MRR Churn Math Every SaaS Founder Must Know

The Core MRR Equation

Every month, your MRR moves by a simple equation: New MRR = Starting MRR + New + Expansion − Churned − Contracted. Growth feels like a function of sales, but churn is the silent term that compounds against you. Model it with our MRR Growth Projector to see the curve.

Why Small Churn Differences Are Enormous

At 2% monthly logo churn, the average customer lasts 50 months. At 5%, they last 20 months. That 3-point gap more than halves customer lifetime value — and therefore halves what you can afford to spend on acquisition. Churn is leverage in reverse.

Worked example: $50k MRR, 8% monthly growth from new sales, 4% monthly churn. Net growth is roughly 4% — but you are re-selling nearly half your new revenue every month just to stand still. Cut churn to 2% and net growth doubles without a single extra sale.

Logo Churn vs Revenue Churn

Logo churn counts customers lost; revenue churn counts dollars lost. They diverge when expansion revenue exists: you can lose 3% of logos monthly yet grow revenue if remaining accounts expand. Best-in-class SaaS companies run negative net revenue churn — the installed base grows on its own.

• Track both monthly; report net revenue retention to investors.
• Segment churn by cohort, plan tier, and acquisition channel.
• Attack early-life churn first — the first 90 days dominate lifetime churn.

Connecting Churn to Valuation

Revenue multiples expand as net retention rises because predictable, compounding revenue is worth more. A company at 120% net retention can command a meaningfully higher multiple than an identical-revenue peer at 95%. Sanity-check the output with our Startup Valuation Calculator and our Churn Rate Calculator.

Bottom Line

Growth gets the headlines; churn decides the outcome. Run your numbers in the MRR Growth Projector, then put one initiative per quarter against your biggest churn segment.