Growth or profitability? For most SaaS founders, the answer used to be growth at all costs. That changed when capital got expensive and investors started asking a different question: are you growing efficiently?
The Rule of 40 is the shorthand that answers it. It collapses two metrics, growth rate and profit margin, into one number that lets investors compare companies across stage and category in seconds. This guide walks through how to calculate it, what counts as healthy, and where founders most often misuse it.
The Rule of 40 says a SaaS company’s growth rate plus profit margin should equal or exceed 40 percent. Investors use it to weigh growth against efficiency. Scoring above 40 signals capital efficiency; falling below flags a problem with cost discipline or growth velocity.
What Is the Rule of 40?
The Rule of 40 is a benchmark that says a healthy SaaS company’s annual revenue growth rate plus profit margin should be at least 40 percent. It was popularized by Brad Feld and Fred Wilson in the mid-2010s and has since become a default scorecard for SaaS investors and boards.
The logic is simple: you can be a fast-growing company burning cash, or a slower-growing company that is profitable, and either path can be healthy. What is not healthy is slow growth combined with losses. The Rule of 40 captures that trade-off in a single number that is hard to fake.
For most SaaS companies, the profit margin used in the formula is EBITDA margin or free cash flow margin, not GAAP net income. Both growth and profit are expressed as percentages, and the two are simply added together. The number you get is your Rule of 40 score.
How to Calculate the Rule of 40
To calculate the Rule of 40, add your year-over-year revenue growth rate to your EBITDA margin or free cash flow margin, both as percentages. A score of 40 or higher is considered healthy.
The formula:
Rule of 40 score = Revenue growth rate (%) + EBITDA margin (%)
Example:
ARR last year: $10,000,000
ARR this year: $14,000,000
Growth rate: 40%
EBITDA margin: -10%
Rule of 40 score = 40% + (-10%) = 30% (below threshold)
A company that is breakeven and growing 40 percent year over year hits the rule exactly. So does a company growing 20 percent with a 20 percent EBITDA margin, or a profitable company at 50 percent margin growing slowly. All three look the same to the Rule of 40, which is exactly the point. If your books are not closing cleanly enough to produce a reliable EBITDA figure, our financial operations team handles monthly close and KPI reporting for venture-backed startups.
Why Investors Use the Rule of 40
Investors use the Rule of 40 because it is one of the few metrics that captures both sides of the SaaS equation in one number. Pure growth metrics ignore burn. Pure profitability metrics ignore the value of compounding. The Rule of 40 forces both to live in the same conversation.
For growth-stage SaaS companies, the Rule of 40 is now standard in board decks, investor updates, and Series B and later diligence. Bessemer, Insight, and other large SaaS investors publish public benchmarks against it. Public SaaS comparables are screened on it before any valuation work begins.
Our SaaS finance practice shows how investors layer the Rule of 40 onto other capital efficiency metrics during fundraising conversations. For SaaS finance leaders, knowing your number cold before the meeting is table stakes.
Rule of 40 Benchmarks by Stage
Rule of 40 expectations shift with stage. Earlier companies get more credit for growth; later companies are expected to show profitability moving in the right direction.
Seed and Series A
Most seed and Series A companies score well below 40 because they are burning hard to find product-market fit. Investors do not penalize this; they look at whether the trajectory is improving and whether growth is accelerating. Hitting 40 at this stage is rare and not strictly necessary.
Series B and C
By Series B, investors expect the company to be approaching or hitting the Rule of 40. Growth of 60 to 80 percent year over year with EBITDA losses in the 20 to 40 percent range is common and acceptable. Below 30 starts to raise questions about capital efficiency.
Late stage and pre-IPO
Late stage companies are expected to comfortably exceed 40, often hitting 50 or higher. Best-in-class public SaaS companies frequently land between 50 and 80 on the Rule of 40 score. Anything under 30 at this stage usually leads to multiple compression at valuation.
Limitations and Common Misuses
The Rule of 40 is useful, but it is not a complete picture. The most common misuses come from founders applying it at the wrong stage, mixing GAAP and non-GAAP margins inconsistently, or hiding burn through accounting gymnastics.
First, the rule is designed for SaaS companies with predictable, recurring revenue. It is less useful for usage-based pricing, marketplace businesses, or services revenue mixed in. Apply it cleanly only to subscription revenue.
Second, the choice of profit margin matters. EBITDA, free cash flow, and adjusted EBITDA can produce wildly different scores for the same company. Be transparent about which margin you are using and apply it consistently quarter over quarter.
Third, the rule says nothing about retention, gross margin quality, or customer concentration. A company hitting 40 with 70 percent net retention and a single whale customer is not as healthy as it looks. Investors will check those metrics separately. If you are preparing for diligence, our financial operations team helps you get ready for what investors actually pull beyond the headline score.
Frequently Asked Questions
Is the Rule of 40 only for SaaS companies?
It is most useful for SaaS and other subscription businesses with predictable recurring revenue. It can be applied loosely to other software businesses, but it does not work well for hardware, services-heavy, or transactional businesses where revenue and margin profiles are different.
What profit margin should I use, EBITDA or free cash flow?
Both are used in practice. EBITDA is more common in board decks and investor updates because it is easier to calculate and benchmark. Free cash flow is more conservative and is preferred by late-stage and growth equity investors. Be consistent and clear about which one you report.
What is a good Rule of 40 score?
Forty is the threshold. Best-in-class public SaaS companies often score 50 to 70. Anything above 40 is considered healthy. Below 40 means either growth or efficiency needs work. Below 30 at scale signals a structural issue with the business model.
How is the Rule of 40 different from the burn multiple?
The Rule of 40 balances growth and margin. The burn multiple measures how much cash you burn per dollar of net new ARR. They answer different questions: Rule of 40 is about overall efficiency, burn multiple is about capital efficiency of new growth. Most investors track both.
Can a company score above 40 and still be unhealthy?
Yes. A company with strong topline growth but high customer concentration, weak net retention, or unsustainable gross margins can hit 40 and still be a poor investment. Always read Rule of 40 alongside retention, gross margin, and CAC payback.
How often should I report my Rule of 40 score?
Quarterly is standard for most board reporting. Monthly tracking is useful internally for finance and leadership, but the metric is noisy at the monthly level. Use trailing twelve months for growth and EBITDA to smooth out timing effects.
Why does the Rule of 40 use 40 percent specifically?
The 40 percent threshold emerged from observed performance of best-in-class public SaaS companies in the early 2010s. It was not derived from theory; it was an empirical benchmark that stuck because it produced sensible answers across stage and category.
Build a Reliable Rule of 40 Foundation?
Hitting your Rule of 40 number cleanly requires a tight monthly close, accurate ARR tracking, and consistent margin reporting. Escalon’s outsourced finance team builds these foundations for venture-backed SaaS companies so the number you take to your board is the number investors will get to when they audit it themselves.
If your Rule of 40 score is off by 5 points depending on which spreadsheet you open, let’s fix that.
