MRR & Churn Forecaster (2026)
Project subscription revenue month by month, gross churn, expansion, and net-new bookings on one interactive curve.
100% client-side. Your inputs stay in this browser.
Stress-test monthly churn, expansion, and net-new bookings, see where MRR lands and how much growth churn silently taxes.
MRR at horizon
$109,907
ARR at horizon
$1,318,883
Annualized factor
69.4%
(1 − churn + expansion)12
ARR gap vs no-churn path
$1,061,366
(No-churn MRR minus modeled MRR) × 12 at the horizon.
At 4% gross churn, you leave about $1,061,366 of annual revenue on the table vs. the same expansion and net-new with zero gross churn (terminal-month comparison).
MRR trajectory
Carry-forward vs net-new MRR
Each month's ending MRR stacked into surviving revenue (after churn + expansion) vs fresh bookings.
How this tool works
The forecast starts with your current MRR and applies four forces each month: existing MRR carries forward reduced by gross churn, expansion revenue adds from upsells and seat growth, net-new MRR arrives from new customers, and the result becomes the next month's starting balance. The formula per month: End MRR = Start MRR x (1 - gross churn) x (1 + expansion rate) + new MRR. Annualized NRR = (1 - gross churn + expansion rate) ^ 12. An NRR above 100% means existing customers generate more revenue each year without any new sales. The growth ceiling is the first month where churned MRR equals new MRR, at which point net growth stalls. A zero-churn overlay line shows the exact revenue you lose to compounding churn over the forecast horizon.
Worked example
Current MRR $50,000. New MRR per month $5,000. Gross churn 4%. Expansion 1%. Month 1: start $50,000, churned $2,000, after expansion $48,480, plus new MRR = $53,480. Month 12: MRR reaches approximately $94,000. Month 24: approximately $150,000. NRR = 0.97^12 = 69%, meaning the existing base shrinks 31% per year in revenue terms. Toggling the zero-churn overlay shows $170,000 by month 24. The $20,000 gap is the compounding cost of 4% monthly churn.
Frequently asked questions
What is a healthy monthly churn rate for SaaS?
For SMB SaaS products, 3 to 5% monthly gross churn is common. For mid-market and enterprise products with annual contracts, 0.5 to 1.5% is more typical. If your monthly churn exceeds 5%, the forecast will show a flattening curve because churn outpaces growth quickly.
What is the difference between gross churn and net churn?
Gross churn counts only lost revenue from cancellations and downgrades. Net churn subtracts expansion revenue from that number. This tool uses gross churn and expansion as separate inputs so you can see each force independently. Net churn = gross churn minus expansion rate. Use this metric consistently over time to track improvement rather than optimizing for a single period's snapshot.
What does NRR above 100% mean?
An NRR above 100% means your existing customers are spending more each year than they spent the year before, even without counting new customers. This happens when expansion revenue from upsells and seat growth exceeds churn losses. Top SaaS companies often target NRR of 110 to 130%.
Why does my forecast plateau?
The curve flattens when the dollars churned each month equal the new MRR added. At that point, you need to either reduce churn, increase new MRR, or grow expansion revenue to resume upward growth. The tool marks this month with a growth ceiling annotation.
Does the cohort toggle change the calculation?
Yes. The simplified default applies churn to the entire MRR base. The cohort toggle applies churn only to MRR that existed at the start of each month, not to net-new MRR added that same month. The cohort approach is slightly more accurate for businesses where new customers have a grace period before churn risk kicks in.
How should I set the expansion rate?
Look at your last 3 to 6 months of expansion MRR from upsells, add-ons, and seat increases, then divide by starting MRR for those months. If your product has no upsell path, set this to 0%. Including expansion when it does not exist will inflate your forecast.