4/4+150 XP

The five calculations every SaaS professional runs

A CFO says on a call: "We're at $2.1M MRR, growing 8% month over month, burning $600K a month." In the next ten seconds, everyone competent on that call has silently done three calculations and formed a view on whether the business is healthy. If you can't do that math in real time, you're not in the conversation, you're just listening to it.

This lesson gives you those five calculations, cold. MRR stands for Monthly Recurring Revenue: the predictable subscription revenue a company collects each month, excluding one-time fees.

Calculation 1: annualizing MRR into ARR

ARR (Annual Recurring Revenue) is simply MRR times 12. It's the headline number every SaaS company reports.

Worked example: MRR = $2.1M → ARR = $2.1M × 12 = $25.2M.

Watch for the trap: ARR is a run-rate snapshot, not cash actually collected over a year. If a company signed a big customer last week, ARR jumps immediately even though only days of revenue exist. Always ask "as of when?"

Calculation 2: Sanity-checking a growth claim

Growth rate claims get thrown around loosely ("we grew 8% last month," "we're up 3x year over year"). The professional move is converting monthly growth into annualized terms to compare against benchmarks, because compounding is not intuitive.

Formula: (1 + monthly growth rate)^12 − 1

Worked example: 8% month-over-month compounds to (1.08)^12 − 1 ≈ 152% annualized growth. That's a very different story than "8%" sounds like in a sentence, and it should make you ask whether that rate is sustainable or driven by one lumpy deal.

As of 2025 to 2026, benchmark reports (see OpenView's SaaS Benchmarks, free annual survey) put median annual growth for SaaS companies under $10M ARR at roughly 60 to 100% (estimate, varies by cohort and year), decelerating to 20 to 30% (estimate) above $50M ARR. If someone claims 150%+ sustained growth at scale, that's a flag to probe, not applaud.

Calculation 3: the rule of 40

This is the single most quoted SaaS health check. It says growth rate (%) plus profit margin (%) should be at least 40.

Formula: Revenue growth rate + EBITDA margin (or free cash flow margin) ≥ 40%

EBITDA: Earnings Before Interest, Taxes, Depreciation and Amortization, a proxy for operating profitability.

Worked example: A company growing ARR at 30% with a -5% EBITDA margin scores 25. Below 40, meaning investors would want to see either faster growth or less burn. A company growing at 20% with a +25% margin scores 45. Healthier, even though growth looks slower.

The Rule of 40 became popular via public SaaS investors and is referenced constantly in board decks. It's a heuristic, not gospel. Early-stage companies (under ~$5M ARR) are usually exempt in practice because the growth side dominates and margins are expected to be negative.

Calculation 4: Burn multiple

Burn multiple tells you how much cash a company burns to generate each new dollar of ARR. It's become the preferred efficiency metric since the 2022 rate-driven shift toward capital discipline.

Formula: Net Burn ÷ Net New ARR (over the same period)

Worked example (continuing our CFO's numbers): Net burn = $600K/month. Say net new ARR added that month = $200K (i.e., MRR grew by roughly $17K, extrapolate to net new ARR added in the period, or use quarterly figures for less noise). Burn multiple = $600K ÷ $200K = 3.0x.

Benchmark (per investor Bessemer Venture Partners, whose burn multiple framework is now industry standard, see their State of the Cloud reports): under 1x is excellent, 1 to 1.5x is good, above 2x is inefficient and above 3x is a red flag at scale. Our example CFO's business, burning 3x, would face hard questions in a board meeting or a fundraise.

Calculation 5: CAC payback and the rule of 3 (LTV:CAC)

CAC: Customer Acquisition Cost, the fully loaded sales and marketing spend to acquire one new paying customer. LTV: Lifetime Value, the total gross profit expected from a customer over their relationship with you.

CAC payback = CAC ÷ (Monthly revenue per customer × gross margin %). This tells you how many months it takes to earn back what you spent acquiring the customer.

Worked example: CAC = $3,000. Customer pays $250/month, gross margin = 80%. Monthly gross profit per customer = $200. Payback = $3,000 ÷ $200 = 15 months.

Benchmark: under 12 months is strong for SaaS, 12 to 18 is workable, over 24 months strains cash flow (estimates, vary heavily by segment; enterprise SaaS tolerates longer paybacks than SMB-focused SaaS).

The companion check is LTV:CAC ratio, commonly cited target is 3:1 or higher (LTV at least three times CAC). Below 3:1, the unit economics likely can't support current spending once you account for churn and operating costs.

Knowledge check

1. A company's ARR jumped significantly this week because a large customer just signed. What is the most important caveat to keep in mind when interpreting this new ARR figure?

2. Why is simply multiplying a monthly growth rate by 12 the wrong way to estimate annualized growth?

3. A founder says their SaaS company is growing at 150% annualized while at $80M ARR. Based on typical SaaS growth benchmarks, how should this claim be treated?

MULTIPLE CHOICE

4. Select ALL correct answers about the relationship between MRR and ARR.

Select all the correct answers.

MULTIPLE CHOICE

5. Select ALL correct answers about why professionals convert monthly growth rates into annualized figures.

Select all the correct answers.

Putting it together: reading a company in one pass

Back to our CFO. ARR ≈ $25.2M. Annualized growth ≈ 150%+ if the 8% monthly pace holds (unlikely to be sustained, worth probing). Burn multiple = 3.0x (inefficient by Bessemer's framework). Rule of 40: even at a generous 100% blended growth estimate and a heavily negative margin from that burn rate, you'd need to see the actual margin number to score it properly, but a 3x burn multiple at $25M ARR usually implies a Rule of 40 score well under 40.

The read: fast-growing, but currently inefficient. Not a red flag in isolation (early scale-ups often look like this), but a real question for the next round: does efficiency improve as they approach $50M ARR, or is this structural?

A quick due-diligence habit

When someone shows you SaaS numbers, run this sequence in under a minute:

Confirm the MRR/ARR figure and its "as of" date.
Annualize any growth rate quoted monthly, don't compare monthly and annual figures directly.
Compute Rule of 40 if margin data is available.
Compute burn multiple if cash burn is disclosed.
Ask for CAC and gross margin to get payback period, the number most often omitted because it's the least flattering.

For US and Europe context: as of 2025 to 2026 estimates, the US SaaS market remains roughly 2 to 3 times the size of Europe's by revenue (commonly cited industry estimate, exact figures vary by source and definition), and European SaaS companies typically report lower CAC and slower but steadier growth than US peers, partly due to smaller domestic markets forcing earlier multi-country expansion and more capital-efficient habits.

🎬 [VIDEO: "SaaS Metrics 101" - youtube.com - search for Bessemer Venture Partners or a16z SaaS metrics explainer walking through Rule of 40, burn multiple, and CAC payback with real investor framing]

Key Takeaways

ARR = MRR × 12, but always ask "as of when," it's a snapshot, not cash collected.
Annualize monthly growth rates before comparing them to benchmarks: (1+monthly rate)^12 − 1, compounding is easy to underestimate.
Rule of 40 (growth % + margin % ≥ 40) and burn multiple (net burn ÷ net new ARR, under 1.5x is good, over 3x is a flag) are the two fastest efficiency checks.
CAC payback under 12 to 18 months and LTV:CAC above 3:1 are the standard unit-economics thresholds; ask for gross margin, not just revenue, when computing these.
Treat every benchmark here as a directional estimate that varies by company stage, segment (SMB vs enterprise) and region (US vs Europe); the calculation matters more than memorizing one "correct" number.

Benchmarks that separate good from great