Revenue Metrics

Rule of 40: Growth Rate + Profit Margin ≥ 40

The combined sum of growth rate and profit margin should be at least 40 for a healthy SaaS business.

Definition

The Rule of 40 states that for a healthy SaaS or subscription business, the sum of the year-on-year revenue growth rate and the operating profit margin (or free cash flow margin) should be at least 40. It is the headline efficiency benchmark used by growth-stage investors and public market analysts.

Formula

Rule of 40 = YoY Revenue Growth Rate (%) + Operating Profit Margin (%)

Rule of 40 = Growth Rate % + Profit Margin %

Worked example

A business growing 60% YoY at a -20% operating margin scores 40 — passes. A business growing 25% YoY at 20% operating margin also scores 45 — passes. A business growing 15% YoY at -30% operating margin scores -15 — fails by a wide margin.

Why it matters

The Rule of 40 captures the trade-off every revenue leader makes between growth and profitability. It rewards profitable slow-growth businesses and unprofitable hyper-growth ones equally, so long as the combination is sufficient. It is the single most cited operating benchmark in growth-stage SaaS.

Common mistakes

Using gross margin instead of operating margin (overstates the score)
Mixing reported and non-GAAP profit measures inconsistently
Treating the Rule of 40 as a target rather than a floor

Related terms

ARR Magic Number Gross Margin

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