What Is the Rule of 40? Balancing SaaS Growth and Profitability

A SaaS company growing 80% a year while losing money and a SaaS company growing 15% a year at a healthy profit can both be "doing well" - but by very different definitions. The Rule of 40 is the heuristic investors use to compare them on the same scale: growth and profitability traded off against each other, added into a single score.

This post explains what the Rule of 40 is, how to calculate it correctly, where it's useful, and where it falls apart.

What Is the Rule of 40?

The Rule of 40 states that a healthy SaaS company's revenue growth rate plus its profit margin should add up to 40% or more.

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

Example: a company growing ARR at 30% year-over-year with a 12% free cash flow margin scores 42 - above the benchmark, even though neither number alone looks exceptional.

🧒 Explained simply Imagine two lemonade stands. One grows fast by giving away free refills and barely breaking even. The other grows slowly but keeps a fat profit on every cup. The Rule of 40 just adds "how fast you're growing" plus "how much profit you're keeping" into one score, so you can compare a fast-but-spendy stand to a slow-but-profitable one on the same scale.

How to Calculate It Correctly

The formula looks simple, but the two inputs need to be defined consistently or the score becomes meaningless.

Growth rate is almost always measured as year-over-year ARR or revenue growth. Quarter-over-quarter growth annualized can work for very early-stage companies, but it's noisier and not directly comparable to the standard benchmark.

Profit margin is the part that varies most between sources. Common choices, in order of how strict they are:

EBITDA margin - the most commonly cited version, especially for public SaaS comparisons.
Free cash flow (FCF) margin - stricter, since it accounts for capital expenditure and working capital changes.
Operating margin - similar to EBITDA but includes depreciation and amortization.

Pick one, state it, and use it consistently period over period. Mixing EBITDA margin one quarter and FCF margin the next will make your trend line lie to you.

Three Ways to Hit 40

The score doesn't care how you get there - which is the point. All three of these companies hit a Rule of 40 score of exactly 40:

Company profile	Growth Rate	Profit Margin	Rule of 40 Score
Hypergrowth, unprofitable	55%	-15%	40
Balanced	30%	10%	40
Profitable, slower growth	10%	30%	40

None of these is objectively "better" by the Rule of 40 alone - the score is intentionally indifferent to the mix. What matters more in practice is whether the mix matches your stage and your investors' expectations. A Series B company posting the "profitable, slower growth" profile may face harder fundraising questions than one showing strong growth, even at an identical score.

Why the Rule of 40 Matters

It's a shared language with investors. Saying "we're at a 52 on the Rule of 40" gives an investor immediate context on how you're trading off growth and burn, without needing your full P&L.

It discourages growth at any cost. Without some profitability counterweight, "growth at all costs" strategies can mask deteriorating unit economics. The Rule of 40 forces growth to be considered alongside how much it costs to produce.

It's used in valuation conversations. Public and late-stage private SaaS companies are frequently benchmarked against the Rule of 40 when comparing valuation multiples - companies clearing 40 by a wide margin often command premium multiples relative to revenue.

Where the Rule of 40 Breaks Down

It's not meaningful pre-$1M ARR. A company at $200K ARR growing 150% with a -200% margin produces a score that looks alarming but is completely normal - early-stage companies are supposed to spend more than they earn while finding product-market fit. The Rule of 40 becomes useful once growth and margin numbers are large enough to be stable.

It ignores capital efficiency and runway. Two companies can both score 40, but one might have 36 months of runway and the other 6. The Rule of 40 says nothing about how sustainable the underlying burn actually is.

It can be gamed by low-quality growth. Revenue growth driven by heavy discounting, one-time deals, or unsustainable promotions can inflate the growth half of the score without reflecting durable demand. Pair the Rule of 40 with retention metrics like Net Revenue Retention to sanity-check whether growth is sticky.

It treats all margin the same. A dollar of margin from genuine operating efficiency is not the same as a dollar of margin from cutting R&D investment that will hurt growth two years from now.

Rule of 40 Benchmarks by Stage

ARR Stage	Typical Growth Rate Range	Typical Margin Range	Rule of 40 Relevance
Under $1M	100-300%+	Often -100% or worse	Not meaningful yet
$1M-$10M	60-150%	-40% to 0%	Directional only
$10M-$50M	40-100%	-20% to 15%	Starts to matter
$50M+	20-60%	0% to 30%+	Closely watched by investors

How to Improve Your Rule of 40 Score

The two levers are growth and margin, and most companies should focus on whichever one is structurally weaker rather than trying to push both simultaneously.

To improve the growth side: reduce churn (it directly increases net new MRR without new acquisition spend), build expansion revenue from existing accounts, and improve trial-to-paid conversion.

To improve the margin side: improve gross margin through infrastructure and support efficiency, reduce CAC relative to LTV, and rationalize spend that isn't driving measurable growth or retention.

In practice, the highest-leverage move for most mid-stage SaaS companies is reducing churn - it improves the growth half of the equation while requiring no additional spend, which simultaneously helps the margin half too.

How to Track Your Rule of 40 Score in Chartsy

Chartsy calculates ARR growth rate from your Stripe or Paddle data so you can pair it with your own margin figures to track your Rule of 40 score over time. You can ask:

"What is my ARR growth rate for the last 12 months?"
"Show net new ARR by quarter"
"What's my net revenue retention this year?"

Connect Stripe and track the growth half of your Rule of 40 →

Frequently Asked Questions About the Rule of 40

What is the Rule of 40 in SaaS? The Rule of 40 states that a healthy SaaS company's revenue growth rate plus profit margin should equal at least 40%. A company growing 30% annually with a 10% profit margin scores 40. It's a heuristic for balancing growth and profitability, not a strict rule.

What margin should I use in the Rule of 40 calculation? EBITDA margin is the most common choice, especially when comparing to public SaaS benchmarks. Free cash flow margin is stricter and accounts for capital spending. Whichever you choose, use it consistently across periods so your trend is comparable over time.

Is the Rule of 40 useful for early-stage startups? Not really below roughly $1M ARR. Early-stage companies are expected to spend more than they earn while finding product-market fit, which produces Rule of 40 scores that look alarming but are completely normal. It becomes a more meaningful benchmark once growth and margin figures stabilize.

Can a company score above 40 and still be in trouble? Yes. A high score driven by unsustainable growth tactics (heavy discounting, one-time deals) or margin gains from cutting investment in the product can mask real problems. The Rule of 40 should be read alongside retention metrics like NRR, not in isolation.

What's a good Rule of 40 score for an investor pitch? Scores meaningfully above 40 - 50 or higher - are generally viewed favorably, especially when paired with strong net revenue retention. But investors typically care more about the trend and the composition of the score (is it driven by durable growth or financial engineering) than the single number itself.