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SaaS MRR / ARR Calculator
Project MRR, churn and LTV.
How this tool works
MRR (Monthly Recurring Revenue) is the king metric in SaaS. But MRR alone tells you nothing — what matters is the combination of growth rate, churn and ARPU. A company with 20% growth and 5% churn is growing 15% net. Another with 30% growth and 20% churn is broken even if absolute numbers go up.
This calculator models your SaaS month by month over 12-36 months. Applies churn to existing MRR, adds new customers at the growth rate you set, and returns LTV (lifetime value of an average customer) and CAC payback (months to recover acquisition cost). Ideal for investor decks, annual planning and benchmarking.
Formula
MRR_n = MRR_{n-1} × (1 − churn) + new_n × ARPU. LTV = ARPU / monthly churn. CAC payback = CAC / (ARPU × margin).
Frequently asked questions
- What churn is acceptable?
- Healthy B2B SaaS: 1–3% monthly. B2C: 5–7%. If you exceed 10%, your product isn't retaining — fix that first, don't spend on growth.
- How do I calculate LTV?
- LTV = ARPU / monthly churn. If ARPU is $50 and churn 3%, LTV = $50/0.03 = $1,667. Multiply by gross margin for net LTV.
- What CAC payback is good?
- Bottom-up SaaS: 5–7 months. Mid-market: 12 months. Enterprise: 18-24 months. Beyond 24 months, you'll never be profitable.
- What about upgrades/downgrades?
- This calc assumes constant ARPU. For advanced modeling, separate expansion MRR (upgrades) from new MRR. Net Revenue Retention >100% (NRR) means you charge existing customers more than you lose to churn — best-in-class SaaS has NRR 120%+.