Rule of 40 vs Burn Multiple: Key Differences Explained

The Rule of 40 is a SaaS health benchmark: a company's annual revenue growth rate (%) plus its EBITDA or FCF margin (%) should sum to 40% or higher. Example: 60% growth + –20% profit margin = 40. Or 30% growth + 10% profit margin = 40. Both achieve the Rule of 40. The rule was popularized by Brad Feld and became a standard benchmark for evaluating whether a company has the right balance between investing in growth and maintaining financial discipline. Companies above 40 are considered healthy regardless of whether they're profitable. Rule of 40 is most useful for growth-stage companies ($10–100M ARR) where the market expects both growth and a credible path to profitability. Below 40 is a yellow flag; well below 40 suggests either insufficient growth or unsustainable burn. Two computation notes keep the metric honest. Use the same period for both inputs — trailing-twelve-month growth against TTM margin, or forward against forward — and pick one profit definition (EBITDA margin or free-cash-flow margin) and hold it constant. FCF margin is the harder test because it captures working capital and capitalized costs that EBITDA forgives. Some public-market investors quote a weighted variant that rewards growth over margin, but the plain sum remains the board-deck standard.

The Burn Multiple, popularized by David Sacks, measures how much cash a company burns for every dollar of net new ARR it generates. Formula: Net Burn ÷ Net New ARR. A burn multiple of 1.0 means you spend $1 to add $1 of ARR. A burn multiple of 2.0 means you spend $2 for every $1 of ARR added. Lower is better. Benchmarks: under 1.0 is exceptional, 1–1.5 is good, 1.5–2.0 is acceptable, above 2.0 is concerning, above 3.0 is a crisis. Burn Multiple is especially useful for pre-Rule-of-40 companies (under $10M ARR) where growth rates are high but margins don't yet matter — it keeps focus on capital efficiency when the denominator (ARR) is still small. Compute it on net numbers on both sides: net burn (operating cash out minus cash in, excluding financing) over net new ARR (new plus expansion, minus churn and contraction). Gross new ARR flatters the metric badly for leaky businesses — a company adding $4M gross while churning $2M has a true denominator of $2M, and its real burn multiple is double the flattering version. Quarterly is the standard measurement window, and the trend across quarters carries more information than any single print.

Use Burn Multiple when you're early (seed–Series B) and the key question is capital efficiency. Use Rule of 40 when you're later stage and investors expect a balanced growth/profitability equation. The best founders track both — Burn Multiple keeps you honest about efficiency when ARR is small, and Rule of 40 gives you a target as you scale. There is also a fundraising-narrative angle. Burn multiple is the number a seed or Series A investor will compute from your own deck whether you present it or not — net burn and net new ARR are both on the page. Presenting it yourself, with the quarter-over-quarter trend, signals you manage the business on efficiency rather than discovering it in diligence. Rule of 40 earns a slide only once revenue is large enough that margin is a choice rather than a foregone conclusion.

A Series B SaaS company has $30M ARR, growing 70% YoY, with a –25% EBITDA margin. Rule of 40 score: 70 – 25 = 45. Above 40 — healthy. Their Burn Multiple last quarter: net burn of $4M, net new ARR of $3M = 1.33x. That's good. Both metrics paint a consistent picture: strong growth with acceptable capital efficiency. If their Rule of 40 dropped to 35 (60% growth, –25% margin), they'd need to either grow faster or cut burn. If Burn Multiple rose to 2.5x, they'd investigate whether sales productivity or payback period has deteriorated. Run one company through both metrics at two stages. Year one: ARR grows from $4M to $8M — 100% growth — on $6M of net burn, so burn multiple = $6M ÷ $4M of net new ARR = 1.50x, solidly acceptable at that stage. Rule of 40 on the same year: 100% growth plus an EBITDA margin around −100% (roughly $6M of burn against roughly $6M of recognized revenue) sums to about 0 — a catastrophic-looking score that is flatly misleading, which is exactly why nobody applies Rule of 40 at $4M ARR. Year five: the same company at $40M ARR grows 40%, adding $16M of net new ARR, with a +5% FCF margin. Rule of 40 = 40 + 5 = 45 — healthy. Burn multiple is now zero or negative, since there is no net burn, so it has stopped carrying information. The metrics never disagreed; they each have a domain, and the company crossed from one into the other.