Canonical formula calculator
RETENTION RATE
What percentage of your customers stick around — and what percentage you have to replace just to stay flat.
Worked example
How the number is worked out
The scheduling app again, counting who was still there at the end of the month.
Starting from
Working
Ninety-five percent stayed. Retention and churn are the same fact read from opposite ends — this month cost 21 accounts, and every one has to be replaced before the next sale counts as growth.
What this tells you
Retention rate is the percentage of customers from the start of a period who are still your customers at the end. It is the most direct measure of whether what you sell keeps people coming back. Monthly retention above 95% is excellent for most B2B SaaS; under 90% means you are running fast just to stand still.
When to use it
Calculate retention every month and watch the cohort trend over time. Retention that is improving means you are getting better at keeping customers. Retention that is flat or declining while you are growing means you are masking churn with new acquisition — and that math eventually catches up.
What it doesn’t tell you
Retention rate by itself does not tell you which customers are leaving. Losing 5% of small customers is a different reality than losing 5% of your largest. Pair retention with revenue retention (which weights by customer value) for the full picture.
Reckon it, don’t just calc it
A calculator gives you today’s number. Reckon takes your plan to make your own money and checks it against what’s real — your margin, your price, what it takes to hit the take-home you want. No AI, no guessing — the same input always gives the same answer.