How Much Would It Cost To Leave Your PC On 24/7? Idle Is Cheaper Than You Might Think

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Calculating how much leaving your computer running all the time will inflate your electricity bill is easy with the right information, and while it's difficult to give a broad estimate, it's likely cheaper than you'd imagine. Assuming you use a casual desktop PC or laptop for eight hours out of the day, and you're leaving it idle for the other 16 hours, you could be adding as little as $2 and as much as $5 per month to your energy bill.

The exact amount depends on many factors, including what kinds of components make up your system, what's still running when the PC idles, and, of course, the energy costs where you live. With a powerful gaming rig or a higher regional rate, the cost can easily balloon to $10, or even higher. It also gets more expensive if you're keeping the monitor awake during those 16 hours, or if you're running tasks while it idles.

Use my PC as an example: a five-year-old general-purpose desktop with 12 GB of RAM and a mid-range graphics card. In my testing with a P4460 Kill A Watt EZ meter, the tower's average idle power draw (with the monitor turned off) was close to 30W, equating to 0.03 kWh. Multiplying that rate by 16 and then by 30 for the hours and days, I can calculate that leaving my PC on uses 14.4 kWh every month. According to the U.S. Energy Information Administration (EIA), the average cost of energy for American homes in July 2026 was around 18.3 cents per kWh, bringing my monthly cost to $2.64. Keeping my budget monitor awake resulted in a combined idle draw of 40W, so I'm reaching past $3.50 per month.

While a basic PC or laptop may be cheap to leave running 24/7, your actual costs are hugely influenced by the hardware in your PC, the RAM in particular. That means it gets lot pricier if you have a high-caliber gaming or media-rendering PC. Based on reports from enthusiasts on Reddit in the PC watercooling subreddit, a common idle power draw for pro-level systems was around 100W. So, if you have a reasonably powerful rig, the cost of idling 16 hours per day goes up to almost $9 per month.

Some reported much higher, getting up to 300W at idle, bringing their average monthly cost all the way to almost $30. That's a few hundred dollars a year, and that's still ignoring the cost of actively using the PC for the other eight hours a day. People who can afford to build such a beastly rig, of course, probably won't be hurt by a monthly idle operating cost like that anyway. Still, it's worth keeping in mind the long-term pressure on your wallet a powerful PC has in the case that you're saving up for one, especially if you want to leave it on all the time.

Short of petitioning for government regulation, you have little say over the costs of energy where you live. However, the energy consumption of running your PC day and night is something you can take some control over. For example, the more apps you leave running, the more your idle power consumption is. In my testing, leaving Discord, Slack, a file server, and a music player running added one to two watts to the idle power consumption. That doesn't sound like much, but the cost will certainly add up over months or years.

Of course, running intensive programs like video renderers and gaming servers while you're away would dramatically increase the cost. You can sometimes mitigate these issues by turning off performance power profiles or even undervolting your GPU. It's also dramatically affected by whether or not (and how long) you let your PC sleep or hibernate. Putting my PC to sleep instead of letting it "actively" idle cut my average power consumption all the way back to around 2W, making the cost just a couple of dimes per month.

It's also important you look closely at your electricity bill. That EIA report noted that average rates vary by region from around 15 cents all the way up to 41 cents per kWh in non-contiuguous states. Variable rate energy plans that adjust the price throughout the 24-hour cycle also have an effect. It pays to read your energy bill closely so you can get an accurate understanding of your PC's operating costs.