SaaS Metrics Calculator — Rule of 40, LTV:CAC, NRR, Burn Multiple & Runway

How to Use the SaaS Metrics Calculator

1. Enter your beginning MRR — the monthly recurring revenue at the start of the period.
2. Fill in New, Expansion, Contraction, and Churned MRR for the month. These four line items drive NRR, GRR, and Quick Ratio.
3. Enter customer counts: beginning, new, and churned customers. This is used for ARPA, CAC, and customer churn rate.
4. Set your S&M spend (sales and marketing cost) for the month and your gross margin %. CAC and LTV depend on these.
5. Enter cash balance and monthly net burn to compute Runway.
6. For Rule of 40, enter your annualized MRR growth rate and your profit/FCF margin % (negative if you are loss-making).
7. All metrics update instantly and are color-coded green (healthy), yellow (caution), or red (action needed) based on SaaS benchmarks.

SaaS Metrics Glossary & Formulas

MRR (Monthly Recurring Revenue) is the normalized monthly revenue from all active subscriptions. Ending MRR = Beginning MRR + New MRR + Expansion MRR − Contraction MRR − Churned MRR. MRR is the heartbeat metric of any subscription business — it tells you exactly where the business stands each month and tracks growth precisely. ARR (Annual Recurring Revenue) is simply MRR multiplied by 12, used for investor reporting and company valuation.

NRR (Net Revenue Retention) measures what percentage of your beginning MRR you retained — including upsells and downgrades — over a period. Formula: NRR = (Beginning MRR + Expansion MRR − Contraction MRR − Churned MRR) / Beginning MRR × 100. An NRR above 100% means your existing customer base is growing even without any new customers — a hallmark of elite SaaS businesses. Best-in-class companies like Snowflake or Twilio have achieved NRR of 130%+ at scale.

GRR (Gross Revenue Retention) is the floor of NRR — it measures revenue retained from existing customers excluding any expansion. Formula: GRR = (Beginning MRR − Contraction MRR − Churned MRR) / Beginning MRR × 100. GRR can never exceed 100%. It reflects the stickiness of your core product. A GRR above 90% is excellent for most SaaS segments; enterprise products often achieve 95%+.

Revenue Churn Rate is the percentage of MRR lost from existing customers in a month, calculated as Churned MRR / Beginning MRR. This drives LTV calculations. Customer churn rate is the percentage of customers who cancelled: Churned Customers / Beginning Customers. Both should be tracked — they diverge when larger accounts churn disproportionately (or vice versa).

ARPA (Average Revenue Per Account) is MRR divided by total active customers. If you enter a manual ARPA override, that value is used; otherwise the calculator uses Beginning MRR / Beginning Customers. ARPA is the key lever for LTV and CAC Payback — increasing ARPA by pricing higher or selling richer packages accelerates payback time significantly.

CAC (Customer Acquisition Cost) is the total cost to acquire one new customer. Formula: CAC = S&M Spend / New Customers Acquired this month. This is a simplified single-period CAC; some companies use a lagged model. CAC by itself is meaningless — it must be compared to LTV. A $5,000 CAC is excellent if LTV is $50,000; it is catastrophic if LTV is $3,000.

LTV (Lifetime Value / Customer Lifetime Value) is the expected gross profit generated by a customer over their lifetime. Formula: LTV = (ARPA × Gross Margin %) / Monthly Revenue Churn Rate. This formula assumes steady-state churn and constant ARPA — a simplification, but the industry standard for early-stage modeling. Growing ARPA through expansion and reducing churn both compound to dramatically increase LTV.

LTV:CAC Ratio is the single most-cited SaaS unit economics benchmark. Benchmark: LTV:CAC ≥ 3× is healthy; ≥ 5× is excellent; < 1× means you are destroying value on every customer acquired. Many venture-backed companies intentionally run a low LTV:CAC in early stages while investing aggressively in growth, expecting to improve it at scale.

CAC Payback Period is the number of months to recover the CAC from gross profit. Formula: CAC Payback = CAC / (ARPA × Gross Margin %). Benchmark: under 12 months is excellent for SMB SaaS; 12–24 months is typical for mid-market; 24–36 months can be acceptable for enterprise with high NRR. The shorter the payback, the faster each new customer starts contributing net cash flow.

Rule of 40 balances growth rate and profitability — the insight being that a high-growth company can be forgiven for losses (they are investing in the future), while a slow-growth company must be profitable. Rule of 40 = Annual ARR Growth % + Profit/FCF Margin %. A score of 40%+ is the industry benchmark for a healthy SaaS business; scores above 60–70% are elite. Below 20% signals a company that is neither growing fast nor profitable.

Burn Multiple (coined by David Sacks) measures how efficiently a company converts burn into net new ARR. Formula: Burn Multiple = Net Burn / Net New ARR (annualized). Net New ARR = (Ending MRR − Beginning MRR) × 12. Benchmark: under 1× is excellent; 1–1.5× is good; above 2× is concerning; above 2× at scale is a red flag. High burn multiples mean you are spending a lot relative to the growth you are generating.

Quick Ratio (also called the SaaS Magic Number variant) measures the quality of MRR growth. Formula: Quick Ratio = (New MRR + Expansion MRR) / (Churned MRR + Contraction MRR). A Quick Ratio above 4 is excellent — you are adding far more revenue than you are losing. A Quick Ratio below 1 means the company is shrinking. This metric reveals whether growth is masking a churn problem.

Runway is the number of months a company can operate at its current net burn rate before running out of cash. Formula: Runway = Cash Balance / Monthly Net Burn. Benchmark: under 6 months is a fundraising emergency; 6–12 months is tight; 12–18 months is a standard raise signal; 18–24+ months is comfortable. Smart founders start fundraising at 12+ months of runway to negotiate from strength, not desperation.

Color-Coded Health Score Benchmarks

This calculator uses three health signal colors: green (healthy, meeting or exceeding benchmark), yellow (caution, approaching threshold), and red (action needed, below acceptable range). Here are the thresholds used for each metric:

• NRR: ≥100% green, 90–100% yellow, <90% red
• GRR: ≥90% green, 80–90% yellow, <80% red
• Revenue Churn: ≤1% green, 1–2% yellow, >2% red (monthly)
• Customer Churn: ≤2% green, 2–4% yellow, >4% red (monthly)
• LTV:CAC: ≥3× green, 1–3× yellow, <1× red
• CAC Payback: <12mo green, 12–24mo yellow, >24mo red
• Rule of 40: ≥40 green, 20–40 yellow, <20 red
• Burn Multiple: ≤1× green, 1–2× yellow, >2× red
• Quick Ratio: ≥4 green, 2–4 yellow, <2 red
• Runway: ≥18mo green, 6–18mo yellow, <6mo red

Frequently Asked Questions

• What is a good NRR for a SaaS company?
  Net Revenue Retention above 100% is the gold standard — it means your existing customer base grows without any new sales. For product-led growth companies, 100–110% is solid. For enterprise SaaS, 120%+ is achievable and expected. B2B SaaS companies that achieve IPO typically have NRR above 110–120%. If your NRR is below 90%, churn is actively destroying value faster than expansion can compensate, and this must be fixed before scaling.
• What is the Rule of 40 and why does it matter?
  The Rule of 40 combines annual growth rate and profit margin into a single efficiency score. A company growing at 50% but burning 15% of revenue scores 35 — just below the threshold. A company growing at 25% but profitable at 20% scores 45 — above threshold. It matters because it prevents over-optimizing for one dimension: growth without any path to profitability, or profitability at the cost of stagnation. Most SaaS investors use Rule of 40 as a quick filter for valuation multiples — companies above 40 tend to command premium ARR multiples.
• What is Burn Multiple and how is it different from burn rate?
  Burn rate is simply how much cash you spend each month. Burn Multiple contextualizes burn against what you are getting for it in terms of new ARR. If you are burning $500K/month and generating $250K in net new ARR/month ($3M annualized), your burn multiple is $500K / $250K = 2×. This is a warning sign. A burn multiple of 0.5× would mean you are generating twice as much new ARR as you are burning — extremely capital efficient. Burn multiple is especially useful for comparing companies of different sizes and growth stages.
• Why is LTV often understated by simple formulas?
  The standard LTV formula assumes constant ARPA and constant churn — both of which are rarely true. In practice, customers who stay longer often expand their usage (increasing ARPA), and the customer cohort that survives past 12 months tends to churn at a lower rate than new cohorts. Both factors mean true LTV is usually higher than the simple formula suggests. For fundraising and strategic decisions, consider building cohort analysis that tracks actual LTV over time rather than relying solely on steady-state formulas.
• How much runway should a SaaS startup maintain?
  The general rule is 18–24 months of runway at all times for a venture-backed startup. This ensures you have enough time to hit milestones before your next raise, and enough buffer to negotiate from strength rather than desperation. Below 12 months, you should be actively in fundraising conversations. Below 6 months, you are in crisis mode — investors can smell distress, and terms deteriorate. If you are profitable or near-profitable, runway becomes less critical since you control your own destiny.
• How is CAC Payback different from LTV:CAC?
  LTV:CAC is a ratio of total expected value to acquisition cost — it tells you the long-run return on customer acquisition. CAC Payback is an operational metric that tells you how quickly you get your money back. A company might have a great 5× LTV:CAC but a 30-month payback if ARPA is low — meaning cash is tied up for years before each customer turns cash-flow positive. For companies with limited cash, short payback periods matter as much as high LTV:CAC ratios. Ideally, you want both: high LTV:CAC and short payback.