How Much Electric
Does a Computer Use?
Computers vary enormously in power draw, from a 30W laptop on idle to a 600W gaming desktop under full load. Knowing your machine's typical draw plus your daily hours lets you work out the real running cost using one short calculation.
A typical UK home laptop uses 30 to 100 watts (0.03 to 0.1 kWh per hour) depending on use. A standard desktop uses 100 to 300 watts (0.1 to 0.3 kWh per hour). A gaming or workstation desktop under load uses 400 to 800 watts (0.4 to 0.8 kWh per hour). At the current Ofgem cap of 24.7p per kWh, that means a laptop costs roughly £14 to £45 per year for 4 hours daily use, a standard desktop costs £45 to £135 per year, plus a gaming rig costs £180 to £360 per year.
The figures that matter
Laptop
Idle to moderate use. Tablets sit lower at 5 to 15W.
Standard desktop
Office desktop with monitor, typical productivity workload.
Gaming desktop
Modern gaming rig under full GPU load. Higher with multiple monitors.
On standby
Never zero. Standby plus phantom draw runs 24/7 unless plug switched off.
Four things to consider
laptop vs desktop
Laptops are typically 3 to 6 times more efficient than desktops for the same general work.
monitor adds 30w+
A typical 27-inch monitor adds 30 to 50 watts. Multiple monitors stack the cost.
gaming spikes the bill
Modern GPUs draw 200 to 450W under load. Running for 4 hours daily makes a measurable difference.
sleep modes save 80%+
Sleep plus hibernate cut idle draw to a few watts. Configure your machine to sleep when idle.
How to work out your computer's actual running cost
The figure on the power supply (e.g., "550W PSU") is the maximum it can deliver, not the typical draw. Real-world consumption is usually 40 to 70 percent of that rating depending on workload. The honest way to know is to either look up the typical figures for your model or use a plug-in energy monitor.
Real numbers at 24.7p per kWh (Q2 2026 Ofgem cap):
- 30W laptop, 4 hrs daily: 0.12 kWh per day, 3.7 kWh per month, roughly 92p per month or £11 per year.
- 60W laptop, 8 hrs daily: 0.48 kWh per day, 14.4 kWh per month, roughly £3.56 per month or £43 per year.
- 200W desktop, 4 hrs daily: 0.8 kWh per day, 24 kWh per month, roughly £5.93 per month or £71 per year.
- 200W desktop, 8 hrs daily: 1.6 kWh per day, 48 kWh per month, roughly £11.86 per month or £142 per year.
- 500W gaming PC, 4 hrs daily: 2 kWh per day, 60 kWh per month, roughly £14.82 per month or £178 per year.
- 700W gaming PC, 4 hrs daily: 2.8 kWh per day, 84 kWh per month, roughly £20.75 per month or £249 per year.
The phantom load nobody talks about. A desktop in sleep mode draws 5 to 15W. That sounds trivial. Across 16 hours of overnight sleep mode every day for a year, that adds up to 30 to 90 kWh, costing £7 to £22 per year. Across a household with multiple machines, monitors, plus chargers, phantom loads can add up to £50 to £100 per year unnoticed.
Where extra draw hides:
- Monitors. A 27-inch monitor adds 30 to 50W. A 32-inch curved 4K display adds 60 to 100W.
- External GPUs plus eGPU enclosures. Add 200 to 400W when active.
- Hard drive arrays plus NAS units. 20 to 80W continuously.
- Speakers plus audio interfaces. 5 to 30W when on.
- Always-on peripherals. Webcams, hubs plus dongles all add a few watts each.
Real number ranges
Annual computer running cost (UK 2026)
Energy use through a typical computer day
power-up spike
Brief peak draw at startup. 30 to 90 seconds. Negligible cost contribution.
background tasks
Most of the working day. 30 to 150W depending on machine. Consistent moderate draw.
working load
Document editing, video calls, browsing. 80 to 250W desktop. 30 to 80W laptop.
peak load
Gaming, video editing, 3D rendering. 400 to 800W on desktop. Spikes plus dips with the workload.
Four ways to cut computer running costs
Switch off at the wall
Plug the computer plus monitor into a switched extension lead. Off at the wall means zero phantom draw overnight.
Configure sleep timers
Set the display to sleep after 5 minutes plus the machine to sleep after 15. Default Windows plus macOS settings are often more wasteful.
Match the tool to the task
Browsing on a 600W gaming PC wastes electricity. Use the laptop for light tasks plus the desktop only when needed.
Check your monitor brightness
Most monitors ship at maximum brightness. Drop it to 60 to 70 percent. Saves around 20 percent of monitor draw.
Compare the options
Laptop
- •30 to 100W typical across the working day.
- •Built-in display already counted in the wattage figure.
- •Battery acts as a buffer if mains drops. No data loss on power blip.
- •Around £11 to £45 per year at 4 hours daily home use.
- •Less power per task but performance ceiling lower than equivalent desktop.
Desktop computer
- •100 to 800W typical depending on workload plus components.
- •Monitor adds 30 to 100W on top of the tower draw.
- •No internal battery. Mains drop means data loss unless on a UPS.
- •£70 to £360 per year at 4 to 8 hours daily depending on spec.
- •More power per task when needed but higher idle baseline.
Computers are one of the easiest appliances to optimise once you know the figures. Our full Appliances hub covers running costs across every major household appliance.
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Three further computer plus electronics running cost articles. how much electric does a pc use drills further into desktop figures. how much electric does a ps5 use covers the consoles equivalent. how much electric does a tv use sets the related living room baseline.