Electricity Cost Calculator
Work out what your PC costs to run per day, month and year from its power draw, your usage hours and your local electricity tariff.
What a gaming PC costs to run
Electricity is billed per kilowatt-hour: one kilowatt (1,000 watts) drawn for one hour. A 450 W system running for four hours uses 1.8 kWh, so the sum is simply watts, times hours, divided by 1,000, times your tariff.
cost = (watts × hours ÷ 1000) × price per kWh
Idle hours add up quietly
A machine left on all day at 70 W uses more over a month than a few hours of gaming at 450 W. If your PC is on far more than it is being used, sleep after 30 minutes is the single largest saving available, and costs nothing.
TDP is not the same as wall draw
Component TDP figures describe heat output under a specific test, not what the plug pulls. Real draw is higher, because the power supply itself is only 85–92% efficient — the rest becomes heat. A system pulling 450 W from an 88%-efficient unit draws about 510 W from the wall. Use the PSU Calculator to estimate your figure.
Does an efficient PSU pay for itself?
Moving from Bronze to Gold saves roughly 5% of your consumption. On a 450 W system used four hours a day that is a handful of currency units a year — real, but slow to repay a large price difference. The stronger arguments for a better unit are lower heat, quieter fans and better component quality.
The easiest saving of all
Cap your frame rate to your monitor's refresh rate. An uncapped graphics card will happily render 900 fps in a menu screen at full power for no benefit whatsoever. A frame cap can cut 100 W or more from typical gaming draw, and lowers noise and temperatures too.
Frequently asked questions
How much does it cost to run a gaming PC?
A typical mid-range system drawing 400W for four hours a day uses about 48 kWh a month. At UK prices that is roughly 13 pounds a month; in the US closer to 6 dollars. A high-end system with an RTX 5090 can easily double that.
Does leaving my PC on overnight cost much?
At 70W idle, eight hours a night is 0.56 kWh - about 17 kWh a month. It is not enormous, but it is roughly a third of what many people spend on actual usage, for no benefit. Sleep mode draws a few watts instead.
Is a more efficient power supply worth the money?
For the electricity saving alone, usually not - the difference between Bronze and Gold is around 5%. Buy the better unit for its lower heat output, quieter operation and higher build quality, and treat the saving as a bonus.
Does undervolting reduce my bill?
Yes, and noticeably. Undervolting a modern GPU commonly cuts 15-20% of its power draw for little or no performance loss, which also means less heat and slower fans.