What Is Retention Rate? Calculation Methods and the Difference from Retention Ratio

"How is retention rate different from the retention ratio I hear about so often?"—this is one of the first things people stumble over when they start learning about metrics. The short answer is that the two are used to mean essentially the same thing. That said, there are several points to watch out for when it comes to the formulas and measurement methods. In this article, we organize the meaning of retention rate and how to calculate it, its relationship to the retention ratio, the difference from the often-confused churn rate, and the benefits and tips for improving it—all from a practical standpoint.

What Is Retention Rate?

Retention comes from the English word meaning "to keep" or "to maintain." In marketing, it refers to "retaining existing customers"—getting customers to keep using your products or services over time.

Retention rate is a metric that quantifies the proportion of customers who continue using a service within a given period. In Japanese it is translated with terms such as "existing customer retention rate," "stickiness rate," or "continuation rate," and it serves as a gauge of customer satisfaction and attachment to a service. The higher the figure, the better the relationship you have built with customers, and the more stable your ability to generate revenue.

In SaaS and subscription-style businesses in particular, whether customers keep using the service after signing up directly drives revenue. For that reason, retention rate is treated as one of the most important indicators reflecting the health of a business.

The Difference Between Retention Rate and Retention Ratio

The first thing to understand is that "retention rate" and "retention ratio" basically point to the same thing. Both "rate" and "ratio" express a proportion, and they are simply two ways of rendering the same underlying concept. In other words, they differ only in wording, while the concept they refer to is identical.

Any variation in terminology across articles and media simply reflects a preference in expression—whether to keep the English term or to translate it. Depending on the context, terms such as "customer retention rate," "stickiness rate," or "continuation rate" may be used, but all of them are, at their core, metrics that show how well you are retaining customers.

What you should actually watch out for in practice is not the difference in wording, but the variation in measurement method—"which formula, which period, and which definition of a customer" you are measuring with. Even with the same term "retention rate," if the definition differs, the meaning of the figure changes completely.

How to Calculate Retention Rate

There are several formulas for retention rate depending on your goal. The two most common are as follows.

(1) A simple formula that looks at retention of new customers

Retention rate (%) = Number of retained customers ÷ Number of new customers × 100

For example, if you acquired 1,000 new customers in a given month and 500 of them were still using the service one month later, the result is "500 ÷ 1,000 × 100 = 50%." This is an intuitive, easy-to-understand formula often used in apps and web services to see "how many of the acquired users remained."

(2) A formula that looks at retention across the entire customer base in a period

Retention rate (%) = (Customers at end of period − New customers acquired during period) ÷ Customers at start of period × 100

This formula measures "how many of the customers you originally had remained." For example, if you had 1,500 customers at the start of the period, acquired 200 new customers during the period, and had 1,400 at the end, the result is "(1,400 − 200) ÷ 1,500 × 100 = 80%." The key point is that by subtracting the newly acquired customers from the end-of-period total, you isolate the pure "number of retained customers."

Whichever formula you use, it is essential to clearly define the "target period." If you calculate without setting a period, you can end up with incorrect figures—such as the number of retained customers exceeding the number of new customers, pushing retention rate above 100%.

Three Things to Decide Before Calculating

The retention rate formula itself is simple, but if you do not decide on the underlying definitions, the figure can take on a life of its own. At a minimum, align the following three items across your organization.

• Definition of a customer: Do you include free users, only paying subscribers, or only people who used the service a certain number of times? What you count as a "customer" changes the figure significantly.
• Measurement period: Do you look at it daily, weekly, or monthly? For a service meant to be used every day, set it short; for one used less frequently, set it longer.
• The action that counts as "retention": Does logging in alone count as retention, or do they need to use a specific feature or keep an active subscription? Decide which behavior you treat as "being retained."

There are also multiple schools of thought on measurement method: "classic retention," which checks whether a customer is active on a specific day a set period after starting the service, and "rolling retention," which checks whether they used it at least once within an arbitrary period, among others. It is important to choose based on your business model and on "what decision the metric is for."

The Relationship with Churn Rate

A metric worth understanding alongside retention rate is churn rate (cancellation or attrition rate). Churn rate shows how many customers left within a given period, and it has a two-sides-of-the-same-coin relationship with retention rate.

Retention rate (%) + Churn rate (%) = 100%

For example, if retention rate is 80%, then churn rate is 20%. Whereas retention rate is a metric that looks at "how many remained," churn rate looks at "how many were lost." Because they view the same phenomenon from opposite sides, improving one improves the other. Using churn rate for analyzing the causes of attrition and retention rate for conveying the degree of stickiness in a positive light makes them easier to handle on the ground.

The Benefits of Improving Retention Rate

Improving retention rate also has a major effect on revenue. Let us organize the key benefits.

• Higher LTV (customer lifetime value): As more customers keep using the service, the lifetime profit each one brings grows, and LTV increases. Retention rate and LTV are closely linked.
• Stable revenue and lower acquisition costs: Acquiring new customers generally costs more than retaining existing ones. If you can retain existing customers, you can build up revenue stably without leaning on new acquisition.
• More upsell and cross-sell opportunities: Customers who keep using the service have high satisfaction and are more receptive to proposals for higher-tier plans or related products, making it easier to raise the average order value.
• Awareness growth through word of mouth and UGC: Highly satisfied loyal customers spread positive reviews on social media and by word of mouth, which also leads to new customer acquisition.

Tips for Improving Retention Rate

Improving retention rate is not a quick-acting measure like advertising; it is an effort to steadily build trust with customers. Here are the levers that tend to be effective in practice.

1. Refine onboarding: Whether customers feel the value of the service right after they start using it greatly influences subsequent retention. Improving the quality of that first experience is the top priority.
2. Raise the quality of customer support: The handling of inquiries and the speed of problem resolution are directly tied to satisfaction. Review the experience at every touchpoint.
3. Catch signs of churn with cohort analysis: By grouping customers by factors such as their sign-up month and tracking retention over time, you can identify at which timing and in which segment churn is occurring.
4. Set leading indicators and run a PDCA cycle: By placing intermediate indicators such as "usage rate of a specific feature" as leading KPIs—not just the final retention rate—you can verify the effect of measures more quickly.
5. Tackle it across departments: Reasons for churn span multiple departments—product, marketing, support, and more. Rather than leaving it to a single department, facing it as an organization-wide issue leads to fundamental improvement.

Conclusion

Retention rate is a metric that shows the proportion of customers who continue using a service within a given period, and "retention ratio" is the same thing in essence, differing only in wording. What matters is not the difference in terms, but aligning the definition of a customer, the measurement period, and the action counted as retention, and measuring with a consistent standard. Keep in mind its two-sides-of-the-same-coin relationship with churn rate, and while staying mindful of benefits such as higher LTV and stable revenue, steadily run a PDCA cycle through onboarding improvements and cohort analysis. The starting point for improving retention rate is not measuring the number itself, but turning that number into actions that deepen your relationship with customers.