C4 · Economics & metrics · model-dependent

Rule of X

Also: Rule of X

Definition. Rule of X is X × growth percentage points + FCF-margin percentage points. Bessemer’s January 2024 article proposed context-dependent growth weights around 2 for private and 2–3 for public cloud companies. Those historical valuation associations do not identify the causal return to growth spending or establish a current coefficient.

historical valuation heuristic; current coefficients and causal interpretations are unverified Last updated 2026-06-18 Source: Bessemer Venture Partners, The Rule of X, January 2024, https://www.bvp.com/atlas/the-rule-of-x. Older practitioner analysis; no current calibration or universal score threshold is asserted.

Formula

Rule of X model-dependent

R_{X} = X g_{%} + FCF margin_{%}

Plain English: Rule of X score = X × stated annual growth % + FCF margin %

Notation: RoX = X×g_% + FCF_margin_%; disclose X, its source date, sample and growth convention

Benchmark by stage

Source: Bessemer Venture Partners, The Rule of X, January 2024, https://www.bvp.com/atlas/the-rule-of-x. Older practitioner analysis; no current calibration or universal score threshold is asserted.

Stage	Rule of X	Notes
Illustrative scenario: X=2	g=20%, FCF=0% → 40	Arithmetic example only; 40 is not a universal Rule of X hurdle.
Illustrative scenario: X=2	g=30%, FCF=0% → 60	Growth coefficient is a declared historical scenario, not a current fitted value.
Illustrative scenario: X=2	g=40%, FCF=0% → 80	High score does not remove cash, contribution or financing constraints.
Coefficient sensitivity	g=30%, FCF=0%, X=3 → 90	Changing X changes the ranking and level; compare only disclosed definitions.

Naive vs corrected

Version	Formula
Naive	Calling a historical fitted or chosen growth weight a current universal coefficient, or transferring the Rule of 40 threshold without justification.
Corrected	State the growth basis, FCF definition, coefficient, market sample and date. A historical regression coefficient ratio is an association sensitive to specification and regime. Treat a chosen X as a scenario; use current evidence before claiming calibration.

Common errors

Presenting X≈2 as verified for the current market
Using 40 as a universal Rule of X threshold
Interpreting valuation correlation as causal value from additional spend
Comparing ARR-growth and recognized-revenue-growth variants without disclosure
Ignoring cash runway, service costs, dilution or uncertainty because the score is high

Where this sits

Part of the Economics & metrics (C4) cluster in the GTM World Model. Related to the model's "RoX=X×g_%+FCF_%. If a specified valuation regression has coefficients a for growth and b for margin, X=a/b when b≠0 is a sample- and specification-dependent association, not an investment-response coefficient." equation.

rule of 40 →arr →burn multiple →magic number →

How to cite this

@misc{shalvi_gtm_metric_rule_of_x_2026,
  author = {Singh, Shalvi},
  title  = {Rule of X — GTM World Model Metrics},
  year   = {2026},
  url    = {https://shalvisingh.com/gtm/metrics/rule-of-x}
}

Singh, Shalvi. "Rule of X — GTM World Model Metrics." shalvisingh.com, 2026. https://shalvisingh.com/gtm/metrics/rule-of-x