SaaS MRR Forecast Calculator (Growth, Churn and Expansion)
Enter MRR, new sales, churn and expansion to forecast revenue.
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SaaS MRR Forecast Calculator (Growth, Churn and Expansion) by TheCalcTools
How the SaaS MRR Forecast Calculator (Growth, Churn and Expansion) works
Each month the existing MRR changes by expansion minus churn, and new MRR is added: M(n+1) = M(n) × (1 − churn + expansion) + new.
This closed form gives MRR at any month and the total revenue over 12 months.
If churn exceeds expansion, MRR levels off at new ÷ net churn.
The formula
Worked example
Using the default values shown in the calculator:
| Starting MRR | $10000 |
|---|---|
| New MRR added each month | $1500 |
| Monthly revenue churn | 3 % |
| Monthly expansion of existing MRR | 1 % |
| Months to forecast | 12 |
- Starting at $10,000 with $1,500 new MRR a month, 3% churn and 1% expansion, g = 0.98.
- After 12 months MRR is $23,993; after 24 months $34,974. Revenue in year one is $214,323. Steady state: $75000.
Result:
| MRR after the chosen months | $23,993 |
|---|---|
| ARR at that point | $287,921 |
| MRR after 6 months | $17,420 |
| MRR after 12 months | $23,993 |
| MRR after 24 months | $34,974 |
| Revenue collected in the first 12 months | $214,323 |
| Net monthly growth rate on existing MRR | -2.0% |
| Steady-state MRR (new ÷ net churn) | $75000 |
Frequently asked questions
What is a good monthly churn rate?
For small SaaS businesses 3% to 7% a month is common; larger companies aim for 1% or less.
Why does MRR level off?
When churn is higher than expansion, the lost revenue each month eventually equals the new revenue you add, and growth stops.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.