SaaS Magic Number Calculator

The SaaS Magic Number measures how much new annual recurring revenue each dollar of sales and marketing buys. You take the ARR you added this quarter — current-quarter ARR minus prior-quarter ARR — and divide it by the sales and marketing you spent the previousquarter. The prior-quarter spend matters: revenue lags the spend that generated it, so pairing this quarter's growth with last quarter's spend is the honest read on efficiency. A Magic Number of 1.0 means every $1 of S&M returned $1 of net-new ARR within roughly a year.

Because it uses ARR directly, this version needs no annualization. If you prefer to work from quarterly revenue rather than ARR, multiply the quarter-over-quarter revenue gain by four before dividing. Not sure your acquisition math holds up? Cross-check with the CAC Calculator and Payback Period Calculator.

0.75 is the line most operators use to decide whether to keep spending. The bands around it:

The Magic Number is a top-down, quarterly read on the whole go-to-market engine — it does not need customer counts or churn assumptions, just ARR and spend. That makes it fast, but coarse. CAC payback period tells you how many months a single customer takes to repay their acquisition cost, and LTV:CAC tells you whether the lifetime value justifies that cost at all. None of the three says where the inefficiency sits — your win rateseparates "we do not create enough opportunities" from "we do not close the ones we have", which have very different fixes.

Read them together. A strong Magic Number with a long payback period usually means expansion revenue is doing the heavy lifting; a weak Magic Number with healthy LTV:CAC often points to a spend-timing or ramp problem rather than a broken funnel. Pair the Magic Number with your growth rate to see whether efficient spend is actually translating into durable growth.

The Magic Number answers the question that comes right before a funding decision: is my go-to-market efficient enough to responsibly spend more? When your Magic Number sits at 0.75 or above, the math says additional S&M should return proportional net-new ARR — the constraint is cash, not efficiency. That is exactly the moment non-dilutive capital does its best work: you fund another quarter of proven sales and marketing and repay it from the revenue that growth produces, instead of selling equity to finance a motion you already know works.

Founderpath provides revenue-based financing to bootstrapped SaaS founders — capital to scale an efficient go-to-market without dilution, board seats, or loss of control. Model the equity you would keep with the Equity Dilution Calculator, and score the specific hire or campaign you are about to fund with the SaaS ROI Calculator.