What Is the Rule of 40?
Every SaaS board deck eventually gets asked the same blunt question: is this growth worth what it costs? The Rule of 40 turns that question into one number — add a company's year-over-year revenue growth rate to its profit margin, and the total should be 40% or higher. Score below 40 and the business is spending too much to grow too little; score well above it and growth and profitability are both pulling their weight.
Investors reach for it because it's fast. A single glance at growth rate and margin — no cap table, no cohort curves, no 40-slide board deck — tells you whether a company is buying revenue it can't afford or leaving profitable growth on the table by playing it too safe. It doesn't replace deeper diligence, but as a first filter across a portfolio of SaaS companies, nothing is quicker.
The Rule of 40 Formula, Step by Step
The formula has two inputs and one addition: Rule of 40 Score = Revenue Growth Rate (%) + Profit Margin (%). Growth rate is straightforward — year-over-year, or annualized quarter-over-quarter, revenue growth. Profit margin is where founders disagree: most investors use free cash flow margin (FCF ÷ revenue) or EBITDA margin; either works, as long as you stay consistent quarter to quarter so the trend line stays honest.
A worked example: a startup grew revenue from $4M to $6M this year — 50% growth — while running an EBITDA margin of -15% because it's still spending to fund that growth. 50 + (-15) = 35, just under the bar. Splitting the score into growth and margin shows exactly where the gap is: trim the loss, or find another 5-10 points of growth.
What Counts as a Good Rule of 40 Score?
There's no regulator-issued cutoff, but the reference points converge on a similar scale. Public SaaS companies above 40% are generally considered healthy; the top decile clears 60% or more in strong years. Early-stage companies still finding product-market fit often run below 40 — the number becomes a meaningful gate once there's real recurring revenue to grow and protect, not before.
Stage matters more than the raw number suggests. A seed-stage company posting a 25 is not necessarily in trouble if the shortfall is pure growth investment with a clear path to expansion revenue; a Series C company posting the same 25 is a different conversation, because the market expects discipline to have replaced the land-grab by then. Read the score next to the stage, not against a single universal bar.
≥40%
the widely cited minimum for a "healthy" SaaS growth/profit balance
60%+
typical score of top-decile public SaaS companies in strong years
<0%
growth minus losses net negative — a warning sign regardless of growth rate
Two Different Paths to the Same Score
A 40 is a 40 whether it comes from 60% growth and -20% margin, or 15% growth and 25% margin — but the two profiles carry very different risk. The growth-heavy path is common at seed and Series A, where founders deliberately trade margin for market share. The profit-heavy path shows up more at Series C and later, when capital is scarcer and investors reward discipline over land-grabs.
| Growth-heavy path | Profit-heavy path | |
|---|---|---|
| Typical mix | 60% growth, -20% margin = 40 | 15% growth, 25% margin = 40 |
| Common stage | Seed – Series A | Series C and later |
| Main risk | Burn outruns the next round | Growth stalls, multiple compresses |
| What investors watch next | Burn multiple, runway | Net revenue retention, expansion |
Rule of 40 vs. Burn Multiple: Different Questions
The Rule of 40 and burn multiple get confused because both grade the growth-vs-spending trade-off, but they answer different questions. The Rule of 40 asks whether the whole company's growth-and-profitability balance clears a bar — a board-level health check, usually read quarterly or annually. Burn multiple asks how much cash bought the most recent dollar of new recurring revenue — a sharper, month-to-month discipline metric for the marginal spend.
Use them together, not instead of each other: a company can clear 40 on the strength of last year's growth while its current burn multiple is deteriorating — the Rule of 40 lags, burn multiple leads. If you haven't benchmarked yours yet, the burn multiple formula and benchmark scale are covered in a companion breakdown on this blog.
Common Mistakes When Calculating It
Four mistakes distort the score most often. Using bookings growth instead of recognized revenue growth inflates the number with deals that haven't actually landed. Switching between margin definitions — FCF margin one quarter, GAAP net margin the next — breaks the trend line the metric is supposed to show. Applying it to companies below roughly $1-2M in ARR, where a single deal swings growth rate by double digits, produces noise dressed up as signal. And judging every stage against the same 40% bar ignores that a seed-stage company trading margin for growth is doing exactly what it should.
The fix for all four is the same habit: recompute the score every quarter using the same margin definition, plot it as a line rather than a point, and read the trend against your own stage instead of a single universal target. A rising line from 25 to 35 over three quarters is a healthier signal than a static 42 that hasn't moved.
Feel the Trade-off, Not Just the Formula
Reading the formula isn't the same as feeling the trade-off it measures. In Founder Runway, every hire, marketing push, or pricing change moves MRR growth and Cash in the same turn — spend more and growth usually follows, but so does burn, and a run that looks fine on paper can quietly slide under 40 for several turns before the Cash trend makes it undeniable.
The Bottom Line
Rule of 40 Score = Revenue Growth Rate + Profit Margin. Above 40 is the widely cited healthy range, below 40 means growth and profitability together aren't pulling their weight, and the trend across quarters matters more than any single reading. Track it alongside burn multiple and runway — one grades the balance, the other grades the spend, and runway tells you how long you have to fix either one.
Frequently asked questions
What is the Rule of 40?
The Rule of 40 is a SaaS benchmark stating that a company's revenue growth rate (%) plus its profit margin (%) should add up to 40% or more. It's used as a fast, single-number check on whether growth and profitability together are healthy, without needing a full financial model.
How do you calculate the Rule of 40?
Add your year-over-year revenue growth rate to your profit margin — most often free cash flow margin or EBITDA margin, kept consistent across quarters. A company growing 50% with a -15% EBITDA margin scores 35, just under the 40% bar.
What is a good Rule of 40 score?
40% or higher is the widely cited minimum for a healthy SaaS company. Top-decile public SaaS companies clear 60%+ in strong years, while early-stage companies still finding product-market fit often run below 40 without it being a red flag on its own.
Does the Rule of 40 apply to pre-revenue or early-stage startups?
It's most meaningful once a company has real recurring revenue to grow and protect. Pre-revenue or sub-$1-2M ARR companies see the score swing wildly from a single deal, which produces noise rather than signal — runway and product-market fit matter more at that stage.
What's the difference between the Rule of 40 and burn multiple?
The Rule of 40 grades a company's overall growth-and-profitability balance, typically read quarterly or annually. Burn multiple grades how much cash it took to add the most recent dollar of net new recurring revenue — a sharper, faster-moving efficiency metric. They're complementary, not substitutes.
Test this decision in the game.
Apply the same assumption across one run; which metric burned three turns later?