Calculate customer retention rate from starting customers, ending customers, and new customers, then compare churn, net change, and target retention.
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Separate retained customers from newly acquired customers Customer retention rate is based on how many of the starting customers stayed through the period, not on the ending customer total alone.
Formula
Retention rate = ((Customers at end − New customers) / Customers at start) x 100
The ending customer count can grow even while retention weakens, so the calculator removes newly acquired customers before measuring how much of the opening base stayed.
Enter your customer counts Add the starting customer base, ending customer count, and newly acquired customers to calculate retention and churn for the same period.
A customer retention rate calculator is only useful if it separates retained existing customers from newly acquired customers. This page uses the standard retention formula, shows the retained base, churn complement, and net movement, and lets you compare the period with an optional target retention rate so the result can support real marketing and revenue-planning review.
What customer retention rate is measuring
Customer retention rate measures how much of the opening customer base is still active at the end of the period after stripping out newly acquired customers. That distinction matters because an ending customer total can rise even while retention weakens if acquisition activity is strong enough to mask the losses.
The metric is therefore a base-stability measure, not a growth measure on its own. It tells you how well the existing customer book held together before you give credit to new-customer acquisition.
How the formula works
The calculator starts with customers at the beginning of the period, subtracts newly acquired customers from the ending count to infer how many existing customers remained, and then divides that retained group by the opening base. The result is the retention rate for the same measured period.
That also means retention and churn are complements in this worksheet. If retention is 90%, churn is 10% for the same customer base and period. Looking at both together usually makes the movement easier to read than using retention alone.
Retention rate = ((Customers at end − New customers) x 100) / Customers at start
Calculates the share of the opening customer base that stayed through the period.
Churn rate = 100 − Retention rate
Shows the share of the opening customer base that was not retained.
Retained existing customers = Customers at end − New customers
Infers the remaining existing-customer base before the retention percentage is calculated.
Worked example: 1,000 customers at the start, 1,100 at the end, 200 new
Suppose a business starts the quarter with 1,000 customers, ends with 1,100, and acquired 200 new customers during the quarter. The retained existing-customer base is therefore 900, because 1,100 minus 200 equals 900.
Retention rate is 900 divided by 1,000, or 90%. Churn is the complement, 10%. Even though the total customer base grew by 100 overall, the company still lost 100 of the starting customers along the way. That is exactly why the retention formula removes new customers before measuring how much of the opening base stayed.
How to use the target retention comparison
A target retention rate converts a percentage goal into a retained-customer floor and a maximum losses count for the same opening base. That makes the goal easier to use in period reviews because the team can compare actual retained customers with the minimum retained base needed to stay on plan.
This is especially useful when acquisition is strong. A company may still grow the ending base and miss its retention target at the same time. The target comparison prevents growth from hiding retention pressure.
HubSpot — Customer retention metrics — Marketing operations reference on how retention metrics are used alongside broader service and customer-success measures.
Frequently asked questions
Why can the customer base grow while retention falls?
Because new-customer acquisition can offset losses from the opening base. A business may end the period with more total customers and still have lost a meaningful share of the customers it started with.
What is the difference between retention rate and churn rate?
In this worksheet they are complements for the same opening base and period. Retention shows the share of the starting customers who stayed, while churn shows the share who were not retained.
Why does the calculator subtract new customers from the ending count?
Because retention should measure how many of the original customers stayed. If new customers were left in the ending figure, the result could overstate true retention.
Is a target retention rate the same as a forecast?
No. It is a planning threshold for the same period and opening base entered here. It does not predict future retention or customer lifetime value on its own.
