What PSU size do I need for a gaming PC?

Most gaming PCs need a PSU between 550W and 850W . A mid-range build with a card like an RTX 4070 usually needs around 650W. High-end builds with an RTX 4090 or RX 7900 XTX often need 850W or more. Use the calculator above to get an exact number for your specific parts.

Can a PSU that is too powerful damage my PC?

No. A PSU only delivers the watts your parts actually need. If you buy a 1000W PSU but your PC only draws 400W, the PSU just runs at a low load. It will not force extra power into your components. The only downside is spending more money than you needed to.

What happens if my PSU is too weak?

Your PC may crash, restart randomly, or refuse to turn on. Under heavy load, a weak PSU can cause blue screens, data loss, or even damage your motherboard and other parts. Always pick a PSU that meets or exceeds your calculated wattage.

What does the safety headroom setting do?

Safety headroom adds extra wattage on top of your total power draw. For example, if your parts use 500W and you set 30% headroom, the calculator recommends at least 650W. This keeps your PSU from running at full load, which makes it last longer, run cooler, and stay quieter.

What headroom percentage should I choose?

30% is the best choice for most builds. Use 20% if you are on a tight budget and do not plan to upgrade. Use 40% or 50% if you overclock heavily or want room to add a stronger GPU later.

What is an 80 Plus rating?

80 Plus is an efficiency rating for power supplies. It tells you how well the PSU converts wall power into usable power for your PC. The main tiers are Bronze, Gold, Platinum, and Titanium . A Gold-rated PSU wastes less electricity as heat than a Bronze one, saving you money on your electric bill.

Which 80 Plus rating should I get?

80+ Gold is the sweet spot for most people. It offers high efficiency without a huge price jump. For PSUs over 1000W, Platinum or Titanium is worth considering because the energy savings add up at higher wattages.

Does the calculator include power spikes?

The calculator uses each component's rated TDP, which is its typical maximum power draw. Short power spikes, especially from modern GPUs, can go above TDP for a fraction of a second. The safety headroom setting helps cover these spikes. For builds with high-end GPUs like the RTX 4090, use at least 30% headroom.

How much power does a GPU use compared to a CPU?

In most gaming PCs, the GPU uses the most power. A high-end GPU like the RTX 4090 draws 450W, while a typical gaming CPU draws 105W to 170W. The power breakdown chart in the results section shows you exactly how much each part uses in your build.

Do I need a bigger PSU for two GPUs?

Yes. Two GPUs can nearly double your graphics card power draw. For example, two RTX 3080 cards draw about 640W just from GPUs alone. If you run a dual-GPU setup, expect to need a PSU of 1000W or higher. The calculator handles this automatically when you select the 2x GPU option.

How much power do RAM sticks use?

RAM uses very little power. A single DDR5 16GB stick draws about 4.8 watts , and a DDR4 16GB stick draws about 3 watts. Even with four sticks, RAM adds less than 20W to your total. It is one of the smallest power consumers in any build.

Does RGB lighting affect PSU size?

A little. Light RGB adds about 5W, while heavy RGB setups with multiple strips and fans can add up to 30W. It usually does not change which PSU size you need, but the calculator includes it for an accurate total.

How is the monthly electricity cost calculated?

The calculator estimates cost by assuming your PC runs at full load for 4 hours per day at $0.16 per kWh for 30 days . The formula is: (total watts ÷ 1000) × 4 hours × 30 days × $0.16. Your actual cost will vary based on your electricity rate and how many hours you use your PC.

What PSU wattage sizes are available?

PSUs come in standard sizes. Common options are 350W, 400W, 450W, 500W, 550W, 600W, 650W, 700W, 750W, 800W, 850W, 1000W, 1200W, 1300W, 1500W, and 1600W . The calculator rounds your result up to the nearest standard size so you can shop easily.

Should I buy a modular or non-modular PSU?

A modular PSU lets you remove cables you do not need, which makes cable management easier and improves airflow. A non-modular PSU has all cables permanently attached and costs less. For most builds, a semi-modular or fully modular PSU is worth the small extra cost.

Can I use this calculator for a workstation or server?

Yes. The calculator works for any desktop PC, including workstations. Pick your CPU, GPU, storage drives, and cooling setup just like you would for a gaming build. For servers with many hard drives, increase the HDD count and use 40% or 50% headroom for reliability.

What does TDP mean for CPUs and GPUs?

TDP stands for Thermal Design Power. It is the maximum amount of heat (in watts) a chip produces under normal heavy use. PSU calculators use TDP as a close estimate of how much electrical power each component draws. Actual power draw may be slightly higher or lower.

Why does the calculator show a higher wattage than my parts add up to?

The recommended wattage includes your safety headroom buffer. If your parts total 500W and you have 30% headroom, the calculator suggests about 650W. This extra room protects against power spikes, keeps your PSU efficient, and gives you space for future upgrades.

PSU Calculator - CPU, GPU, Storage, Cooling & Safety Headroom

Component	Detail	Watts
Total System Load	0W

Introduction

A power supply unit (PSU) is one of the most important parts of any PC build. If your PSU is too weak, your computer can crash, shut down, or even damage your parts. If it is too strong, you waste money. Our PSU calculator helps you find the right wattage for your exact build in just a few clicks.

Start by picking your CPU brand and model. Then choose your graphics card, RAM, storage drives, fans, and cooling setup. The calculator adds up the power draw from every part and includes a safety buffer so your PSU never runs at full load. You get a clear wattage recommendation, a power breakdown chart, and a cost estimate for electricity. If you want to understand the underlying electrical relationships, our Ohm's Law calculator and power calculator can help you explore how voltage, current, and wattage relate to each other.

This tool works for all types of builds — from budget office PCs to high-end gaming rigs with multiple GPUs. It covers Intel and AMD processors, NVIDIA and AMD graphics cards, and Intel Arc GPUs. Whether you are building your first computer or upgrading an old one, this calculator tells you exactly what PSU size you need.

How to Use Our PSU Calculator

Enter your PC parts below to find out how many watts your power supply needs. The calculator adds up the power draw of each part and tells you the right PSU size for your build.

CPU Brand: Pick Intel or AMD. This unlocks the rest of the calculator.

Socket Type: Choose the CPU socket that matches your motherboard.

CPU Model: Select your specific processor from the list. Each one shows its power draw in watts.

CPU Overclocking: Pick None if your CPU runs at stock speeds. Pick OC for light overclocking or Heavy for extreme overclocking.

Motherboard Form Factor: Choose the size of your motherboard, such as ATX or Mini-ITX. Bigger boards use more power.

GPU Configuration: Choose whether you have one or two graphics cards in your system.

GPU Manufacturer: Pick NVIDIA, AMD, or Intel for each graphics card slot.

GPU Model: Select your exact graphics card. Each one shows its TDP in watts.

GPU Overclocking: Set the overclock level for each GPU, just like the CPU option.

RAM Module: Choose your RAM type and size, such as DDR5 16GB or DDR4 8GB. If you are setting up a Minecraft server, getting the right amount of RAM is just as important as the power supply behind it.

RAM Sticks: Enter how many RAM sticks are installed in your PC.

SSD / NVMe Drives: Enter the number of solid state drives in your build. Each one uses about 6 watts.

HDD Drives: Enter the number of hard disk drives. Each one uses about 9 watts.

Case/CPU Fans: Enter the total number of fans in your case. Each fan uses about 3 watts.

CPU Cooler: Pick your cooler type. Stock air coolers add no extra watts. Liquid coolers and custom loops add 15 to 25 watts.

RGB / Lighting: Choose how much RGB lighting your build has, from none to heavy.

Safety Headroom: This adds extra wattage so your PSU is never maxed out. A 30% buffer is a good starting point for most builds.

Click Calculate to see your recommended PSU wattage, a power breakdown chart, and a full parts table. Click Reset to clear all fields and start over.

What Is a PSU Calculator?

A PSU calculator helps you figure out how much power your computer needs. PSU stands for Power Supply Unit. It is the part inside your PC that sends electricity to every component, like your CPU, graphics card, RAM, and storage drives. If your PSU is too weak, your computer can crash, shut down, or not turn on at all. If it is too strong, you just spend extra money you did not need to. For a broader look at power generation and sizing, you may also find our generator sizing calculator useful.

Why PSU Wattage Matters

Every part in your computer uses a certain amount of power, measured in watts. A basic office PC might only need 300 watts, while a high-end gaming PC with a powerful graphics card could need 850 watts or more. When you add up the watts from every component, you get your total system load. Your power supply should always be rated higher than that total. Most experts suggest adding 20% to 30% extra headroom so your PSU is never running at full capacity. This keeps it cooler, quieter, and longer-lasting. You can use our percentage calculator to quickly figure out any headroom percentage on a given wattage.

How to Pick the Right Power Supply

Start by knowing your two biggest power draws: the CPU and the GPU. These two parts alone often use more than half of your total power. After that, add in your motherboard, RAM sticks, hard drives, SSDs, fans, and any RGB lighting. Once you have the total, round up to the nearest standard PSU size, like 550W, 650W, 750W, or 850W. You should also look for a PSU with an 80 Plus rating. This rating tells you how efficiently the PSU converts wall power into usable power. Common ratings are 80+ Bronze, Gold, and Platinum. Higher ratings waste less electricity as heat, which saves you money on your electric bill over time. To estimate what that electricity costs, try our electricity cost calculator. If you want to convert between watts and amps to check your wall outlet capacity, our watts to amps calculator and amps to watts calculator make that easy.

Overclocking and Power Draw

Overclocking means pushing your CPU or GPU to run faster than its default speed. This gives you better performance, but it also uses more electricity. A heavily overclocked chip can draw 25 watts or more above its normal rating. If you plan to overclock, always pick a PSU with extra headroom to handle those power spikes safely. Understanding the relationship between voltage, current, and resistance is key to safe overclocking — our voltage divider calculator and voltage drop calculator can help you explore those electrical fundamentals. For builders concerned about the total cost of a new rig, tools like our ROI calculator can help you weigh the investment.

PSU Calculator