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Growth companies are at the heart of modern capital markets - but they are difficult to value. Traditional ratios such as P/E or price-to-book value reach their limits when companies make losses in order to conquer markets. This is precisely where the Rule of 40 comes in: a simple but surprisingly meaningful indicator that puts growth and profitability in relation to each other - and thus shows whether a business model is economically viable.
The rule itself is simple:
Sales growth (%) + operating margin (%) ≥ 40.
If a company reaches or exceeds this threshold, it is considered efficient and balanced - it is growing strongly without burning excessive capital. If the value is significantly lower, there is a risk of an imbalance between expansion and profitability.
The ratio originally comes from the US software industry, particularly from SaaS companies, which often do not yet report profits but are growing strongly. Investors there were looking for a way to combine growth and efficiency on a single scale. The Rule of 40 provides exactly that - a simple efficiency indicator.
An example illustrates the principle:
- Company A grows by 50% but has an operating margin of -20% → score 30.
- Company B grows by 25 %, achieves +20 % margin → score 45.
Although company A is growing faster, company B is clearly more efficient - and usually more stable in the long term. The decisive factor is the ratio, not the level of growth alone.
The following applies in practice:
- > 50 %: exceptionally strong, growth and profitability in balance.
- 40-50%: solid, sustainable and controlled.
- 30-40 %: acceptable, but often cyclical or low-margin.
- 20-30%: fragile, efficiency problems visible.
- < 20 %: critical, model mostly unbalanced.
For typical SaaS companies, a value above 40% is a sign of a mature, efficient business model.
Examples from practice:
- $SNOW (+0,6 %) (Snowflake): Sales growth ~34%, operating margin ~12% → Score 46.
- $CRM (+1,58 %) (Salesforce): Growth ~11%, margin ~30% → Score 41.
- $PLTR (+3,55 %) (Palantir): Growth ~45%, operating margin ~12% → Score 57.
- $APPN (+0,8 %) (Appian): Growth ~15%, margin -20% → Score -5.
- $V (-0,52 %) (Visa): Growth ~10 %, operating margin ~67 % → Score 77 - exceptionally efficient, hardly cyclical.
However, the metric does not work everywhere. It is tailored to scalable, digital models in which high fixed costs are quickly covered by rising sales. It is less meaningful in capital-intensive or cyclical industries.
Examples where it only works to a limited extent:
- Industry & hardware: Fluctuating margins due to economic cycles, e.g. at $VRT (-1,44 %) (Vertiv) or $ASML (-0,86 %)
Utilities & Energy: Focus is on stability, not growth - a value above 40% would be rather suspicious here.- Biotech & early-stage tech: Low sales and high development costs make the key figure hardly usable.
- Consumer & platform models: High marketing expenditure can distort the score in the short term, which is why a smoothed multi-year value is more meaningful.
The Rule of 40 therefore does not measure valuation, but efficiency. It helps to compare growth companies and assess whether expansion is sensible or expensive.
Some analysts now use extended variants:
- Free cash flow margin instead of operating margin → stronger focus on liquidity.
- Rule of 50 as a premium filter for particularly efficient growth companies.
- Trend analysis over several years → rising scores indicate operational maturity.
In my Hidden Quality Radar (HQR) model, the key figure is included in the Growth & Profitability dimension:
- Scores above 40 receive high scores.
- Scores between 30 and 40 are considered neutral.
- Values below 30 are critically scrutinized.
The key figure also serves as a stability filter in the 10B model (tenbagger approach). A company with high sales growth but a Rule of 40 score below 20 is rarely a sustainable tenbagger - usually just a speculative bet.
The bottom line is that the Rule of 40 is not a dogma, but a helpful compass. It forces discipline - both on the part of management, who strive for profitable growth, and on the part of investors, who want to separate substance from hope. Especially in times of rising interest rates and capital discipline, it is becoming more important again.
Questions for the community:
Which of your portfolio stocks currently fulfill the Rule of 40 - and how stable do they remain over several quarters?
Do you also find the ratio useful outside the SaaS sector - for example in industrial or infrastructure stocks?
Do you actively use the Rule of 40 in your analysis, or is it more of a theoretical guideline for you?
