Metrics & KPIs

CAC

Customer Acquisition Cost — total spend required to acquire one new paying customer, including ads, agency fees, and creative production.

CAC is what it actually costs to acquire a paying customer, including not just ad spend but also agency fees, creative production, influencer payments, and any tools dedicated to acquisition. Most beginners conflate CAC with CPA, but they diverge: CPA includes returning customers (cheaper), while CAC is specifically new-customer cost.

CAC is only meaningful in context. A $40 CAC is disastrous for a $35 one-time product but a bargain for a subscription that does $180 LTV. The metric you actually watch is LTV/CAC ratio (see LTV).

Watch how CAC trends over time as you scale. Audiences fatigue, best-performing creatives burn out, and CAC creeps up quietly. Operators who only look at daily spend miss the slow bleed until it's already broken their unit economics.

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Related terms in Metrics & KPIs
AOV
Average Order Value — the average dollar amount a customer spends per transaction. Total revenue divided by number of orders.
AOV Lift
The increase in Average Order Value produced by a specific tactic — bundles, upsells, order bumps, quantity discounts. Every dollar of AOV lift compounds against ad spend.
ATC
Add to Cart — the tracked event when a visitor adds an item to their cart. ATC-to-purchase ratio is a powerful diagnostic of checkout friction.
Attach Rate
The percentage of orders that include a secondary item — typically an upsell, bundle, or order bump. Every 10% of attach rate is ~4-6% of AOV lift.
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