Here's an interesting article from a guy testing his M1 MacBook Air's battery life/runtime on one of his regular day's working on the computer.
He didn't do anything different than he normally does to conserve battery power (such as being concerned about screen brightness & stuff like that)...he just did what he normally does. Granted his "normal day" may not be our "normal day".
Apple's stated battery life/runtime claims for the M1 MacBook Air are:
"
Apple reports that this model can provide up to 15 hours of "wireless web" and up to 18 hours of "Apple TV app movie playback."
This guy's runtime on one of his "regular days" (starting with 100% charged battery)...was 7 hours, 47 minutes:
I recently conducted a real-world, fly-on-the-wall M1 MacBook Air battery test. And the results were... surprising.
markellisreviews.com
Obviously 7 hours, 47 minutes is much shorter than the 15-18 hours claimed by Apple. But this should come as no surprise...manufacturers of laptop/notebook computers have always over-stated the battery life/runtime of their products (after all they are trying to sell you something).
Generally speaking many/most users don't use their laptop/notebook computers exactly the way Apple tests...thus almost all of use will get battery runtime on a single full battery charge less than Apple claims.
Sometimes this difference will be small...sometimes large. Really depends what you do on your laptop/notebook computer.
Nick