How to read a cohort chart in five minutes

A cohort chart looks dense, but it holds only three ideas. Each row is a group of people who signed up in the same week. Each column is how many weeks later you are looking. Each cell is the share of that group still active.

Set a timer for five minutes and read it in three passes.

Pass one: the first column

Look at week one only. If 100% of a cohort starts and 38% come back in week one, that 38% is your first big drop. Compare it down the rows. If newer cohorts return at 44% and older ones at 35%, onboarding got better. Give this pass one minute.

Next, read across a single row. A healthy curve falls fast, then flattens. If it keeps sloping toward zero at week eight, people are not finding a habit.

Pass two: the diagonals and the breaks

Now look for stripes. A diagonal stripe means something happened on one calendar date and hit every cohort at once, such as an outage or a pricing change. A vertical stripe means one week of life is weak for everyone, often the week a free trial ends.

Finish with a note: one sentence about what you saw and one question for the team. If you cannot write the sentence, your rows are too thin. Switch from weekly cohorts to monthly ones and look again.