Derive your target CPC from the advertising goal, not from a feeling.

Every bid you place on Amazon is implicitly a statement about what you want the spend to achieve. Most of the time that statement is unconscious — the bid was set "because Amazon suggested it" — and unconscious goals are how accounts burn budget. This episode is about making the goal explicit and deriving the CPC from it.

The four goal categories

Almost every PPC objective on Amazon collapses to one of four shapes (the next four episodes go deep on each):

1. Reach — impressions and visibility.
2. Clicks — click volume and click-through rate.
3. Units / Revenue — orders and sales.
4. Profitable — orders at or under a contribution-margin target.

Each one produces a different target CPC for the same keyword on the same ASIN. Without naming the goal first, you cannot defend the bid.

The general formula

For a goal expressed as a target ACOS (advertising cost of sale), the maximum profitable CPC is:

max CPC = ASP × CVR × target ACOS

Where ASP is the average selling price (after promotions and coupons but before referral fees), CVR is the realised conversion rate on the keyword, and target ACOS is the fraction of revenue you are willing to spend on advertising.

A worked example

Say your product sells for €25 (ASP), the keyword "ergonomic kitchen scale" converts at 9 % for your ASIN, and your target ACOS is 25 %.

max CPC = €25 × 0.09 × 0.25 = €0.56

Bid above €0.56 and the keyword is unprofitable at that ACOS target. Bid below it and you are leaving volume on the table. The number is precise; the inputs are not, which is why we re-derive it monthly.

What about contribution margin?

ACOS measures spend against revenue. Margin-driven targets measure spend against contribution margin (revenue minus Amazon fees, FBA fees, landed COGS, returns). For products with high fees and thin margin, the right formula is:

max CPC = ASP × CVR × (CM% − target profit%)

Where CM% is contribution margin as a fraction of revenue and target profit% is the margin you want left after ad spend. This is the version we use for mature ASINs.

What about goals that aren't profit?

Launches don't want profit; they want rank. Brand defence doesn't want profit; it wants impression share against your own brand keyword. Conquesting wants share of a competitor's impression voice. Each of those has its own derivation, and each one produces a higher CPC than the profit-driven target. That is fine — provided the goal is named, the time horizon is bounded, and the budget for the "investment" period is ring-fenced.

Episodes 12–16 walk through each of these goal types and their CPC derivations in detail. Episode 12 picks up with the simplest of them: reach.