The Rule of 40: What It Measures and How to Apply It

The Rule of 40 is a quick test for software and other recurring-revenue businesses: add your revenue growth rate to your profit margin, and if the sum is 40 percent or more, growth and profitability are in a healthy balance. It was created to keep two goals in view at once. A company can grow fast by spending heavily, or stay profitable by growing slowly, and the rule asks whether the combination is good enough. This guide defines the rule precisely, works through three company profiles with checked arithmetic, explains how to choose the margin measure and the growth measure, shows how to use the rule to evaluate trade-offs, lists its limits and describes how to present it to a board. It belongs to unit economics and budgeting and forecasting, builds on net revenue retention and gross revenue retention, and leads to the SaaS magic number and burn multiple.

The definition

Rule of 40 score = Revenue growth rate (%) + Profit margin (%)

A score of 40 or more passes the test. The growth rate is normally year-over-year revenue growth, and the profit margin is a margin measure chosen and held constant, most often free cash flow margin or EBITDA margin. Because the choice of margin changes the answer, the report must state which one was used. The rule is a rule of thumb. It was not derived from a law of economics, and it should be read as a conversation starter and not a verdict.

Three company profiles

All numbers are hypothetical.

Check: 60 - 25 = 35; 20 + 25 = 45; 30 + 12 = 42. Company A is growing fast and burning cash, and its score of 35 says that the growth is not yet earning enough to justify the burn, though that may change as it scales. Company B is highly profitable and growing slowly, and the rule says this is a healthy business in a different shape. Company C balances the two. The rule treats a point of growth and a point of margin as equal, which is a simplification: a point of growth at a small company is easier to get than at a large one, and a point of margin is worth different amounts at different stages.

A calculation from financial statements

A company had revenue of $10.0 million last year and $13.5 million this year. Its EBITDA this year was a loss of $0.9 million.

• Revenue growth = (13.5 - 10.0) / 10.0 = 35.0 percent
• EBITDA margin = -0.9 / 13.5 = -6.7 percent
• Score = 35.0 - 6.7 = 28.3

The company is 11.7 points short. Consider two paths to close the gap, using illustrative assumptions.

The first three paths all fall short, and each moves the score only a little because the trade between growth and margin is close to one-for-one. The fourth path, which improves unit economics rather than trading one for the other, is the one that makes real progress. This is the practical lesson of the rule: it is hardest to pass by trading growth for margin, and easiest by improving the economics underneath, such as gross margin, retention, sales efficiency and pricing. See SaaS gross margin and how to raise prices.

Choosing the margin measure

Choose one and apply it consistently, and show a second when the difference is large. A company that collects annual contracts upfront can look strong on free cash flow in a growth year and weak the year it slows. Stock-based compensation is a real cost that EBITDA excludes, so if it is large, note it.

Choosing the growth measure

Most use year-over-year revenue growth for the last twelve months. For fast-changing businesses, some use the annualized growth of the latest quarter, which responds more quickly but can be noisy. ARR growth is another option for subscription businesses and can run ahead of recognized revenue. Whichever you use, apply the same measure to both the numerator and the targets. For acquired growth, show organic growth separately.

When the rule helps

• As a single number in board discussions, it focuses attention on the trade-off.
• For comparison with peers, with the margin measure matched.
• For planning, to test whether a plan that raises burn is also expected to raise growth by a sufficient amount.
• For investment decisions, as one of several screens.

When the rule misleads

• Early-stage companies. A company with $2 million in revenue and 150 percent growth is not well described by a combined score. Efficiency measures such as the burn multiple work better. See burn multiple.
• Large and mature companies. Growth of 10 percent is respectable at scale, and the rule can penalize them.
• Different business models. A product business with inventory and heavy working capital differs from software. If you apply the rule outside software, adjust expectations and use free cash flow carefully.
• Quality of growth. Growth bought with deep discounts or with customers who churn quickly counts the same as durable growth. Check retention.
• Quality of profit. Margin improved by deferring necessary investment is not sustainable.
• One-time items. Large one-off gains and charges distort the margin.

Using the rule in a plan

When building a budget, calculate the expected score for each scenario. If the plan scores 25 and the board expects 40, show the levers that would close the gap, with numbers: price, gross margin, retention, sales efficiency and operating expense growth. A table that compares scenarios by score, cash need and risk is more useful than a single target. Link the scenarios to the cash forecast so that the plan does not rely on funding that may not be available. See budgeting and forecasting.

Presenting it to a board

Show three years of history and the plan, with the growth and margin components plotted separately and the combined score. Define the margin measure on the slide. Add the retention figures and the gross margin, which explain most of the movement in the score. Close with the two or three actions that would change the score by the largest amounts, with estimated effects. Resist the temptation to adjust the measure to pass the test.

Common mistakes

• Changing the margin measure to reach 40.
• Using different time periods for growth and margin.
• Treating the rule as a target to hit this quarter.
• Ignoring retention and gross margin.
• Applying it unchanged to very small or very large companies.
• Excluding stock compensation without saying so.

Improving the score through unit economics

Return to the company with a score of 28.3 (35.0 percent growth and a margin of -6.7 percent on $13.5 million of revenue and an EBITDA loss of $0.9 million). Compare what several operating improvements would do, one at a time, using stated assumptions.

A 3 percent price increase with no loss of volume. Revenue rises to 13.5 × 1.03 = $13.905 million. The added $0.405 million drops straight to profit, so EBITDA becomes -0.9 + 0.405 = -$0.495 million.

• Growth = (13.905 - 10.0) / 10.0 = 39.05 percent
• Margin = -0.495 / 13.905 = -3.56 percent
• Score = 39.05 - 3.56 = 35.5, an improvement of about 7.2 points

The assumption of no lost volume has to be tested, as shown in how to run a price test. If volume fell by 2 percent, the gain would be smaller, but the example shows why price is such a powerful lever for the score: it raises both terms at once.

A 5-point improvement in gross margin. On revenue of $13.5 million, five points of margin is 0.05 × 13.5 = $0.675 million. EBITDA becomes -0.9 + 0.675 = -$0.225 million, a margin of -1.7 percent, and the score rises from 28.3 to 33.3 (35.0 - 1.7), an improvement of 5 points. See SaaS gross margin.

A 3-point improvement in gross revenue retention. If the recurring base is about $12 million, three points of retention is $0.36 million of revenue kept each year. Over the year it supports growth and, since it costs less than winning new customers, it flows to margin. See gross revenue retention.

Cutting sales and marketing spend by $1.0 million. EBITDA becomes +$0.1 million, a margin of +0.7 percent. If growth then falls from 35 to 28 percent because there are fewer new customers, the score is 28.7, no better than before. Cuts that reduce growth by nearly as much as they raise margin do not move the score.

The pattern is useful in board discussions. Actions that improve efficiency, such as price, gross margin and retention, raise the score. Actions that trade growth for margin barely change it.

Using the rule outside software

The rule is built on the economics of subscription software, where gross margins are high, incremental costs of growth are modest and recurring revenue is predictable. A consumer-product company with inventory has lower gross margins, heavier working capital and lumpier demand. If you want a growth-plus-margin check for such a business, adapt it with care. Use the same method each year, choose free cash flow or operating margin, expect lower targets than software and always read it with inventory turns and cash conversion. Several companies in product categories use the combination of growth and margin as an internal discipline without a fixed target of 40. The aim is to prevent growth that destroys cash.

Tracking it quarterly

Calculate the score each quarter from the trailing twelve months, and plot growth and margin as separate lines with the sum. Look at the direction. A score rising from 25 to 32 over four quarters, driven by margin, tells a different story from one that falls from 45 to 38 as growth slows. Add a note on any one-time items that distort either part. When presenting to a board, include the score for the plan and for a downside case, so that decisions about hiring and spending are made with the effect on the score in view.

FAQs

What is the Rule of 40?

A guideline that says the sum of a company's revenue growth rate and profit margin should be at least 40 percent.

Which profit margin should I use?

Free cash flow margin or EBITDA margin are the most common. Choose one, state it and use it consistently.

Does the rule apply to non-software businesses?

It was designed for software and recurring-revenue companies. For businesses with inventory and heavier capital needs, use it with care and adjust expectations.

What is a score below 40 telling me?

That growth and profitability together are below the common benchmark. Look at the drivers, such as gross margin, retention and sales efficiency, before changing the strategy.

Is a higher growth rate always worth a lower margin?

Not automatically. The rule treats them as one-for-one, and the right trade depends on the quality of growth, the cost of capital and the stage of the company.