Rule of 40

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This calculator provides estimates for informational purposes only and does not constitute financial, medical, legal, or tax advice. Always consult a qualified professional about your specific situation.

Calculating a SaaS Company’s Rule of 40 Score

The Rule of 40 is a widely-cited SaaS and subscription-business heuristic stating that a healthy company’s revenue growth rate plus its profit margin should add up to 40% or more. Enter current and prior period revenue along with a profit figure, and this calculator combines growth rate and profit margin into a single score, checked against that 40% threshold.

This is distinct from the EBITDA & EBITDA Margin Calculator calculator (a standalone profitability figure with no growth component) and the Break-Even Point Calculator calculator (a break-even threshold, not a combined growth-and-profitability score) — the Rule of 40 is its own single combined metric used specifically to gauge SaaS business health.

The Formula

  1. Growth rate = (Current Revenue − Prior Revenue) ÷ Prior Revenue, as a percentage.
  2. Profit margin = Profit ÷ Current Revenue, as a percentage — the profit figure is commonly EBITDA, operating income, or free cash flow.
  3. Rule of 40 score = Growth Rate + Profit Margin. A score of 40% or more clears the commonly-cited healthy threshold.

Worked Example

$1,500,000 current revenue, $1,000,000 prior revenue, and $75,000 profit:

  1. Growth rate: 50.0% (($1,500,000 − $1,000,000) ÷ $1,000,000).
  2. Profit margin: 5.0% ($75,000 ÷ $1,500,000).
  3. Rule of 40 score: 55.0% — clears the 40% threshold, driven mostly by strong growth.

Key Factors to Consider

  • The “right” balance between growth and profitability shifts over a SaaS company’s own lifecycle. An early-stage company is often expected to lean heavily on growth (accepting low or negative margin) to establish market position, while a more mature company is generally expected to shift toward profitability as growth naturally slows — the same Rule of 40 score can represent a very different story depending on the company’s stage.
  • Which profit metric is used (EBITDA, operating income, or free cash flow) meaningfully changes the resulting score. These three profitability measures can differ significantly for the same company, especially one with heavy capital expenditures or working-capital swings — the specific choice should stay consistent when tracking the metric over time or comparing against another company’s own reported figure.
  • Investors and analysts commonly use the Rule of 40 as one input among several, not a standalone verdict on a company’s health. Net revenue retention, customer acquisition cost payback period, and gross margin are all commonly examined alongside the Rule of 40 for a fuller picture of a SaaS business’s actual quality, not this single combined score in isolation.
  • A company’s growth rate can look artificially inflated or deflated by a single unusual period. A large one-time contract, an acquisition, or a temporary slowdown can distort the growth-rate half of the score for that specific measurement period — looking at the trend over several periods, rather than one snapshot, gives a more reliable read.

Common Mistakes

  • Treating 40% as a hard pass/fail line. The threshold is a commonly-cited rule of thumb, not a strict standard every healthy business must clear — a company slightly below 40% with a clear path to improving isn’t automatically unhealthy.
  • Applying it outside SaaS/subscription businesses. The Rule of 40 was popularized for recurring-revenue businesses specifically, where growth and profitability trade off in a particular way. It’s less meaningful for businesses with very different economics.
  • Ignoring which side of the score is doing the work. A 40% score from 40% growth and 0% margin looks very different from one built on 5% growth and 35% margin — the balance between growth and profitability matters for understanding a business’s actual trajectory, not just the combined number.

Useful to Know

  • Need to check the profit half of this score on its own? EBITDA & EBITDA Margin Calculator computes a standalone EBITDA figure.
  • Wondering when a business actually starts turning a profit? Break-Even Point Calculator finds the break-even point separately from this combined growth-and-profitability score.
  • Want to see the underlying cash movement behind the profit figure? Cash Flow Calculator tracks cash in and out over a period.

Source: Wikipedia: Rule of 40%.

Frequently Asked Questions

What is the Rule of 40?

The Rule of 40 is a widely-cited SaaS and subscription-business heuristic: a healthy company's revenue growth rate plus its profit margin should add up to 40% or more. It's meant to balance growth and profitability -- a fast-growing but unprofitable company and a slower-growing but highly profitable one can both be considered healthy under this rule.

How is the Rule of 40 score calculated?

Score = Revenue Growth Rate (%) + Profit Margin (%). Growth rate compares current revenue to a prior period; profit margin divides a profit figure (commonly EBITDA, operating income, or free cash flow) by current revenue.

Does the Rule of 40 apply to every business?

It was popularized for SaaS and subscription businesses specifically, where growth and recurring-revenue profitability are both closely watched. It's less commonly applied to businesses with very different economics (e.g. capital-intensive manufacturing), so treat it as a SaaS-specific heuristic rather than a universal rule.

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