Calculate MRR, ARR, churn rate, expansion revenue, LTV, CAC payback, and quick ratio from subscription business inputs.
Subscription revenue is easy to misread because churn and expansion are both dollars pulling in opposite directions. This calculator takes your starting MRR for a month plus new, expansion, churned, and downgraded revenue, and derives the standard SaaS metrics: ending MRR, ARR, gross and net revenue churn, LTV, CAC payback, and quick ratio. What surprises people most: gross revenue churn can be positive while net revenue churn is negative, meaning expansion from existing customers more than pays for losses. The business loses revenue and grows in the same month.
A concrete input and expected output from the current implementation.
Input
Starting MRR: $100,000 | New MRR: $12,000 | Expansion MRR: $3,000 | Churned MRR: $6,000 | Contraction MRR: $2,000
Expected output
Ending MRR: $107,000 | Net new MRR: $7,000 (7.0% month-over-month growth) | Gross revenue churn: 8.0% | Net revenue churn: 5.0% | Quick ratio: 1.88 | ARR: $1,284,000
Ending MRR is the waterfall 100,000 + 12,000 + 3,000 - 6,000 - 2,000 = 107,000. The quick ratio divides growth (12,000 + 3,000 = 15,000) by losses (6,000 + 2,000 = 8,000), giving 1.875, and ARR is ending MRR times 12. Net revenue churn (5.0%) is below gross churn (8.0%) because expansion recovered 3.0% of starting MRR.
The core month is built as a waterfall: ending MRR equals starting MRR plus new-customer MRR plus expansion MRR minus churned MRR minus contraction MRR. From that it derives ARR as ending MRR times 12, month-over-month growth as net new MRR divided by starting MRR, and gross and net revenue churn from the same loss and expansion figures, all against starting MRR as the denominator.
LTV is ARPA times gross margin divided by the monthly revenue churn rate. CAC payback is acquisition cost divided by monthly gross profit per account, which is ARPA times gross margin. Both therefore depend on three inputs beyond the MRR waterfall: average revenue per account, gross margin percent, and the monthly churn rate, so they are only as reliable as those assumptions.
No. This tool measures revenue churn: MRR lost to cancellations and downgrades divided by starting MRR. Customer (logo) churn counts accounts instead, and the two diverge whenever the customers who leave pay more or less than the average. Funding and board conversations usually quote revenue-based figures, but confirm which one is actually being asked for.
A quick ratio above 1 means new and expansion MRR exceed what churn and contraction take away, so the base is growing. Many investors treat 4 or higher as strong for early-stage SaaS, but the benchmark depends on growth stage and pricing model, and a single month's figure is noisy. Read it as a trend across several months rather than judging one run.
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