The PSU Calculator determines the wattage needed for your PC power supply based on your components.
Select your CPU, GPU, RAM, storage, and fans. Get the total wattage, recommended PSU tier with 20% headroom, and an 80 Plus certification guide.
Calculator information
📋 How to use this calculator
- Select the CPU model you are using (or an equivalent based on its TDP in watts).
- Pick the GPU or enter its TGP in watts; make sure it matches the variant (OC vs reference).
- Enter the number of RAM modules (typically 3-5 W per DDR4/DDR5 stick).
- Add storage: HDD ~6-8 W, SATA SSD ~3 W, NVMe SSD ~5-8 W.
- Enter the number of case fans, RGB lighting, and high-draw USB peripherals.
- Review the total load, then choose a PSU with at least 20% headroom above total (ideally 30-40% for efficiency sweet-spot).
🧮 Estimated PSU Power Requirement
Recommended_PSU = (CPU_TDP + GPU_TGP + RAM + Storage + Fans + Misc) × 1.20
- CPU_TDP: processor TDP (W)
- GPU_TGP: total graphics power of the GPU (W)
- RAM: number of modules × 3-5 W
- Storage: number of drives × average draw
- Fans: number of fans × 2-3 W
- 1.20: 20% headroom factor for stability and efficiency
20% headroom is the minimum; PSUs are most efficient at 40-60% load, so many builders use 30-50% margin.
💡 Worked example: Mid-range gaming build: Ryzen 5 + RTX 4060
Given:- CPU Ryzen 5 7600: 105 W
- GPU RTX 4060: 115 W
- RAM 2x 16 GB DDR5: 8 W
- 1 NVMe SSD + 1 HDD: 14 W
- 3 case fans: 9 W
- Peripherals/RGB: 10 W
Steps:- Total load: 105 + 115 + 8 + 14 + 9 + 10 = 261 W
- Add 20% headroom: 261 × 1.20 = 313 W
- Pick the next standard capacity: 550 W (about 75% headroom)
- Choose 80 Plus Bronze or Gold for at least 82-87% efficiency
Result: A 550 W 80 Plus Gold PSU is sufficient; operational load lands around 47% of capacity.
❓ Frequently asked questions
Does a higher-wattage PSU always use more electricity?
No. A PSU only supplies the power the components draw, not its maximum capacity. An 850 W PSU delivering 300 W to the system pulls about 300 W from the outlet (plus efficiency losses). What determines power use is the 80 Plus efficiency rating and the workload, not the wattage label.
What is the difference between 80 Plus Bronze, Gold, and Platinum?
The 80 Plus certification measures AC-to-DC conversion efficiency at 20%, 50%, and 100% load. Bronze is about 82-85%, Gold 87-90%, Platinum 90-94%. The annual electricity cost difference is modest at US residential rates (~$0.16/kWh per EIA), but efficient PSUs generate less heat and typically use higher-quality components.
What is ideal PSU headroom?
Minimum 20% above peak consumption. Common practice is 30-50% so the system operates in the 40-60% load range where most PSUs are most efficient. Headroom also accommodates capacitor degradation that commonly appears after 3-5 years of use.
Do I need a 12VHPWR PSU for RTX 40-series cards?
RTX 4070 and above require the 12VHPWR (12+4 pin) connector per ATX 3.0/PCIe 5.0 specs. The RTX 4060 and 4060 Ti still work fine with an 8-pin adapter. Native ATX 3.0 PSUs are preferred because they are designed to handle modern GPU transient spikes up to 200% of TDP for microseconds.
Are cheap PSUs without 80 Plus certification safe?
Uncertified PSUs often use sub-spec components and can deliver unstable voltages that damage motherboards or SSDs. For builds over $400, it's strongly recommended to pick a PSU certified to at least 80 Plus Bronze from reputable brands like Seasonic, Corsair, FSP, EVGA, or Super Flower.
📚 Sources & references
Last updated: May 11, 2026