 80+ White / Bronze – entry level; suitable for basic office PCs.
- 80+ Gold – the minimum we recommend for any gaming build. Good balance of price and efficiency.
- 80+ Platinum / Titanium – premium efficiency; worth the extra cost for high-wattage or always-on systems.
Frequently Asked Questions
How many watts does my PC need?
Most gaming PCs need between 550W and 1000W. A mid-range build with an RTX 4070 and a Ryzen 7 typically peaks at around 400–550W, so a 750W PSU is a sensible choice. Use the calculator above to get an accurate figure for your exact components.
What PSU size should I buy?
Choose a PSU that is at least 30% larger than your estimated peak draw. This keeps it in the efficient 50–80% load range and gives headroom for future upgrades. An 80+ Gold or Platinum rating is strongly recommended.
How much power does the RTX 5090 need?
The NVIDIA RTX 5090 has a 575W TDP. For a full system with a powerful CPU, NVIDIA recommends at least a 1000W PSU. A high-end build around this GPU is best served by a 1200W–1600W unit.
Does PSU wattage affect PC performance?
An undersized PSU can cause crashes, reboots and component throttling under full load. An oversized PSU does not waste power at idle — modern PSUs scale their draw with load. Matching the PSU size correctly improves both reliability and energy efficiency.
What are GPU transient power spikes?
Modern high-end graphics cards can briefly draw far more power than their rated TDP for a few milliseconds. These transients can trip the over-current protection on an undersized or older PSU, causing sudden shutdowns. For high-end RTX 40/50 series cards, choose an ATX 3.0/3.1 PSU with a native 12V-2×6 connector and at least 30% wattage headroom.
Is a modular PSU worth it?
Yes — a fully or semi-modular PSU lets you omit unused cables, improving airflow inside the case and making cable management much easier. The performance is identical to non-modular units; you’re paying for tidiness and installation convenience.