The Rule of 40 treats a point of growth and a point of profit as equal. The Rule of X does not - it weights growth more heavily, because growth compounds and is harder to buy back than margin. Score your growth-weighted balance and see if you clear the bar.
Year-over-year revenue growth.
Free cash flow or operating margin. Can be negative.
How many points of value each point of growth is worth. 2-3 is common.
Your score at different growth weights, holding growth and margin fixed. Higher weights flatter faster growth.
| Growth weight | Weighted growth | Rule of X score | Verdict |
|---|
value of a growth point vs a margin point
same threshold as the Rule of 40
elite growth-stage SaaS
A point of growth compounds into next year's revenue and is expensive to win back once it's lost. A point of margin is a one-time saving you can usually find when you need it. The two are not equal, so adding them one-for-one, the way the Rule of 40 does, under-credits the company that is genuinely growing.
The Rule of X prices that difference in. It multiplies growth by a weight before adding margin, so the score reflects the long-run value of growth rather than treating it as interchangeable with a cost cut.
Rule of X = growth × weight + margin Example: 40% growth, a 10% margin, and a weight of 2:
A 60% grower at a -10% margin scores 50 on the Rule of 40, the same as a flat company at a 50% margin. Once growth is weighted, the fast grower looks far stronger. The unweighted rule can flag healthy growth-stage companies as failing, which is exactly the gap the Rule of X is built to close.
The weight is a lever, so pick one you can defend - 2 to 3 is common - and apply it consistently. The score rewards growth, so a high number built on cheap, churning growth flatters you. Pair the Rule of X with retention and burn, not in isolation.
The Rule of X is a growth-weighted version of the Rule of 40: it takes your year-over-year revenue growth, multiplies it by a weight, then adds your profit margin. It credits growth more heavily than profit because growth compounds into future revenue, where margin is a one-time saving. The result is a single score, like the Rule of 40, but tilted toward growth.
The Rule of 40 adds growth and margin one-for-one, treating a point of each as equal. The Rule of X multiplies growth by a weight (often 2 to 3) before adding margin, so fast growers score higher than the plain rule would credit them. At a weight of 1 the two are identical. See the Rule of 40 for the unweighted version.
A weight of 2 to 3 is the common range. Higher weights suit earlier, growth-stage companies where growth is the main story, and lower weights suit more mature companies where margin should carry more of the score. The weight is a lever, so pick one you can justify and apply it consistently when comparing companies.
It was popularised by Bessemer Venture Partners as a refinement of the Rule of 40 for growth-stage software. Their argument is that a point of growth is worth more than a point of profit, because growth compounds over time and is expensive to win back once lost, so the score should weight it accordingly.
More is generally better, but the score rewards growth, so a high number built on cheap, fast-churning growth can mislead. The premium only makes sense for efficient, retained growth. Pair the score with net revenue retention and burn before reading it as a clean positive.
Clearing 40 is the entry bar, the same floor as the Rule of 40, and it maps to Bessemer's good tier. From there the better and best tiers sit higher, at roughly 50 and 70 or more. Because the weight inflates the growth term, the entry bar is easier to clear for fast growers, which is the point - it surfaces companies the unweighted rule under-credits. See Rule of X.
That is the whole point of the score. Bessemer's data on public cloud companies found that a 1% increase in growth lifts the revenue multiple about 2.3x as much as a 1% increase in FCF margin, which is why growth is weighted. In their analysis the Rule of X explained roughly 62% of the variation in the forward revenue multiple, against about 50% for the plain Rule of 40. In short, it tracks what a company is worth better than the unweighted rule. To turn a score into an actual price, see our guide to SaaS ARR multiples.
Bessemer defines the Rule of X with free cash flow (FCF) margin, the same input the Rule of 40 increasingly uses. FCF is harder to flatter than operating or net margin because it reflects cash actually generated after working capital and capex, so it is the cleaner read on whether growth is being funded by the business or by investors. Use FCF margin if you have it; an operating or EBITDA margin is a workable stand-in for a quick estimate, but be consistent across any companies you compare.
Bessemer frames it in tiers rather than a single bar. A roughly 40 score is good, about 50 is better, and 70 or higher is best-in-class. Those tiers line up with Bessemer's worked examples: around 12% growth doubled plus 16% FCF margin lands at 40 for a good score, about 15% growth doubled plus 20% margin reaches 50 for the better tier, and about 25% growth doubled plus 20% margin hits 70 for the top tier. 40 is the entry bar, the same floor as the Rule of 40, while the better and best tiers sit higher. Separately, in the public-cloud market measured at Bessemer's 2.3x weight, the top decile averages around 80 and the very top a handful score 90 or more, but that is a market distribution rather than the framework's tiers.
The Rule of X leans on your growth rate, so the number is only as good as the revenue behind it. Mowt tracks your MRR, ARR and growth rate straight from Stripe, updated daily.
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