PC Watt Calculator
Calculate total PC power consumption from individual components (CPU TDP, GPU TGP, RAM, storage, fans) to find the ideal PSU wattage for your build.
Calculate PC Power
Enter component TDP/TGP values to calculate total system power draw and recommended PSU.
How to Calculate PC Power Consumption
Total PC wattage = CPU TDP + GPU TGP + RAM + Storage + Fans + Motherboard. Add 20-30% headroom for power spikes, efficiency losses, and future upgrades. Choose a PSU rated at 1.25× your total to keep it in the efficient 50-80% load range.
Component Power Reference
| Component | Low Power | Mid Range | High End |
|---|---|---|---|
| CPU | 35-65W | 65-125W | 125-253W |
| GPU | 75-150W | 150-250W | 300-600W |
| RAM (per stick) | 3W | 5W | 8W |
| SSD (NVMe) | 3-5W | 5-8W | 8-12W |
| HDD | 5-8W | 8-12W | — |
| Case Fans (each) | 1-3W | 3-5W | 5-8W |
| AIO Cooler | 5-10W | 10-15W | — |
| Motherboard | 25-35W | 35-50W | 50-80W |
PSU Efficiency: 80 Plus Ratings
- 80+ White: 80% efficient (budget builds)
- 80+ Bronze: 82-85% efficient (mainstream choice)
- 80+ Gold: 87-90% efficient (recommended for gaming)
- 80+ Platinum: 89-92% efficient (enthusiast)
- 80+ Titanium: 90-94% efficient (workstation/server)
A 700W system with an 80+ Gold PSU (90% efficient) draws ~778W from the wall. With 80+ White (82%), it draws ~854W — costing more electricity over time.
Frequently Asked Questions About PC Power
What size PSU do I need for a gaming PC?
Most gaming PCs need a 650-850W PSU. A mid-range build (Ryzen 7 + RTX 4070) needs ~500W total, so 650W PSU. A high-end build (i9 + RTX 4090) needs ~700W total, so 850-1000W PSU.
Is it bad to have too much PSU wattage?
No, a higher-wattage PSU is not harmful — it simply provides more headroom. PSUs only draw what the system needs. However, running at very low load (<20%) reduces efficiency slightly. A PSU at 50-80% load operates at peak efficiency.
What is TDP vs TGP?
TDP (Thermal Design Power) is the maximum heat a CPU generates under sustained load. TGP (Total Graphics Power) is the maximum power a GPU card consumes including VRAM and VRM. Both approximate the component's maximum power draw in watts.
Do I need to account for power spikes?
Yes, modern GPUs (RTX 40/50 series) have transient power spikes 2-3× above their TGP rating for microseconds. A 300W GPU may spike to 600W briefly. PSUs with ATX 3.0 / PCIe 5.0 support handle these spikes. Budget an extra 100-200W for transient headroom.
How much electricity does a gaming PC use?
A typical gaming PC draws 300-500W while gaming, costing $0.04-0.06/hour at $0.12/kWh. At 4 hours/day gaming, monthly cost is $4.80-$7.20. Idle power is typically 60-120W.