Rule of 40
Composite SaaS health score that sums the company's revenue growth rate and a profitability proxy (commonly EBITDA margin or free-cash-flow margin) into a single percentage. Originally articulated by Brad Feld in 2015 and codified by the SaaS Metrics Standards Board, the rule frames the growth-vs-profitability tradeoff: a company growing at 60% with a −20% margin scores 40, equal to a company growing at 20% with a +20% margin. The board reads it to sanity-check whether growth is being bought at unhealthy burn or whether margin discipline is constraining growth too far. Common pitfall: which profitability proxy is used materially changes the score (FCF margin is the strictest, EBITDA more flattering, "operating margin" inconsistently defined), so pick one and disclose it next to the number. — Operations KPI anchored to SaaS Metrics Standards Board.
Rogue ID: operations.rule_of_40
Type: Percentage (%)
Domain: Operations
Definition
Composite SaaS health score that sums the company's revenue growth rate and a profitability proxy (commonly EBITDA margin or free-cash-flow margin) into a single percentage. Originally articulated by Brad Feld in 2015 and codified by the SaaS Metrics Standards Board, the rule frames the growth-vs-profitability tradeoff: a company growing at 60% with a −20% margin scores 40, equal to a company growing at 20% with a +20% margin. The board reads it to sanity-check whether growth is being bought at unhealthy burn or whether margin discipline is constraining growth too far. Common pitfall: which profitability proxy is used materially changes the score (FCF margin is the strictest, EBITDA more flattering, "operating margin" inconsistently defined), so pick one and disclose it next to the number.
Formula
Rule of 40 = revenue_growth_rate (%) + profitability_margin (%). Per SMSB, `revenue_growth_rate` is typically YoY ARR or revenue growth; `profitability_margin` is typically EBITDA margin or FCF margin (disclose which). Both inputs are percentages — the output is also a percentage and can be negative when negative margin overwhelms growth.Why it matters
Single-number readout of the growth-vs-burn tradeoff. Lets the board compare a high-growth / high-burn company to a slow-growth / profitable one on one axis, and surfaces unhealthy growth (high growth paid for with margin much worse than negative growth-rate offset).
How to interpret
Per the rule as originally framed by Brad Feld (2015) and the SaaS Metrics Standards Board, a score at or above 40% is the canonical "healthy" threshold for growth-stage SaaS; below 40% signals either growth or margin is under-delivering. Finer stratifications often cited (>50% strong, >60% best-in-class) are industry folk-wisdom, not citation-grade. Always disclose which profitability proxy is used — comparing an EBITDA-margin Rule of 40 to an FCF-margin Rule of 40 is apples-to-oranges and a frequent board-deck error.
Related KPIs
sales.growth_rate_yoysales.gross_marginfinance.net_burn_ratefinance.runway_months
Source
SaaS Metrics Standards Board · section: Rule of 40 — published 2023-01-01.
Why does this cite SaaS Metrics Standards Board? Read the ontology methodology for the published vs editorial tier system, attribution rules, and dispute process.
Metric definitions reference standards published by the SaaS Metrics Standards Board (saasmetricsboard.com). imboard is not affiliated with, endorsed by, or a member of SMSB.
Industry benchmark
A reference distribution sourced from KBCM/Sapphire SaaS Survey 2024 (15th Annual) (2024):
| Percentile | Value |
|---|---|
| 25th | -4% |
| Median | 15% |
| 75th | 31% |
Higher is better.
Stage relevance
| Company stage | Priority |
|---|---|
| Series A | Core |
| Series B | Core |
| Series C+ | Core |
| Public | Core |
Suggested for stages: Series A, Series B, Series C+, Public.
Default owning functions
- Finance
Machine-readable
- This KPI as JSON:
/api/ontology/operations/rule_of_40.json - All Operations KPIs:
/api/ontology/operations.json - Full catalog:
/api/ontology/index.json