Marketing dashboards throw a dozen acronyms at you, but four metrics carry most of the weight: ROAS, conversion rate, CAC and LTV. Understand how they connect and you can tell, quickly, whether an ad channel is building your business or quietly draining it.
ROAS: the headline number (and its trap)
Return on ad spend is revenue ÷ ad spend. A 4× ROAS means $1 of ads produced $4 of revenue. The trap: ROAS measures revenue, not profit. If your product costs $3 to make and sells for $4, that "great" 4× ROAS is actually a loss. Always check ROAS against your margins — the ROAS calculator shows the profit left after ad spend, not just the ratio.
Conversion rate: where the money leaks
You pay for clicks, but you earn from conversions. Conversion rate (conversions ÷ visitors) is the efficiency of everything after the click. Doubling a 1% rate to 2% doubles revenue from the same ad budget — often cheaper than buying more traffic. Measure it with the conversion rate calculator.
CAC: what a customer actually costs
Customer acquisition cost is total spend ÷ new customers won. It ties ad spend and conversion rate together: cheap clicks with a terrible conversion rate can still produce an expensive CAC. CAC only means something when you compare it to what a customer is worth — which brings us to the last metric.
LTV: what a customer is worth
Lifetime value is the total profit a customer brings over the whole relationship — average purchase × frequency × margin × how many years they stay. LTV sets the ceiling on what you can afford to pay to acquire someone. Estimate it with the customer lifetime value calculator.
The ratio that ties it together: LTV:CAC
The single most important number in paid growth is the LTV:CAC ratio. A widely used benchmark is 3:1 — earn three dollars of lifetime value for every dollar spent acquiring a customer. Below 1:1 you lose money on every sale; far above 3:1 and you may be leaving growth on the table by under-spending. A high ROAS with a poor LTV:CAC is a warning sign, not a win.
Don't forget reach: CPM
At the top of the funnel, CPM (cost per 1,000 impressions) is how you compare the raw price of reach across channels. Cheap CPMs on the wrong audience are no bargain, but on equal targeting, CPM keeps ad buys honest — the CPM calculator puts any two campaigns on the same basis.
Putting it together
Read them as a chain: CPM buys reach, conversion rate turns reach into customers, CAC is the resulting cost, and LTV is the payoff. ROAS is a useful daily gauge, but the LTV:CAC ratio is the metric that tells you whether the whole machine makes money. And before you scale, know your break-even point so you spend from profit, not hope.