The basic formula is
(Average Load in kW) x (Hours of Use Per Day) x (365 Days) x (Cost per kWh) = Estimated Annual Cost Let's run through a practical example. Say you have a mid-range build that our calculator estimates will draw about 400W while gaming. You play for about 3 hours every day. The average cost of electricity in the US is around $0.17 per kilowatt-hour (kWh). First, we convert the wattage to kilowatts: 400W / 1000 = 0.4 kW. That's the cost for your gaming time. Remember to also account for idle time. When you're just browsing the web or watching videos, that same PC might only draw 80W (0.08 kW). If you do that for another 4 hours a day, that's an additional $16.79 per year. The total is just over $90 a year to run your PC. Our calculator automates this math for you, giving you a personalized estimate based on your parts and usage. This calculation also highlights why PSU efficiency matters. If you used a less efficient 80 Plus Bronze PSU in that scenario, the power drawn from the wall might be 470W instead of 440W (for a Gold PSU) to get the same 400W to your components. Over a year, that small difference adds up, costing you an extra $5-$10. It's not a huge amount, but over the 10-year life of the PSU, a more efficient unit can easily pay for its initial price premium.
- Now, plug it into the formula
- 0.4 kW * 3 hours/day * 365 days/year * $0.17/kWh = $74.46 per year.


