How can Gandalf be younger than Legolas?

Giving his birthday as when he arrived in Middle Earth I guess

I get the astrix for gandalf, he wasn't born as much as sent to embody an avatar in middle earth. But why astrix for legolas?

IIRC Tolkien never states his age.

by the end Gandalf is barely a newborn

Geez Legolas, rob the cradle much?
Gimli is 5% of your age!

asterisk*

That is the official movie cannon age, but not canon from JRRT.

It is a reasonable estimate as he was probably born in the early Third Age. He is well over 500, based on his statement that 500 years since the building of Meduseld felt like "a little while". So, anywhere 2-3k yo is reasonable.

Magic wizards dropping from the sky fully formed are hard to pin an age on. He is either older than the creation of ME or we mark time from when he arrives on middle earth. (He entered existence before the beginning of time, participating in the "Music of the Ainur" which shaped the world.)

Legolas was born sometime in the Third Age (possibly early ~87TA per movie lore).

Gandolf arrived in 1000TA, after the other Wizards, around the time the shadow fell over greenwood/murkwood.