An editorial check of the premise that the calendar year creates one new carry-on measurement.
1 answer
A year in a headline is not enough to identify a new baggage rule. There is no single measurement you should apply to every 2026 journey; find the allowance for the airline operating your flight and the type of bag included with your ticket.
American Airlines’ current official page, for example, gives separate measurements for a main carry-on and an underseat personal item. It also allows for additional restrictions on some aircraft and at some airports. That is a much more specific basis for a decision than a claim that all carry-ons changed size for the new year.
If you have seen a post announcing a change, look for the airline name, the effective date and the official notice. Check whether the announcement concerns dimensions, included bag count, a weight allowance or the price of bringing a bag. Those are different changes even when a headline groups them together.
For a backpack you already own, there is no need to replace it simply because the year changed. Pack it as intended, measure the result and compare that with the relevant current allowance. Recheck before departure if the booking is far ahead.