SaaS Metrics Calculator
Compute MRR, ARR, NRR, GRR, LTV, CAC, Quick Ratio, Magic Number and Rule of 40.
Overview
A SaaS metrics calculator turns raw subscription and customer data into the standard set of operating numbers that boards, investors, and operators expect to see: monthly recurring revenue (MRR), annual recurring revenue (ARR), net and gross revenue retention (NRR, GRR), customer lifetime value (LTV), customer acquisition cost (CAC), the Quick Ratio, the Sales Efficiency Magic Number, and the Rule of 40. Each metric isolates a different question — growth quality, retention strength, unit economics, and the trade-off between growth and profitability.
These metrics evolved out of public SaaS reporting in the 2010s and are now the lingua franca for fundraising decks, board reports, and analyst models. Computing them consistently is harder than it looks because every definition has edge cases (annual prepayments, multi-product customers, contract terms, discounts) and different vendors choose different conventions. This tool applies the most common SaaS conventions — Bessemer, OpenView, and SaaStr definitions — so the numbers map cleanly to industry benchmarks.
How it works
MRR = sum of contracted monthly subscription revenue. ARR = MRR × 12. NRR = (starting MRR + expansion − contraction − churn) / starting MRR. GRR = (starting MRR − contraction − churn) / starting MRR, capped at 100%. LTV = ARPU × Gross Margin / Churn Rate. CAC = sales & marketing spend / new customers acquired. Quick Ratio = (new MRR + expansion MRR) / (contraction MRR + churn MRR). Magic Number = (current Q ARR − prior Q ARR) × 4 / prior Q S&M. Rule of 40 = revenue growth % + free cash flow margin %.
Examples
- Starting MRR $100k, expansion $10k, contraction $2k, churn $3k → NRR
(100 + 10 − 2 − 3)/100 = 105%, GRR(100 − 2 − 3)/100 = 95%— best-in-class retention. - ARPU $100/month, 80% gross margin, monthly churn 2% → LTV =
100 × 0.8 / 0.02 = $4,000. CAC of $1,000 gives LTV:CAC = 4.0 — investable. - New MRR $20k + expansion $5k versus contraction $3k + churn $4k → Quick Ratio =
25/7 ≈ 3.6— strong growth. - 40% revenue growth and −10% FCF margin → Rule of 40 = 30. Below the 40 threshold but defensible if growth is high quality.
FAQ
Why is NRR the headline retention metric?
NRR captures both stickiness and the ability to expand existing accounts. Above 100% means the existing base alone is growing.
What's a good Magic Number?
Above 0.75 generally means efficient sales spend; above 1.0 is excellent. Below 0.5 signals overspend on go-to-market.
Should I use gross or net MRR for churn?
Gross churn (logos or revenue lost) for GRR; net churn (after expansion) for NRR.
How do I treat annual prepayments?
Spread them across 12 months for MRR/ARR. For cash flow reporting, keep the lump-sum receipt visible.
Is the Rule of 40 still relevant at smaller scale?
The thresholds shift below ~$10M ARR — growth tends to dominate, and negative FCF is normal.