What Is the Rule of 40? SaaS Health Metric Explained
The Rule of 40 is a simple but powerful SaaS health metric coined by Brad Feld. It states that a healthy SaaS company's revenue growth rate plus profit margin should equal or exceed 40%. The rule balances the tradeoff between growth and profitability — you can grow fast and lose money, or grow slowly and be profitable, as long as the sum passes 40.
Quick Answer
Rule of 40 = Revenue Growth Rate (%) + Profit Margin (%)
Score 40+ = healthy. Above 50 = excellent. Below 25 = needs improvement.
Why the Rule of 40 Matters
Investors use the Rule of 40 as a quick sanity check for SaaS companies. It captures the fundamental tradeoff in SaaS: growing fast requires burning cash (negative margins), while being profitable usually means growing slower. The rule says either path is fine — as long as the combination is strong.
A company scoring 55 (40% growth + 15% margin) is demonstrably healthier than one scoring 30 (50% growth + -20% margin), even though the second company is growing faster. The Rule of 40 rewards balanced, sustainable businesses over pure growth-at-all-costs.
How to Calculate the Rule of 40
Rule of 40 Formula
Rule of 40 = YoY Revenue Growth Rate (%) + Profit Margin (%)
Example: Your YoY revenue growth is 30% and your EBITDA margin is 12%. Rule of 40 score = 30 + 12 = 42 — healthy.
Example: Your YoY revenue growth is 55% and your EBITDA margin is -18%. Rule of 40 score = 55 + (-18) = 37 — slightly below 40, needs improvement.
Real-World Rule of 40 Examples
| Company | Growth Rate | Profit Margin | Rule of 40 |
|---|---|---|---|
| Atlassian | ~20% | ~10% | ~30 |
| Datadog | ~25% | ~2% | ~27 |
| Snowflake | ~35% | ~-3% | ~32 |
| Zoom | ~10% | ~8% | ~18 |
Note how companies with high growth but low margins (Snowflake) can still pass the Rule of 40, while companies with moderate growth and moderate margins (Zoom post-pandemic) may fall below. The rule reveals whether growth is being bought efficiently.
Rule of 40 Benchmarks
| Score | Verdict | What It Means |
|---|---|---|
| 50+ | Excellent | Strong growth with healthy or acceptable margins |
| 40-50 | Healthy | Balanced growth and profitability |
| 25-40 | Caution | Either growth is slowing or losses are too high |
| Below 25 | At Risk | Insufficient growth or profitability; fundamental issues |
How to Improve Your Rule of 40 Score
You can improve from either side: increase growth or improve margins. The approach depends on your stage:
Increase Growth Rate
- Accelerate new customer acquisition in efficient channels
- Drive expansion revenue from existing customers
- Enter new market segments or geographies
- Launch new products or features that expand TAM
Improve Profit Margin
- Reduce CAC by shifting to organic and referral channels
- Improve gross margin by optimizing infrastructure costs
- Reduce churn to increase LTV and lower acquisition burden
- Optimize sales efficiency and reduce overhead per revenue dollar
Common Rule of 40 Mistakes
Common Mistake
Using revenue growth instead of ARR growth. The Rule of 40 should use recurring revenue growth (ARR or MRR), not total revenue. Total revenue includes one-time fees and services, which distorts the growth rate and makes the score look healthier than it is.
Calculate Your Rule of 40 Score
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