Growth
Net revenue retention before new logos.
A 5-point NRR improvement often outperforms a quarter of new-logo bookings and costs a fraction. Expansion is the highest-leverage growth input for Rule of 40.
§ Resource — Capital & Intelligence
The Rule of 40 for SaaS — a board-ready guide.
The Rule of 40 is the single number boards and investors use to reconcile growth against cash efficiency. It compresses two of the three inputs to SaaS valuation into a comparable score — and drives more of the multiple at a capital event than growth rate alone.
The calculation.
Revenue growth plus profitability margin, on a trailing basis. The definition of "profitability" is the part that gets litigated in diligence — pick one and stay with it.
ARR growth (YoY)28%Ending ARR ÷ prior-year ending ARR − 1
Adjusted EBITDA margin14%Adjusted EBITDA ÷ revenue (LTM)
Rule of 40 score42%Sum of the two — target ≥ 40%
Institutional convention: ARR growth (or GAAP revenue growth for audited companies) plus adjusted EBITDA margin. Free cash flow margin is the stricter alternative and is preferred by growth-equity buyers past ~$50M ARR.
How to read the score.
- 01< 20%Sub-scaleBelow public-SaaS median; discounted at capital events.
- 0220 – 40%BuildingInvestors accept it with a credible path back above 40%.
- 0340 – 60%InstitutionalWhere premium multiples begin. Board default target.
- 04> 60%Top decileRare. Usually growth-led (>40%) with real EBITDA.
Why boards weight it at capital events.
At a raise, secondary, or sale, buyers price the business against a public comp set. The correlation between forward revenue multiple and Rule of 40 has been tighter than the correlation to growth rate alone for most of the last decade. That means the score is not a vanity metric — it is the axis a diligence model rotates around.
A board that walks into a process with a 42% score and a clean audit trail behind both terms is a fundamentally different conversation from a board that walks in with 55% growth, negative 30% EBITDA, and a hand-wave on the path to break-even.
Levers that actually move the score.
Growth
Cut low-fit segments, don't just add pipeline.
Segments with weak retention drag both variables. Removing them lifts growth quality and margin at the same time.
Margin
Reprice hosting and infra before headcount.
Cloud commitments, storage tiering, and per-seat pricing on downstream tools usually free 200–400 bps of margin without touching the plan.
Margin
Shift S&M mix toward payback discipline.
Cap channels at a target CAC payback rather than a spend ceiling. Cash margin improves without capping growth capacity.
Definition
Fix the metric definition before the next raise.
Board packs that switch between GAAP EBITDA, adjusted EBITDA, and FCF margin lose credibility. Pick one, document it, and hold it across every cycle.
Common pitfalls.
- Mixing bookings growth with revenue-based margin — inflates the score by a full cycle.
- Excluding stock-based compensation from adjusted EBITDA without disclosing it.
- Treating one strong quarter as the trend — Rule of 40 is a trailing metric, not a snapshot.
- Optimising the score by starving R&D. Buyers discount it once the pattern is visible.
For an audit-grade calculation surface — trailing Rule of 40, NRR, CAC payback, and Magic Number wired to a single assumptions sheet — start from the SaaS financial model template. For live board packs and diligence-ready reporting, see mandates.
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