Rule of 40 Calculator

Last updated: August 4, 2026  ·  Reviewed by the DoCalc team

What Is the Rule of 40?

The Rule of 40 is a rule-of-thumb benchmark stating that a healthy SaaS company's revenue growth rate plus its profit margin should add up to 40% or more. It became popular because it captures a real tradeoff: a company can be unprofitable if it's growing fast enough, or grow slowly if it's highly profitable, but a company that's both growing slowly and burning cash is in trouble on both fronts at once. Unlike the other calculators on this site, the Rule of 40 isn't measuring one dimension of the business — it's a single combined score meant to answer the board-level question "is this company's overall growth-versus-profitability tradeoff healthy," in one number.

The Formula

A company growing 60% annually with a -20% margin scores 40 and passes. A company growing 15% with a 25% margin also scores 40 and passes. Both represent fundamentally different — but equally defensible — strategies: the first is prioritizing growth and accepting a burn, the second is prioritizing profitability and accepting slower growth. The Rule of 40 doesn't prescribe which strategy to pick; it just says the combination needs to add up.

How the Rule of 40 Works

Which Margin Should You Use?

Two versions are common in practice: EBITDA margin (earnings before interest, taxes, depreciation, and amortization) and free cash flow margin. EBITDA margin is more widely used in public-company and later-stage benchmarking since it's easier to calculate from standard financial statements. Free cash flow margin is often preferred by growth-stage investors because it captures capital expenditure and working-capital effects that EBITDA ignores — meaning it's a stricter, more cash-realistic number. Whichever you choose, staying consistent matters more than which one you pick, since you'll be comparing your own score over time.

The score works as a slider, not a fixed split: every point of margin sacrificed needs to be earned back in growth, and vice versa. That's what makes it useful as a single combined signal — a company can consciously trade profitability for growth (or the reverse) and still know whether the trade is landing in healthy territory or not, just by watching whether the two numbers keep summing to 40 or more.

Worked Example: Step-by-Step Calculation

Take a company growing revenue 35% year-over-year with a -5% EBITDA margin (still burning cash, but not heavily).

A score of 30 sits in the "close" range — not failing, but investors would want to see a credible plan to close the 10-point gap, either by accelerating growth or narrowing the margin. Now suppose the same company spends the next year improving efficiency, holding growth steady at 35% but cutting the margin loss to breakeven (0%):

Still short of 40, but the trend matters as much as the absolute number here — a company visibly closing the gap year over year tells a very different story to a board than one stuck at 30 with no improvement plan.

Use Cases: Rule of 40 Benchmarks

Score	Read
Below 30	Below threshold — investors will want a plan to close the gap
30–40	Close — a modest improvement in growth or margin gets you over the line
40+	Passing — the widely cited threshold for a healthy SaaS business
60+	Exceptional — top-quartile performance among public SaaS companies

Boards and investors reach for the Rule of 40 most often during fundraising and annual planning conversations, precisely because it compresses two numbers that are easy to spin in isolation (growth "looks" impressive, or margin "looks" disciplined) into one figure that's much harder to cherry-pick around. Operators use it as a planning constraint: if growth is expected to slow next year, the score forces an explicit conversation about how much of that slack needs to be recovered through margin improvement.

Common Mistakes to Avoid

The most common mistake is switching between EBITDA margin and free cash flow margin from period to period, which makes the trend look noisier or smoother than it actually is — pick one definition and stay consistent. A second mistake is treating the Rule of 40 as a strict pass/fail gate for a very early-stage company, when in reality most pre-product-market-fit companies score well below 40 and that's expected, not alarming. A third mistake is optimizing the score itself rather than the underlying business — cutting growth-driving spend purely to nudge the number over 40 can trade long-term value for a short-term metric win.

Pros and Cons of the Rule of 40

Pros: compresses two competing priorities — growth and profitability — into one comparable number; widely recognized by investors, so it's an efficient shorthand in a pitch or board deck; flexible enough to let a company choose its own growth/margin mix as long as the sum holds.

Cons: the same score can hide very different levels of risk — 60% growth and -20% margin is a much riskier bet than 20% growth and 20% margin, even at the same total; not meaningful for pre-revenue companies; margin definition (EBITDA vs. free cash flow) needs to stay consistent or the trend becomes misleading.

Who Should — and Shouldn't

Use it if you have a revenue base to measure growth against and want one number that captures the growth-versus-profitability tradeoff for board reporting or benchmarking against peers.

Skip it if you're pre-revenue or too early to have a meaningful growth rate — focus on burn rate and runway instead until there's real revenue to measure.

Expert Recommendation

Watch the trend, not just the score. A company moving from 25 to 35 over four quarters is telling a very different story than one flat at 35 the whole time, even though the snapshot score can look similar in any given quarter — the trajectory is often more informative to a board than the number itself.

Conclusion

The Rule of 40 is a deliberately blunt instrument — one number standing in for a real tradeoff between growth and profitability. Used as a quick health check and a talking point for how that tradeoff is being managed, it earns its place; used as a precise target to hit at all costs, it can push a business toward decisions that look good on this one metric and bad everywhere else.

Frequently Asked Questions

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