How much can you actually pay to acquire a customer?
The most you can spend on acquisition is not a feeling. It's your contribution margin per order times your target payback, bounded by an LTV:CAC ceiling. Take the lower of the two. Answer a few questions and get your number, with both legs of the math shown.
How max allowable CAC is calculated
Two legs, take the lower. The payback leg: contribution margin per order times the months of payback you will accept. The LTV leg: gross-margin LTV divided by your target LTV:CAC ratio (3:1 is the standard). Whichever leg is lower is your ceiling, and the result shows which one is binding so you know which lever raises it.
The 3:1 guardrail is measured on gross-margin LTV, not revenue LTV, because you cannot spend revenue you never keep. Your AOV and margin carry into the conversion revenue-leak calculator, and the DTC profitability calculator rebuilds the P&L this ceiling depends on. All eleven free DTC calculators share these benchmarks.