SaaS Magic Number
A sales efficiency metric measuring how much new recurring revenue a company generates per dollar of sales and marketing spend.
The magic number compares the growth in annualized recurring revenue during a quarter to the sales and marketing spend from the prior quarter (accounting for the lag between spend and resulting revenue), producing a single ratio for sales efficiency. It's used specifically to judge whether a company should be investing more aggressively in sales and marketing or pulling back.
A magic number above roughly 0.75-1.0 generally suggests the sales and marketing engine is efficient enough to justify accelerating investment; well below that suggests spend isn't converting to growth efficiently and increasing it further would be premature.
The magic number is the go/no-go gauge for scaling sales. Before a company doubles its sales team, investors check whether the current team earns its keep. Unlike CAC payback, which measures cash timing, the magic number measures growth yield per dollar of sales and marketing — the more direct input to the 'should we spend more' decision.
Compute it on net new ARR — new customers plus expansion, minus churn and contraction — not gross bookings. Excluding churn makes a leaky go-to-market engine look better than it is.
It's a quarterly ratio, so one big enterprise deal can spike it. Look at the trailing four-quarter trend, and treat the common thresholds as tripwires rather than laws.
Magic number = (current quarter ARR - prior quarter ARR) x 4 / prior quarter sales and marketing spendARR grows from $8M to $9M quarter over quarter (a $1M increase), and the prior quarter's sales and marketing spend was $3.2M. Magic number = ($1M x 4) / $3.2M = 1.25, suggesting an efficient sales engine worth investing further behind.
Use the magic number as a go/no-go signal before ramping sales headcount aggressively — a company scaling its sales team ahead of a magic number consistently above 0.75 is usually burning cash faster than the growth it's buying justifies.
What magic number justifies increasing sales investment?
A commonly cited threshold is 0.75 or above, with figures approaching or exceeding 1.0 considered a strong signal to accelerate sales and marketing spend further.
How is the magic number different from CAC payback?
Both look at sales and marketing spend. CAC payback asks how many months of gross profit it takes to recover acquisition cost — a cash-timing question. The magic number asks how much annualized new revenue each dollar produced — a growth-yield question.
Why does the magic number use last quarter's sales and marketing spend?
Because of the sales lag: money spent this quarter mostly produces revenue next quarter, so matching prior-quarter spend to this quarter's growth gives a fairer read.
What does a low magic number look like?
Hypothetically, $1M of quarterly ARR growth against $8M of prior-quarter sales and marketing spend gives ($1M x 4) / $8M = 0.5 — a sign to fix the funnel before adding headcount.
Related terms
Run the numbers yourself: dilution, SAFE conversion, and fund-returner calculators.