Magic number

Formula

Net new ARR / prior-quarter S&M spend

Unit

ratio

Models

SaaS

What it is

The Magic Number measures how efficiently a SaaS company converts sales and marketing spend into new recurring revenue. It is calculated as net new ARR in a quarter divided by prior-quarter sales and marketing spend.

How to calculate it

Take the ARR added in the current quarter (new ARR minus churned ARR, i.e., net new ARR), then divide by the total sales and marketing expense from the prior quarter. A ratio above 1.0 means every dollar of S&M spend generated more than a dollar of annualized new revenue.

Why it matters

The Magic Number acts as a go-to-market efficiency signal for SaaS businesses. It tells investors and operators whether it is worth accelerating sales and marketing investment: above 1.0 is a green light to pour in capital, 0.5–1.0 signals the model works but inefficiently, and below 0.5 suggests fundamental issues with GTM fit or product-market fit.

Benchmarks & pitfalls

Scale Venture Partners and KBCM (2024) define the interpretive thresholds as: >1.0 = pour money in; 0.5–1.0 = inefficient; <0.5 = model not figured out. The KBCM 2024 private-SaaS median sits at approximately 0.7, meaning most companies fall in the "inefficient" zone. A key variant pitfall is whether to use gross new ARR or net new ARR in the numerator — net new ARR (subtracting churn) is the more conservative and meaningful version. S&M expense timing also matters: some practitioners lag by one quarter, others use the same-quarter spend.