SaaS metrics beyond MRR: NRR, expansion, churn and CAC payback

MRR tells you how big the business is. It does not tell you whether it is healthy. Two companies with identical MRR can be heading in opposite directions, and the difference shows up in the metrics underneath: how much existing customers grow or shrink, which customers leave, and how long it takes to earn back what a new customer cost.

Why MRR alone misleads

Take two companies, both at $100,000 MRR this month.

Company A signs twice as many new customers and still grows more slowly. Its existing base shrinks by 3% a month (+$1,000 - $4,000); Company B's grows by 3%. Company A has to replace $4,000 of lost revenue every month before it grows at all. MRR on its own shows neither of these.

Net revenue retention (NRR)

NRR measures how much revenue you keep and grow from customers you already had, leaving new customers out entirely.

NRR = (starting MRR + expansion - contraction - churn) / starting MRR

Worked example over twelve months. The customers who were paying you at the start paid $100,000 a month. Over the year:

• expansion (upgrades, extra seats, add-ons): $15,000
• contraction (downgrades): $3,000
• churn (cancellations): $7,000

NRR = ($100,000 + $15,000 - $3,000 - $7,000) / $100,000 = 105%

Above 100%, your existing customers pay more at the end of the period than at the start, so the business grows even with no new sales. Below 100%, new sales first have to fill a hole.

Two things to get right:

• Only the starting customers count. New customers and reactivated customers are left out; they belong in growth, not retention.
• Say which period you mean. Companies usually report NRR over 12 months. A monthly figure is useful internally but not comparable with a yearly one.

Gross revenue retention (GRR)

GRR is the same calculation without expansion:

GRR = (starting MRR - contraction - churn) / starting MRR

In the example: ($100,000 - $3,000 - $7,000) / $100,000 = 90%. GRR cannot go above 100%, which makes it the honest measure of how leaky the base is. A company with 105% NRR and 90% GRR depends on expansion to cover real losses. If expansion slows, NRR falls quickly.

Look at it by segment

A blended NRR can hide a problem. Split it by plan, company size, acquisition channel and signup cohort. It is common to find one segment above 110% carrying another below 90%.

Expansion revenue

Expansion rate = expansion MRR in the period / starting MRR

In the example, $15,000 / $100,000 = 15% a year. Useful questions to ask of expansion:

• Which plan do expanding customers start on, and how long until they first upgrade?
• Is expansion coming from seats (the customer's team grows) or from add-ons (they use more of the product)?
• Is it concentrated in a few large accounts? If three customers make up most of it, it is fragile.

Churn: count customers and revenue separately

Customer (logo) churn = customers lost in the period / customers at the start

Gross revenue churn = MRR lost to cancellations and downgrades / MRR at the start

Say you start the month with 200 customers paying $100,000. You lose 6 customers (3% logo churn), but they paid $5,000 between them, so revenue churn is 5%. The customers leaving pay more than average, which is worth a closer look at your larger accounts. If the numbers were the other way round (5% logo churn, 2% revenue churn), you would be losing mostly small accounts.

Two ways to go deeper:

• Churn by cohort. Group customers by signup month and track when they leave. If most churn happens in the first 90 days, the problem is onboarding or fit, not the product over time. The guide to cohort analysis shows how to build the table.
• Churn by reason. Record a reason on every cancellation (price, missing feature, went out of business, switched to a competitor, no longer needed) and count them each quarter. Reasons you can act on and reasons you cannot need different responses.

Do not multiply a monthly churn rate by 12. Each month churns from a smaller base: 3% a month is about 31% a year, from 1 - (1 - 0.03)^12.

CAC payback

How many months of gross profit it takes to earn back what you spent to win a customer.

CAC payback (months) = CAC / (new MRR per customer × gross margin)

Example: you spend $6,000 in sales and marketing per new customer, the average new customer pays $500 a month, and gross margin is 80%.

$6,000 / ($500 × 0.80) = $6,000 / $400 = 15 months

Shorter payback means cash comes back sooner and growth needs less funding. Work it out by channel as well as blended. Referral and organic customers often pay back far faster than paid search, and a blended figure can hide a channel that never pays back. The CAC calculator separates blended and paid CAC.

LTV:CAC

LTV = average MRR per customer × gross margin / monthly churn rate

With $500 a month, 80% margin and 2% monthly churn: $500 × 0.80 / 0.02 = $20,000.

LTV:CAC = $20,000 / $6,000 = about 3.3.

David Skok's widely used SaaS metrics guide puts a healthy ratio above 3. Below 1, each customer costs more than they bring in. Be careful with LTV: the formula assumes churn stays constant, and a young product often has too little history to know its real churn. Use gross margin, not revenue, and say which churn you used. The LTV calculator does the arithmetic.

The quick ratio

Quick ratio = (new + expansion + reactivation MRR) / (contraction + churned MRR)

For Company A above: $11,000 / $4,000 = 2.75. For Company B: $9,000 / $1,000 = 9. A commonly quoted target for early-stage SaaS is 4 or more: four dollars added for every dollar lost. Below 1, MRR is shrinking. Some definitions leave reactivation out, so say which one you use. The MRR calculator gives net new MRR, the quick ratio and monthly NRR from one month of movements.

What to review, and how often

Weekly: net new MRR and its components (new, expansion, contraction, churn), logos lost with names, pipeline for the month.

Monthly: NRR and GRR (trailing twelve months), logo and revenue churn, CAC payback by channel, the quick ratio.

Quarterly: NRR by segment, churn by cohort and by reason, LTV:CAC, expansion concentration.

Common mistakes

• Choosing the flattering number. Reporting NRR without GRR, or logo churn when revenue churn is worse.
• Ignoring contraction. Downgrades are churn in slow motion.
• Blending CAC across channels, which hides the channel that never pays back.
• Optimistic LTV from a few months of low early churn.
• No cohorts, so improvements and regressions in retention stay invisible.

Tracking these in clariBI

Most of these metrics start in the billing system. clariBI connects Stripe through the MCP catalog (from the trial up) and reads subscriptions, invoices, customers and payouts. PayPal is also in the catalog. Other billing systems such as Chargebee or Paddle have no connector, so use a CSV export. Once Stripe has synced, you can ask questions such as "What is MRR now, and how much of this month's change was new, expansion, contraction and churn?" or "Which plan has the highest churn over the last six months?". The answers are calculated with code from your Stripe rows. How edge cases such as annual plans or refunds are treated depends on how they appear in your data, so check the table under each answer. The SaaS use case lists the questions and sources that work well together, and the help article with 30 example questions shows how to phrase them.

On Starter and above, you can also forecast MRR with 50%, 80% and 95% ranges and see which other metrics (signups, ad spend) move with it.

Next step

Take last month's numbers and fill in five lines: starting MRR, new, expansion, contraction and churned. Put them into the MRR calculator. If the quick ratio comes out below 2, look at churn and contraction before spending more on acquisition.