How Much Electric
Does a PC Use?
A desktop PC's electricity use depends almost entirely on the work you put through it. An office PC running productivity software draws a fraction of what a gaming rig with a high-end GPU draws. This guide gives honest UK figures for every common PC build at the current 24.7p per kWh.
A UK desktop PC typically uses 80 to 800 watts depending on its specification plus current workload. At the current Q2 2026 Ofgem unit rate of 24.7p per kWh, an office PC at 100W idle costs 2.5p per hour. A productivity PC at 200W typical use costs 4.9p per hour. A gaming PC drawing 500W under load costs 12.4p per hour. Across 8 hours daily use, that translates to £73 per year for an office PC plus £359 per year for a gaming PC.
The figures that matter
Office PC
Modern office desktop, productivity workload, single monitor.
Productivity
Mid-range desktop with multiple monitors plus content work.
Gaming PC
Modern gaming rig with discrete GPU under load. Spikes higher with multi-GPU.
Sleep mode
Phantom draw on standby. Cumulative across overnight hours plus weekends.
Four things to consider
PSU rating is not actual draw
A 750W PSU usually runs at 30 to 60 percent of capacity. Real draw is far below the badge figure.
GPU is the biggest variable
Modern gaming GPUs draw 200 to 450W under load. Office work draws a fraction of this.
Monitors stack up
Each 27-inch monitor adds 30 to 50W. Multi-monitor setups add 90 to 150W to baseline draw.
Sleep settings save 80%+
Aggressive sleep timers cut idle waste. Default Windows settings are often more wasteful than they need to be.
PC electricity by build type plus workload
Desktop PC running costs split sharply by what the machine actually does. An office PC streaming a Teams call with a browser open might draw 80W. The same PC compiling code or rendering video might briefly hit 300W. A gaming PC running modern AAA titles might draw 500 to 700W steady for hours. Treating a PC as a single fixed wattage is misleading.
Real numbers at 24.7p per kWh (Q2 2026 Ofgem cap):
- Office PC, 100W average, 8 hrs daily: 0.8 kWh per day, 24 kWh per month, roughly £73 per year.
- Productivity PC, 250W average, 8 hrs daily: 2 kWh per day, 60 kWh per month, roughly £182 per year.
- Gaming PC, 500W average, 4 hrs daily gaming plus 4 hrs idle at 100W: 2.4 kWh per day, 72 kWh per month, roughly £219 per year.
- Heavy-use gaming PC, 700W average, 4 hrs daily: 2.8 kWh per day, 84 kWh per month, roughly £249 per year.
- Workstation PC, 400W average, 8 hrs daily: 3.2 kWh per day, 96 kWh per month, roughly £290 per year.
Where the wattage actually goes inside a gaming PC:
- GPU: 150 to 450W under load (the biggest single component).
- CPU: 65 to 250W under full load.
- RAM, motherboard, drives, fans: 30 to 80W combined.
- Monitor (27-inch): 30 to 50W.
- Peripherals (keyboard, mouse, USB hub, headset, speakers): 5 to 30W combined.
The PSU rating myth. A PC with a 750W power supply does not draw 750W. The PSU is rated for maximum delivery capacity. Real draw under load is typically 30 to 60 percent of capacity. A modern 80+ Gold rated PSU is around 90 percent efficient at typical load, so the wall draw is slightly higher than the actual component consumption.
Real number ranges
Annual desktop PC running cost (UK 2026, 8 hrs daily)
Energy use through a typical PC working day
Power-up
Brief wattage spike at startup. Negligible cost contribution to the daily total.
Background tasks
Most of the working day. 60 to 150W on office PCs, 100 to 200W on gaming rigs at desktop.
Working load
Document editing, video calls, browsing. 100 to 250W typical depending on PC class.
Peak load
Gaming, video editing, 3D rendering. 400 to 800W on desktop. Spikes plus dips with the workload.
Four ways to cut desktop PC running costs
Switch off at the wall
Plug the PC plus monitor into a switched extension lead. Off at the wall means zero phantom draw overnight.
Configure sleep timers
Display sleep after 5 minutes, machine sleep after 15. Default Windows plus macOS settings are often wasteful.
Match the tool to the task
Browsing on a 600W gaming PC wastes electricity. Light work on a laptop, heavy work on the desktop.
Drop monitor brightness
Most monitors ship at maximum brightness. Drop to 60 to 70 percent. Saves around 20 percent of monitor draw.
Compare the options
Office or productivity PC
- •80 to 250W typical across the working day.
- •£70 to £210 per year at 8 hours daily use.
- •Low component thermal load. Rarely spikes the household electrical demand.
- •Single 27-inch monitor common. Adds 30 to 50W on top of tower draw.
- •Suits typical office work. No real benefit from gaming-class hardware.
Gaming or workstation PC
- •400 to 800W under load with peaks higher during full GPU work.
- •£220 to £360 per year at 4 hours gaming plus idle time.
- •High thermal output. Adds noticeable heat to the room during heavy sessions.
- •Often multiple monitors plus peripherals adding 90 to 200W extra.
- •Suits gaming, content creation, 3D modelling plus heavy data work.
Desktop PC running costs are one of the larger variable loads in modern UK homes. Our full Appliances hub covers running costs across every major UK household appliance.
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This article is one chapter inside our complete Appliances knowledge base. The hub covers running costs across every major household appliance from kettles to heat pumps.
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Three further computer plus electronics articles in the same hub group cover the related questions. The first is how much electric does a computer use covering the broader category. The second covers how much electric does a ps5 use for the consoles equivalent. The third is how much electric does a tv use for the related living room baseline.