The Real Cost of Running a Second Screen 24/7

A second monitor feels essential. Code on one screen, documentation on the other. Email here, Slack there. Productivity enthusiasts swear by dual setups. But that second screen draws power—and if you leave it on 24/7, the electricity bill adds up. Here’s what it actually costs, and how to cut it.

Where the power goes

A typical 27-inch LED monitor draws 30 to 50 watts at full brightness. A 32-inch or 4K panel can pull 50 to 80 watts. Leave one on 24 hours a day, 30 days a month, and a 40-watt monitor consumes about 29 kWh per month. At $0.15 per kWh (US average), that’s roughly $4.30. At $0.30 (parts of Europe), it’s $8.60.

Add a second screen and double it. A dual-monitor setup left on 24/7 can add $8 to $17 per month depending on panel size and electricity rates. Over a year, that’s $100 to $200. Not catastrophic—but noticeable.

Standby and sleep

Most monitors have sleep and standby modes. When idle, they drop to 1 to 3 watts. If your monitors actually sleep when you step away, the cost plummets. But many people disable sleep—or their PC keeps the displays awake—so the screens stay at full power.

Check your monitor settings and Windows or macOS power options. Enable display sleep after 10 or 15 minutes of inactivity. That alone can cut monitor power use by 80 percent or more for typical workday usage.

Brightness and size

Lower brightness reduces power. A monitor at 50 percent brightness uses significantly less than at 100 percent. And smaller panels use less than larger ones. A 24-inch 1080p monitor draws far less than a 32-inch 4K display. If you’re optimising for cost, size and brightness matter.

The bottom line

Running a second screen 24/7 adds roughly $4 to $9 per month per monitor depending on size and electricity rates. Enable sleep, lower brightness, and turn off when not in use—and the cost drops sharply. The productivity gain from a second screen may be worth it. The electricity cost of leaving it on all night probably isn’t.