Power Supply Calculator

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Power Supply Calculator
Desktop / Home OfficeGaming PC (High Performance)Workstation / Server
Result:
Enter values to see result
function calculatePsu(){var cpu=parseFloat(document.getElementById('cpu_tdp').value);var gpu=parseFloat(document.getElementById('gpu_tdp').value);var other=parseFloat(document.getElementById('other_parts').value);var margin=parseFloat(document.getElementById('headroom').value);if(isNaN(cpu)||isNaN(gpu)||isNaN(other)||isNaN(margin)){alert('Please enter valid numeric values for all fields');return;}var rawTotal=cpu+gpu+other;var marginWatts=rawTotal*(margin/100);var finalTotal=rawTotal+marginWatts;var recommended=Math.ceil(finalTotal/50)*50;if(recommended<finalTotal){recommended+=50;}document.getElementById('summaryResult').innerHTML='Recommended PSU: '+recommended+' Watts';if(document.getElementById('show_steps').checked){var steps='
Total Component Draw: '+rawTotal.toFixed(0)+'W
Safety Margin ('+margin+'%): '+marginWatts.toFixed(0)+'W
Estimated Max Load: '+finalTotal.toFixed(0)+'W';document.getElementById('breakdown').innerHTML=steps;document.getElementById('breakdown').style.display='block';}else{document.getElementById('breakdown').style.display='none';}}

Using the Power Supply Calculator

Building a custom PC requires a careful balance of power delivery. Our power supply calculator helps you estimate the total wattage your system will consume under peak load. By entering the Thermal Design Power (TDP) of your main components, you can ensure your Power Supply Unit (PSU) has enough capacity to maintain stability and prevent sudden shutdowns during gaming or heavy workloads.

Selecting the right PSU is not just about meeting the minimum requirements; it is about efficiency and longevity. A power supply that runs at 50% to 80% load is generally more efficient and quieter than one pushed to its absolute limit.

CPU TDP (Watts)
The Thermal Design Power of your processor. High-end CPUs like Intel Core i9 or AMD Ryzen 9 typically range from 105W to 250W.
GPU TDP (Watts)
The power draw of your Graphics Card. This is usually the most power-hungry component in a gaming rig, often requiring 200W to 450W.
Other Parts
Includes Motherboard (approx. 30W-80W), RAM (3W per stick), SSDs/HDDs, and cooling fans or RGB strips.
Safety Margin / Headroom
A buffer (typically 20%) to account for transient power spikes, future upgrades, and component aging.

How It Works: The Calculation Formula

The power supply calculator uses a simple but effective logic to determine your needs. It aggregates the peak power draw of all components and then applies a safety multiplier to handle spikes.

Recommended PSU = (Total Component Watts × (1 + Margin Percentage)) Rounded Up to Nearest 50W

  • Base Load: The sum of CPU, GPU, and peripheral wattage.
  • Transient Spikes: Modern GPUs can momentarily draw significantly more power than their rated TDP; the headroom factor accounts for this.
  • Efficiency Curve: Most PSUs are most efficient at roughly 50% load. A higher wattage PSU may actually save electricity over time.

Calculation Example

Example: A mid-range gaming PC with an Intel i5-13600K and an NVIDIA RTX 4070.

Step-by-step solution:

  1. CPU TDP = 125W
  2. GPU TDP = 200W
  3. Other Parts (RAM, Fans, NVMe) = 60W
  4. Base Total = 125 + 200 + 60 = 385W
  5. Apply 20% Headroom = 385 * 1.20 = 462W
  6. Recommended PSU = 500 Watts (Rounded up)

Common Questions

What happens if my PSU is too small?

If your system draws more power than the PSU can provide, you will experience system instability, blue screens, or immediate shutdowns during heavy gaming or rendering. In extreme cases, a low-quality PSU might fail and damage other components.

Is an 80 Plus rating important?

Yes. While it doesn't change the wattage, the 80 Plus rating (Bronze, Silver, Gold, Platinum, Titanium) indicates how much power is lost as heat. A higher-rated PSU will use less electricity from your wall outlet to deliver the same internal wattage.

Should I buy a 1000W PSU "just in case"?

While over-specifying your PSU won't harm your PC (it only draws what it needs), it can be a waste of money unless you plan on adding a second GPU or upgrading to a flagship processor later. Using this power supply calculator helps you find the sweet spot between safety and cost.

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