--- title: SaaS Magic Number — definition | RGM® Glossary url: https://realgrowthmatters.com/glossary/magic-number/ updated: 2026-06-10 source_html: https://realgrowthmatters.com/glossary/magic-number/ --- # SaaS Magic Number mag·ic num·bernoun Spend a dollar on go-to-market this quarter, collect this much new ARR next — above one means step on the gas. Term : SaaS Magic Number Origin : Scale Venture Partners / Lars Leckie (2008-era) Formula : Net new ARR ÷ prior-period S&M spend Read : >0.75 invest more; <0.5 fix the engine ## Forms & parts of speech magic number · noun The lagged GTM-efficiency ratio. "The **magic number** is 1.1 — sales efficiency says pour more in, not less." ## Definition in plain terms The magic number measures sales-and-marketing efficiency: the net new ARR a company adds in a period, divided by the sales-and-marketing spend of the PRIOR period (the lag reflects that go-to-market spend takes a quarter or two to convert). A magic number of 1.0 means every dollar of S&M spend produced a dollar of new annual recurring revenue — a strong signal to invest more. ## The mechanics Reading bands: above ~0.75 the engine is efficient enough to feed harder; 0.5-0.75 is workable but watch it; below 0.5 the go-to-market motion is broken and pouring in more spend just burns faster. The lag is the metric's craft — using same-period spend overstates efficiency, so the prior quarter's (or the trailing average) is the honest denominator. Its blind spots: it ignores retention quality (new ARR that churns flatters the number temporarily), gross-margin differences, and the difference between new-logo and expansion ARR — so it screens GTM efficiency, then the cohort and retention work explains it. ## When it matters The magic number is the 'should we spend more or less on growth?' instrument — the cleanest read on whether the sales-and-marketing engine deserves more fuel. It pairs with CAC payback (the per-customer view of the same question) and the burn multiple (the whole-company view). For marketers it's the number that converts 'give us more budget' into evidence: a magic number above 1 makes the case automatically; below 0.5, no budget argument survives until the engine's fixed. **Worked example.** A SaaS team requests a 50% budget increase on the strength of growth. The CFO runs the magic number: net new ARR last quarter ($3M) over S&M spend the quarter before ($5M) = 0.6 — workable but not a green light. The conditional answer: budget rises only for the two channels whose isolated magic numbers clear 1.0, while the sub-0.4 channels get fixed or cut first. Two quarters later the blended magic number hits 0.9, the full increase lands on evidence, and growth accelerates without the burn the original blanket ask would have caused. **Failure modes to watch.** Using same-period spend (overstates efficiency); reading a high number built on ARR that's about to churn; treating it as whole-company efficiency (it's only S&M); and scaling spend below 0.5 because the chart still points up. ## Synonyms & antonyms ### Synonyms magic numberSaaS magic numbersales efficiency ratio ### Antonyms unmeasured GTM spendburn multiple (the whole-company view) ## Origin & history Originated in the SaaS-investing community of the late 2000s — commonly attributed to Scale Venture Partners (Lars Leckie's writing popularized the 'magic number' name around 2008) as public SaaS companies' earnings disclosures made the sales-efficiency calculation reproducible; it became a standard board metric. Etymology: [source](https://www.scalevp.com/). ## Usage trends Search interest for this term over the last five years: [View interest-over-time on Google Trends →](https://trends.google.com/trends/explore?q=saas%20magic%20number&date=today%205-y) ## Common questions What is the SaaS magic number? : Net new ARR divided by prior-period sales-and-marketing spend — go-to-market efficiency, lagged. What's a good magic number? : Above ~0.75 supports investing more; 0.5-0.75 is workable; below 0.5 signals a broken engine. Why the lag? : Sales-and-marketing spend takes a quarter or more to convert — using prior-period spend in the denominator keeps the ratio honest. ## Related tools & calculators - tool[CAC calculator](/tools/cac-calculator/) - tool[LTV-to-CAC ratio](/tools/ltv-to-cac-ratio-calculator/) ## Resources & people to follow - referenceScale Venture Partners — the magic-number origin - referenceDavid Skok / forEntrepreneurs — SaaS efficiency metrics - referenceRGM analysis — lag the denominator or it flatters Curated, non-competitor resources verified per term. ## Related training - module[Marketing analytics](/training/marketing-analytics/) ## Disciplines Areas of marketing where saas magic number is a core concern: [Measurement](/training/marketing-analytics/)[Growth strategy](/training/growth-marketing-foundations/) ## Read next ## Related terms [Burn multiple](/glossary/burn-multiple/)[Rule of 40](/glossary/rule-of-40/)[CAC payback period](/glossary/cac-payback-period/)[CAC](/glossary/cac/)[ARR](/glossary/arr/) ## Sources 1. trends[Google Trends — "saas magic number"](https://trends.google.com/trends/explore?q=saas%20magic%20number&date=today%205-y)