If it has a mottled brown hue with flecks of green, then the fruit is "firm ripe" - meaning that it is good to eat while not being too mushy.
But be warned, if they are too overripe, then the fruit can be too soft and form dark bruises on the flesh inside.
The colour chart was posted to Reddit yesterday by user q0__0p, who found it on a sticker on an avocado.
It's been upvoted more than 30,000 times, and attracted nearly 800 comments.
It's far from the only way you can tell if an avocado is ripe.
Some recommend taking off the short stumpy stem to see if it is green or brown underneath.
If it is green, then the fruit is not ripe. But if it is brown, it is ready to be eaten.
Others say you just need to give the fruit a few gentle squeezes to feel if the flesh inside is soft or too firm.
But these avocado fans recommend feeling the fruit all over to make sure you don't miss any mushy or overly firm patches.