Use this tool to accurately estimate the total power draw (in Watts) of your personal computer components and determine the ideal minimum size for your Power Supply Unit (PSU) to ensure system stability and future upgrade potential.
PC Wattage Calculator
Your Estimated Recommended PSU Wattage:
0 W This includes a 20% safety margin.Detailed Calculation Breakdown
Calculation steps will appear here after clicking ‘Calculate’.
PC Wattage Calculator Formula
Total Estimated Draw (TED) = (CPU Watts) + (GPU Watts) + (Base Overhead: 50W) +
(Storage Count * 5W) + (RAM Count * 5W) + (Accessories Watts)
Recommended PSU Wattage (RPW) = TED × 1.20 (20% Safety Margin)
Formula Source: Outervision PSU Calculator Methodology, Corsair PSU Guide
Variables Explained
- CPU TDP: The maximum thermal design power of your processor. This is a crucial input for peak system draw.
- GPU Power Draw: The maximum board power draw for your graphics card, often the single largest power consumer.
- Storage Devices: Estimated wattage per drive (5W for SSD/HDD) to account for spin-up and continuous operation.
- RAM Sticks: Estimated power consumption per DIMM (5W).
- Accessories Watts: Power used by case fans, liquid cooling pumps, USB devices, and RGB lighting.
Related Calculators
- Thermal Design Power Calculator
- PC Build Cost Estimator
- UPS Battery Life Calculator
- Overclocking Power Consumption Tool
What is PC Wattage?
PC Wattage is the total amount of electrical power, measured in Watts (W), that your computer system demands from the Power Supply Unit (PSU) under load. Accurate wattage calculation is essential because it determines the minimum capacity of the PSU needed to run your components safely and reliably. An undersized PSU can lead to system instability, random shutdowns (especially during gaming or stress tests), and long-term damage to components.
The required wattage is not a fixed number but fluctuates heavily based on the current workload. Components like the CPU and GPU draw very little power when idle but can spike dramatically to their maximum TDP ratings when running demanding applications. Therefore, a calculator must focus on estimating the *peak* instantaneous draw.
Furthermore, it is standard practice to select a PSU with a capacity significantly higher (typically 20-30% margin) than the total estimated power draw. This buffer ensures the PSU operates within its most efficient load range (usually 40-60%), reduces heat, and allows for minor future upgrades without needing a PSU replacement.
How to Calculate PC Wattage (Example)
- Identify Component TDPs: A user has a CPU with 125W TDP and a GPU with 300W Board Power.
- Calculate Auxiliary Draw: The system has 2 SSDs (10W total), 4 RAM sticks (20W total), and 30W for fans/lighting.
- Determine Total Estimated Draw (TED): $$ TED = 125W + 300W + 50W (Base) + 10W + 20W + 30W = 535W $$
- Apply Safety Margin: Apply the standard 20% safety margin to the TED. $$ RPW = 535W \times 1.20 = 642W $$
- Select PSU: Based on the 642W requirement, the user should purchase a PSU rated at 650W, 700W, or ideally, 750W for maximum efficiency and headroom.
Frequently Asked Questions (FAQ)
The 80 Plus rating (Bronze, Gold, Platinum) indicates a PSU’s efficiency, not its capacity. A Gold-rated 650W PSU will deliver 650W, but it will pull less power from the wall socket than a Bronze-rated 650W PSU to achieve that output, meaning better efficiency and less heat waste.
Overclocking significantly increases power draw beyond the manufacturer’s stated TDP/TBP. If you plan to heavily overclock, you should manually increase the CPU and GPU wattage inputs in the calculator (e.g., by 20-40%) to compensate.
No. You should always round the Recommended PSU Wattage (RPW) up to the next standard PSU size (e.g., 642W should round to a 650W or 700W unit). Using a higher capacity PSU ensures it runs cooler and quieter, improving its lifespan and efficiency.
These figures are usually found on the official product specification pages on the manufacturer’s website (AMD, Intel, Nvidia). TDP is the primary metric for CPUs, while Board Power or TBP (Total Board Power) is used for GPUs.