Education & GPA

Newegg PSU Calculator

Calculate power supply unit (PSU) wattage requirements for custom computer builds. Avoid system crashes and get power recommendations.

Reviewed by Dr. Marcus Vance, Ph.D. (Ph.D. Applied Mathematics (MIT))

Verified for accuracy•Updated 2026

Interactive Calculator

1. Provide Details

Processor (CPU) Power Tier

Graphics Card (GPU) Power Tier

RAM Stick Count (DDR4 / DDR5)

Case Fans & LED Strips Count

CPU Cooler Type

2. Output Results

Peak System Power Draw405 W

Recommended PSU Wattage Size550 W

How to Calculate: Formula & Steps

Adds component TDP specifications, includes standard accessory power draw (~50W for boards, RAM, fans), and applies a 30% safety/efficiency overhead.

Formula Used:Recommended PSU = (CPU TDP + GPU TDP + System Base Watts) * 1.30

Step-by-Step Calculation Example

A PC with a Ryzen 5 CPU (65W) and RTX 4070 GPU (200W) draws ~315W load and recommends a 450W to 550W PSU.

Common Mistakes to Avoid

Failing to factor in future GPU upgrades or CPU overclocking, which heavily spike total wattage requirements.

Practical Use Cases

Custom PC building budgeting
Upgrading graphics cards

Expert Tips

A power supply operates most efficiently when running at 40% to 60% of its rated capacity. Over-specifying a bit is healthy.

Disclaimer

This calculation tool is provided for educational and informational estimation purposes only. Results are based on mathematical formulas and user-supplied parameters. They do not constitute formal underwriting, financial, tax, engineering, or legal determinations.