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Rule of 40

Rule of 40 is a SaaS heuristic: growth rate (%) + profit margin (%) should be ~40%+. It balances growth and profitability.

Updated 2026-01-23

Definition

Rule of 40 is a SaaS heuristic: growth rate (%) + profit margin (%) should be ~40%+. It balances growth and profitability.

Formula

Rule of 40 score = revenue growth (%) + profit margin (%)

Example

If revenue growth is 35% and profit margin is 10%, the Rule of 40 score is 45% (often considered strong).

How to use it

  • Use it as a stage-aware heuristic, not a universal law.
  • Be explicit about the margin type (EBITDA vs operating vs FCF) and the growth definition.

Common mistakes

  • Mixing margin types (EBITDA vs FCF) without clarity.
  • Using the score as a target without considering stage and motion.

Measured as

Rule of 40 score = revenue growth (%) + profit margin (%)

Misused when

  • Mixing margin types (EBITDA vs FCF) without clarity.
  • Using the score as a target without considering stage and motion.

Operator takeaway

  • Use it as a stage-aware heuristic, not a universal law.
  • Be explicit about the margin type (EBITDA vs operating vs FCF) and the growth definition.
  • Keep Rule of 40 consistent by cohort, segment, and period before you use it as a decision signal in planning or reporting.
  • Interpret the metric alongside retention, margin, or payback so one ratio does not hide the real operating trade-off.

Next decision

  • Quantify the impact with Rule of 40 Calculator if you need to turn the definition into an operating assumption.
  • Read Rule of 40: definition, formula, and how to interpret it if the decision depends on interpretation, policy, or trade-offs beyond the raw formula.

Where to use this on MetricKit

Calculators

Guides