Rule of 40

What is the Rule of 40?

The Rule of 40 (also called the 40% rule, Ro40, or growth-profitability index) is a heuristic used by SaaS investors and operators to evaluate whether a company is balancing growth and efficiency. The formula is simple: year-over-year revenue growth rate + EBITDA margin (or FCF margin). The combined score should be 40 or higher.

The Rule of 40 exists because growth and profitability trade off against each other. A company can grow 80% by spending aggressively and running -30% EBITDA margin (score: 50). A company can grow 10% but achieve 35% EBITDA margin (score: 45). Both clear the threshold. The Rule of 40 doesn't prescribe the mix — it validates the balance.

For B2B SaaS between $5M and $50M ARR, the Rule of 40 serves as a north star for operating decisions. Should we hire 5 more reps this quarter? If the incremental growth doesn't offset the margin impact enough to maintain a 40+ score, the hiring plan needs rethinking.

The Rule of 40 is not perfect. It treats a 1-point growth increase the same as a 1-point margin increase — but growth compounds while margin doesn't. A company scoring 50 through 45% growth and 5% margin is more valuable than one scoring 50 through 10% growth and 40% margin. The rule is directionally useful, not precisely calibrated.

Why the Rule of 40 matters for operators

The Rule of 40 provides a shared language between operators, boards, and investors. When the CEO asks "should we invest in growth or profitability this quarter?", the Rule of 40 frames the answer: whichever move keeps or improves the combined score.

Operators who track the Rule of 40 quarterly make better resource allocation decisions. If the score is 30 and growth is 18%, the lever to pull is profitability — cut spend that isn't generating revenue. If the score is 30 and margin is already 25%, the issue is growth — the company needs more efficient acquisition channels or product-led growth.

The Rule of 40 also signals fundraising readiness. Companies consistently above 40 command higher valuation multiples. Bessemer data shows that public SaaS companies scoring above 40 trade at 2-3x higher EV/revenue multiples than those scoring below 20. For private companies, the same pattern holds in fundraising.

Rule of 40 formula

Rule of 40 Score = Revenue Growth Rate (%) + EBITDA Margin (%)

Example 1: Growth-stage company
- YoY revenue growth: 55%
- EBITDA margin: -12%

Score = 55 + (-12) = 43 ✓ Above 40

Example 2: Mature company
- YoY revenue growth: 18%
- EBITDA margin: 28%

Score = 18 + 28 = 46 ✓ Above 40

Example 3: Struggling company
- YoY revenue growth: 22%
- EBITDA margin: 8%

Score = 22 + 8 = 30 ✗ Below 40

Variant — using FCF margin instead of EBITDA:

Rule of 40 (FCF) = Revenue Growth Rate (%) + FCF Margin (%)

FCF Margin = Free Cash Flow / Revenue x 100

Some investors prefer FCF margin because it includes CapEx
and working capital changes that EBITDA ignores.

Rule of 40 benchmarks

How SaaS companies score against the Rule of 40 at different stages.

Sources: Bessemer State of the Cloud 2025, KeyBanc SaaS Survey 2025, SaaStr 2025 Benchmark Report.

Common mistakes with the Rule of 40

1. Applying it to pre-product-market-fit companies

The Rule of 40 assumes the company has a repeatable growth engine. A seed-stage company growing 200% from $200K to $600K ARR doesn't need this benchmark. The Rule of 40 becomes meaningful after $5M ARR when growth is no longer driven by a single founder's network.

2. Treating growth and margin as equally valuable

A company at 45% growth / -5% margin (score: 40) is typically more valuable than one at 5% growth / 35% margin (score: 40). Growth compounds. Margin doesn't. The Rule of 40 treats them as interchangeable — but investors don't. Weight growth more heavily in your own analysis.

3. Measuring growth on a quarterly basis only

Year-over-year growth smooths seasonality. Quarter-over-quarter growth is more volatile and can overstate performance in strong quarters. Use YoY for the Rule of 40 calculation. Track QoQ growth separately for operational monitoring.

4. Ignoring the trajectory

A company scoring 35 with an improving trend (from 25 last year) is in a better position than one scoring 38 with a declining trend (from 48 last year). The score matters, but the direction matters more. A declining Ro40 score over 3+ quarters signals structural deterioration.

How Fairview tracks the Rule of 40 automatically

Fairview's Margin Intelligence calculates the Rule of 40 score automatically by connecting ARR growth data from your CRM with EBITDA data from your accounting platform. The score is updated monthly and displayed alongside the component breakdown.

The Operating Dashboard shows the Rule of 40 trended over time with a drill-down into what's driving changes — growth rate shifts, margin changes, or both. When the score drops below the target threshold, the Next-Best Action Engine identifies the lever: "Ro40 score dropped from 42 to 34. Growth rate declined 6 points while margin was flat. Review pipeline generation and conversion."

→ See how Margin Intelligence works

Rule of 40 vs burn multiple

The Rule of 40 is a scorecard — it tells you whether the company is balanced. Burn multiple is a speedometer — it tells you whether the growth engine is consuming cash efficiently. Use both: Rule of 40 for strategic direction, burn multiple for operational efficiency.

FAQ

What is the Rule of 40 in simple terms?

The Rule of 40 says a SaaS company's growth rate plus profit margin should add up to at least 40%. If you're growing 50% per year, you can afford to lose 10% in margins and still score 40. If you're growing 15%, you need 25% margins to make up the difference. It balances speed against sustainability.

What is a good Rule of 40 score?

Above 40 is the target — it signals a healthy balance of growth and efficiency. Above 50 is strong. Above 60 is exceptional (typically high-growth companies with improving margins). Below 30 for more than 2 quarters signals a structural problem. The median public SaaS company scores around 32.

How do you calculate the Rule of 40?

Add your year-over-year revenue growth rate (as a percentage) to your EBITDA margin (as a percentage). If revenue grew 35% and EBITDA margin is 12%, your score is 47. Negative margins subtract from the score — 35% growth with -15% margin scores 20.

Does the Rule of 40 apply to non-SaaS companies?

The Rule of 40 was designed for subscription SaaS with recurring revenue. It can be adapted for subscription-adjacent models (D2C subscription, membership businesses) but is less meaningful for transactional businesses where revenue doesn't recur. The "40" threshold is SaaS-specific.

How often should you measure the Rule of 40?

Quarterly is the standard cadence. The growth rate component should be measured year-over-year to avoid seasonal distortion. The margin component can be measured on a trailing-12-month basis for stability. Report the score to the board quarterly alongside the trajectory.

Can the Rule of 40 score be too high?

Rarely, but a score above 70 could indicate underinvestment. If the score comes from 15% growth and 55% margin, the company might be sacrificing growth for profitability. At that margin level, it should be able to invest more in growth while keeping the score above 40. Extremely high scores warrant a growth investment discussion.

Related terms

• EBITDA — The profitability component of the Rule of 40
• ARR (Annual Recurring Revenue) — Revenue base used to calculate the growth component
• Burn Multiple — Cash efficiency metric, operational complement to Rule of 40
• Gross Margin — Product-level profitability, a prerequisite for strong EBITDA margin
• NRR (Net Revenue Retention) — High NRR supports both growth rate and margin simultaneously

Fairview is an operating intelligence platform that tracks the Rule of 40 automatically — alongside EBITDA, burn multiple, and ARR growth. Start your free trial →

Siddharth Gangal is the founder of Fairview. He built Rule of 40 tracking into the platform because operators were making growth-vs-profitability tradeoffs without a shared framework to evaluate them.