SaaS MRR Growth Simulator: ARR, Churn, NRR, Quick Ratio

Model recurring revenue growth, Net Revenue Retention (NRR > 100%), logo vs revenue churn, and a 12-month valuation trajectory.

MRR, churn, NRR and Quick ratio: modelling SaaS growth

MRR grows each month by new MRR plus expansion, minus MRR lost to churn. Net revenue retention (NRR) compares the MRR kept from the existing base, expansion included, with starting MRR: above 100%, existing customers alone grow revenue. The tool projects this over 12 months.

Formulas used

  • ARPU = MRR ÷ active customers; new MRR = new customers per month × ARPU.
  • Churned MRR = customers × monthly churn, rounded to a whole customer, × ARPU; expansion = MRR × expansion rate.
  • NRR = (MRR + expansion − churned MRR) ÷ MRR.
  • Quick ratio = (new MRR + expansion) ÷ churned MRR.
  • LTV = ARPU × (100 ÷ churn %); LTV/CAC = LTV ÷ CAC.
  • Projection: each month, expansion applies to simulated MRR and churn to the simulated customer count.

The tool’s bands: NRR of 110% or more, excellent; 100% or more, healthy; below, erosion. Quick ratio of 4 or more, hypergrowth; under 2, churn too high. Indicative monthly churn: under 1% for enterprise B2B, 2-4% mid-market, over 5% B2C.

Example (default values)

€10,000 MRR, 100 customers, 15 new customers a month, 3.5% churn, 4% expansion, €350 CAC. ARPU: €100. New MRR: €1,500; 4 customers lost, i.e. €400; expansion: €400. NRR: 100.0%. Quick ratio: 1,900 ÷ 400 = 4.75. Lifetime: 28.6 months, LTV: €2,857, LTV/CAC: 8.2. After 12 months, MRR reaches €30,505 (ARR €366,060) with 214 customers.

Limits

  • New and churned customers stay valued at the starting ARPU, while expansion compounds monthly.
  • LTV ignores gross margin: it is based on revenue.
  • Churn is rounded to whole customers: 3.5% of 100 counts as 4.

This simulator tracks the recurring revenue trajectory; sales spend efficiency belongs to the Magic Number and CAC payback calculator, and cash autonomy to the runway calculator. Projections are indicative.

Frequently Asked Questions

How do you calculate net revenue retention (NRR)?

NRR = (starting MRR + expansion − MRR lost to churn) ÷ starting MRR. With €10,000 MRR, €400 of expansion and €400 of churn, NRR is 100%; the tool rates 110% and above as excellent.

What is the SaaS Quick ratio?

It is MRR gained (new customers plus expansion) divided by MRR lost. €1,500 of new MRR and €400 of expansion against €400 of churn give 4.75; the tool calls 4 and above hypergrowth and under 2 too much churn.

How do you calculate SaaS customer LTV?

The tool divides 100 by monthly churn in percent to get the average lifetime, then multiplies by ARPU. With 3.5% churn and €100 ARPU: 28.6 months and €2,857 LTV, 8.2 times a €350 CAC. This LTV is revenue-based, with no gross margin.

What monthly churn rate is normal for SaaS?

The tool’s benchmarks are indicative: under 1% a month for enterprise B2B, 2-4% mid-market and over 5% for B2C. At 3.5% a month, a base of 100 customers loses 4 in the month.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.