Customer Churn Rate Formula (with a Worked Example)

The customer churn rate formula is one of the simplest calculations in SaaS, and one of the easiest to get subtly wrong. At its core it answers a single question: of the customers you had at the start of a period, what share did you lose by the end? Get the inputs right and it is a reliable pulse on retention. Get them sloppy and you will chase phantom trends.

This article walks through the customer churn rate formula step by step, works a full example with real numbers, and covers the edge cases that trip people up, from mid-period signups to how you handle a shrinking base.

The Customer Churn Rate Formula

Here is the standard version:

Customer churn rate = Customers lost during period ÷ Customers at start of period × 100

Notice the denominator. You divide by customers at the start of the period, not the end and not the average. Using the starting count keeps the metric stable and comparable month to month. If you are new to the concept, our overview of what churn rate is covers the fundamentals before you dive into the math.

A Worked Example of the Customer Churn Rate Formula

Suppose you run a SaaS product and look at the month of June.

• Customers on June 1: 480
• Customers who cancelled during June: 24
• New customers who signed up during June: 60

Apply the formula using only the starting base and the losses:

24 ÷ 480 × 100 = 5% customer churn

The 60 new signups do not belong in this calculation. Churn measures how well you retain the customers you already had, so mixing in new acquisitions would mask the real retention picture. You ended June with 516 customers (480 − 24 + 60), but your churn rate for the month is still 5%.

Why the Denominator in the Customer Churn Rate Formula Matters

The most common mistake is using the wrong denominator. Watch out for these variations.

• Dividing by ending customers: This understates churn during growth and overstates it during decline, because the base moves with your results.
• Dividing by average customers: Some analysts use the average of start and end counts. It is defensible, but it produces a different number, so pick one method and stick with it.
• Counting new-and-churned customers: If someone signs up and cancels within the same month, decide up front whether they count. Most teams exclude them from the starting base since they were never part of it.

Consistency beats theoretical perfection. Whatever you choose, apply it the same way every period so your trend line means something.

Customer Churn vs Revenue Churn

The customer churn rate formula treats every account equally. A $15/month hobbyist and a $5,000/month enterprise both count as one churned customer. That is fine for measuring logo retention, but it can hide serious revenue damage.

If your churned customers skew large, revenue churn will look far worse than customer churn. To capture the dollar impact, pair this metric with the revenue churn rate formula, and consider tracking revenue churn as your primary health metric if you have wide price variation.

Choosing the Right Time Period

The customer churn rate formula works for any window, but the period you pick changes how you read it.

Monthly churn

Best for month-to-month products and fast feedback. Monthly numbers are volatile at small scale, so watch the multi-month trend, not one spike.

Annual churn

Better for businesses on annual contracts, where most cancellation decisions happen at renewal. Do not simply multiply monthly churn by 12, which overstates the annual figure because the base shrinks each month.

Annualizing the Customer Churn Rate Formula

A frequent error is turning monthly churn into annual churn by multiplying by 12. That overstates the loss, because each month's churn applies to a base that has already shrunk. The right approach uses retention, not churn, and compounds it.

Annual retention = (1 − monthly churn rate) raised to the power of 12

Return to our June example of 5% monthly churn. Monthly retention is 0.95, and 0.95 to the twelfth power is roughly 0.54. So annual retention is about 54%, and annual churn is about 46%, not the 60% you would get from multiplying. The gap widens as churn rises, so never shortcut the conversion when you present annual figures to a board or investor.

Segmenting the Customer Churn Rate Formula

A single blended churn number can hide the story that actually matters. Two companies can both report 5% churn while facing completely different problems, and the only way to see the difference is to run the formula across segments.

• By plan tier: if your cheapest tier churns at 9% and your top tier at 2%, the average tells you almost nothing useful.
• By cohort: comparing the churn of customers who joined in January against those who joined in June shows whether recent product and onboarding changes are working.
• By acquisition channel: customers from one channel may churn twice as fast as another, which changes how you value each source.

Segmenting turns a vanity number into a diagnostic. It points you at the specific tier, cohort, or channel driving the loss so you can act instead of guessing. To see how your figure stacks up against peers, compare it with average SaaS churn benchmarks before deciding whether it is a problem.

How to Track the Customer Churn Rate Formula Automatically

Running the formula once is easy. Running it correctly every month, across segments, while excluding trials and handling mid-cycle changes, is where manual spreadsheets fall apart. Proration, pauses, and downgrades all complicate the count.

StripeReport connects to your Stripe account with a read-only key and computes customer and revenue churn automatically each day, using a consistent starting-base method so your numbers stay comparable over time. You get the results by email or Slack without touching a spreadsheet. Once you understand where churn is coming from, our guide to reducing SaaS churn covers what to do about it.

Key Takeaways

• The customer churn rate formula is customers lost divided by customers at the start of the period, times 100.
• Always use the starting customer count as the denominator, and exclude new signups from the calculation.
• Customer churn weights every account equally, so pair it with revenue churn when your prices vary widely.
• Pick one method and time period, apply them consistently, and automate the calculation to avoid errors.