Net MRR churn: what net revenue churn is and how to calculate it

Net MRR churn measures how much recurring revenue the existing base lost, after subtracting the revenue that same base gained through expansion. It starts from the period losses (cancellations and downgrades) and subtracts the expansion generated by those who stayed, showing the net result of movement inside the book.

It is a revenue metric, not a customer metric: a single large customer who cancels weighs more than many small ones. And it always looks at the base that existed at the start of the period. New customer revenue enters elsewhere in the funnel and is never used to mask the churn of the base.

The formula starts from the MRR at the beginning of the period and looks only at what happened to those customers:

• Net MRR churn = (churned MRR + contraction MRR - expansion MRR) / starting MRR.
• Churned MRR: revenue lost to subscriptions that ended.
• Contraction MRR: revenue lost to downgrades and plan reductions.
• Expansion MRR: revenue gained from upgrades and upsells of existing customers.

Example: a base of $100k in MRR loses $8k to cancellations and $2k to downgrades, but gains $6k of expansion. Net MRR churn is (8 + 2 - 6) / 100, or 4%. Note that the expansion does not come from new sales, but from the existing book.

The difference between the two is one line of the formula: expansion. Gross MRR churn sums only the losses (cancellations plus contraction) over starting MRR and ignores any gain. Net subtracts expansion from those losses.

• Gross MRR churn: only what left. It never goes negative and measures the raw size of the leak.
• Net MRR churn: the balance after expansion. It can go negative and measures the net result of the base.

Looking at both together is what gives the full diagnosis. A low net with a high gross is a warning sign: the base loses a lot of revenue and it only stays hidden because expansion is holding up the result. If expansion slows, the leak appears.

Because net subtracts expansion, it can go negative. This happens when the revenue gained from upgrades in the base outweighs everything lost to cancellations and downgrades. It is the coveted negative churn: the existing base grows on its own, even without a single new customer coming in.

This is the most efficient growth engine a SaaS can have, because it does not depend on spending more on acquisition. It tends to come from models that grow with customer usage, charging per seat, per consumption or by value tiers, where customer success naturally pushes the bill up over time.

Net MRR churn is the mirror of Net Revenue Retention (NRR). One metric is practically the complement of the other: if the base retains 110% of revenue, net MRR churn is about -10%. If it retains 95%, net churn is about 5%.

• NRR above 100% equals negative net MRR churn.
• NRR below 100% equals positive net MRR churn.

They are the same reality told from two angles: NRR tells the glass half full (how much revenue stayed), net churn tells the glass half empty (how much net leaked out). Product and retention teams tend to track both in parallel, because each one highlights a different reading of the same movement.

Net MRR churn is one of the best thermometers of the long-term health of a SaaS, because it sums up in a single number whether the base grows or shrinks on its own. The lower it is (and better still, negative), the more the business sustains itself without relying only on selling to new customers.

The best subscription businesses run on negative net churn. The private SaaS survey by KeyBanc Capital Markets shows net revenue retention above 100%, which is the same as saying negative net MRR churn at the median. And, as SaaS Capital points out, retention tends to be stronger in larger contracts and weaker in self-serve, so the healthy benchmark depends on the audience the company serves.