What is the Rule of 40?
Short Answer
The Rule of 40 states that a company's growth rate plus profit margin should total 40% or more — companies scoring below 40% risk unsustainable unit economics or insufficient growth.
Full Explanation
The Rule of 40 is a heuristic for growth-stage companies: (Annual Growth Rate %) + (EBITDA Margin %) ≥ 40%. For example, a company growing 30% annually with a 15% EBITDA margin scores 45 — healthy. One growing 50% but with −20% margin also scores 30 — problematic because it is burning capital unsustainably. The rule forces trade-off thinking: you can invest heavily to grow fast (high growth, low margin) or optimise for profitability (lower growth, high margin), but you cannot sacrifice both. Companies above 40 are building sustainable businesses; below 40 suggests either unsustainable burn or insufficient growth momentum. High-growth SaaS companies routinely operate below 40 in early stages because they prioritise growth, accepting losses. However, by Series B/C, expectations shift toward higher scores — investors want to see a path to healthy unit economics. The Rule of 40 is a quick diagnostic, not gospel: it ignores factors like customer concentration risk, market conditions, and strategic investments. But it is a useful mental model for founders and investors to assess whether a company's growth-profitability balance makes sense.
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Related Glossary Terms
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Further Reading
The Burn Multiple: Why Capital Efficiency Is the New Growth
The burn multiple has replaced growth rate as the metric investors scrutinise most. This guide explains the formula, stage-specific benchmarks, and why every dollar of burn should be creating an intangible asset that compounds in value.
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