Mark Spoonauer, Tom’s Guide:

Here’s how the Tom’s Guide battery test works. It surfs the web continuously at 150 nits of screen brightness, launching a new site every 30 seconds until the battery drains. For the iPhone 12 and iPhone 12 Pro, we ran this test over 5G and 4G, and the difference was pretty dramatic.

And:

The regular iPhone 12 lasted just 8 hours and 25 minutes over AT&T’s 5G network. Last year’s iPhone 11 lasted a whopping 11 hours and 16 minutes over 4G. To compare, we switched the iPhone 12 to 4G-only, and it endured for 10 hours and 23 minutes.

Follow the headline link, scroll down to the chart for the details but, in a nutshell, 5G took about 2 hours off the battery life for both the 12 and 12 Pro.

This shouldn’t stop you from buying an iPhone 12, and it shouldn’t stop you from using 5G. Just keep this in mind and plan accordingly.