Most ad accounts inherit their target ROAS and target CPA without ever validating them — set too aggressively, they choke volume; set too loosely, they bleed profit. The core argument: a target ROAS isn't an optimization setting, it's a business decision.
Start with the minimum acceptable target based on profit margin:
Use your effective margin — one that accounts for returns, shipping, and fees — not headline gross margin. A 40% gross margin with a 25% return rate works out to roughly 30% effective margin, which shifts break-even ROAS from 250% to 333%.
Next, decide how much of that margin the business will reinvest in acquisition — the acquisition share (PAR):
With a 40% margin and a 50% acquisition share, target ROAS comes out to 500%. That conversation, the article argues, is "the single most consequential number nobody on the account ever discusses." Research from George Michie suggests an optimal acquisition-share range of 50–70%, with 60–70% often maximizing profit.
Compare the desired target against what the auction can actually deliver:
If your target is 500% ROAS but the achievable figure is 300%, the gap tells you exactly what needs to improve: conversion rate, CPC, or average order value.
Use the Google Ads bid simulator to find where incremental returns fall below break-even. Calculate incremental ROAS at each simulator step by dividing extra conversion value by extra spend — tighten below break-even, and recognize you're leaving profit on the table if you're sitting far above it.
Targets deserve an annual review with whoever owns the P&L, while bid simulator checks should happen weekly. One overlooked point: if your sales team's lead-to-sale conversion rate is cut in half, your target CPA is cut in half too — meaning sales performance directly constrains what your ad account can spend. For help auditing your account's targets, explore Best Partner's services or get in touch.
Break-even ROAS = 1 / profit margin. Use your effective margin — accounting for returns, shipping, and fees — not headline gross margin; a 40% gross margin with 25% returns works out to roughly 30% effective margin.
It's the portion of profit margin a business reinvests in acquisition. Research suggests an optimal range of 50–70%, with 60–70% often maximizing profit.
Calculate achievable ROAS as (conversion rate × average order value) / CPC, then compare it to your target. The gap shows whether you need to improve conversion rate, CPC, or order value.
The target itself should be revisited annually with the P&L owner, while granular checks using the bid simulator should be run weekly.
To apply what you just read to your own site, start with a free audit of where things are now.
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