Cradle it in your palm and press gently with your whole hand: a slight, even give means it is ready. Color alone is unreliable because some varieties stay green when ripe.
What to check
Feelslight give under gentle palm pressure. Rock hard usually needs around 2 to 4 days on the counter (check daily, the counter decides, not the calendar); mushy or dented is past it.
Lookdarkening skin suggests ripening on Hass, but check feel, not color.
At home onlyflick the small stem cap. Green underneath means ripe, brown means overripe. Do not do this in the store, it opens the fruit to mold.
Common mistakepressing with fingertips. That bruises the flesh, and it is why so many avocados are brown inside by the time they are bought.
Written by the team behind RIPE, a free app that reads a photo of the whole produce pile and rings the ripest ones. Every cue above is one you can check with your own hands, and it all works with no app at all.