PC Power Consumption Calculator
This PC power consumption calculator splits your computer's cost between active use and idle time. Pick a preset that matches your setup, or enter your own wattage, to see what your computer actually costs to run.
Estimated cost
Enter your rate to see your estimate.
How this calculator works
Active-time kWh = active watts × active hours ÷ 1,000. Idle-time kWh = idle watts × idle hours ÷ 1,000. Add those together and multiply by 30 days for a monthly figure, then by your rate for cost. Splitting active and idle time matters because a modern computer draws far less power asleep than it does running.
The preset wattage figures come from a DOE-developed appliance energy table reproduced by Virginia Cooperative Extension (desktop CPU, monitor, laptop) and Jackery's appliance wattage reference chart for the gaming desktop figure, which that DOE-derived table doesn't cover. Gaming desktop wattage is a commonly cited commercial estimate, not a government-published figure, and varies enormously by the specific graphics card and components installed. Last checked September 2026.
Frequently asked questions
How many watts does a computer use?
It depends heavily on the setup: a basic desktop draws roughly 120 watts active, a laptop draws far less at around 50 watts, and a gaming desktop can climb past 500 watts under load once the graphics card kicks in. See our desktop computer and laptop guides for the full wattage breakdown by component.
Does a laptop really use less electricity than a desktop?
Yes, substantially less in most cases. A laptop's components are built for battery efficiency by design, typically drawing around 50 to 100 watts total, while a desktop's CPU and separate monitor together commonly draw 250 watts or more combined when both are active.
Why does my gaming PC cost so much more to run?
A dedicated graphics card under load is the biggest factor by far, and high-end cards alone can draw 300 watts or more, on top of the CPU, drives, fans, and monitor. That's why a gaming desktop's total draw can be several times higher than a basic desktop doing everyday tasks.
How can I reduce how much electricity my computer uses?
Enable sleep or hibernate mode for idle periods instead of leaving the screen on and the system awake, lower monitor brightness, and close background applications and browser tabs that keep the CPU working when you're not actively using the machine.
Related tools
- Laptop electricity guide
- Desktop computer electricity guide
- Power Consumption Calculator
- Electricity Usage & Cost Calculator
- Generator Wattage Calculator — if you're figuring out whether a backup generator can run your desktop during an outage.
This calculator provides estimates based on typical wattage figures and the numbers you enter. Actual electricity cost depends on your specific hardware, especially the graphics card in a gaming setup.