High ACoS is the single most common complaint we hear from Amazon sellers. The instinct is always the same: lower bids until the number comes down. But cutting bids blindly usually cuts sales faster than it cuts cost — and your ACoS barely moves. Lowering ACoS the right way is about structure, data, and fixing the things underneath your ads. Here’s how we approach it for the brands we manage.

First, know your break-even ACoS

You can’t set a target until you know the number that matters: your break-even ACoS. This is the point where an ad-driven sale makes zero profit. The formula is simple:

Break-even ACoS = Profit margin before ad spend (%)

If your product sells for $40 and your total cost (product, Amazon fees, shipping) is $28, your profit before ads is $12 — a 30% margin. That means your break-even ACoS is 30%. Anything below 30% is profitable; anything above it is losing money on that sale. Most sellers chasing a “low ACoS” don’t actually know this number, so they either over-cut and lose ranking, or tolerate spend that’s quietly unprofitable.

Separate branded and non-branded keywords

This is the mistake we see most often. When your brand-name keywords sit in the same campaign as your generic keywords, the very low ACoS of your branded terms (people searching your brand already intend to buy) masks the high ACoS of everything else. You think the campaign is healthy at 20% — but your non-branded keywords might be running at 45% while branded props up the average. Split them into separate campaigns so you can see, and control, what’s actually profitable.

Fix the listing before you touch the bids

This is where most sellers waste months. They try to fix ACoS by adjusting bids and budgets, but the real problem is the listing the ad sends people to. If your conversion rate is low, every click costs you more to convert — so ACoS stays high no matter how you bid. A clean title, strong main image, benefit-led bullets, and A+ content do more for ACoS than any bid tweak, because they raise conversion rate across every keyword at once. We always audit the listing first. A 1% lift in conversion rate can cut your effective cost per sale by 15–20% without changing a single bid.

Mine your search term report for negatives

Every week, pull your search term report and look for terms eating spend without converting. These are your negative keywords. A product targeting “stainless steel water bottle” might be showing for “plastic water bottle” — clicks, no sales, wasted budget. Adding consistent negatives is one of the fastest, safest ways to bring ACoS down, because you’re cutting pure waste rather than cutting winners.

Promote proven converters into exact match

When a keyword in a broad or phrase campaign proves it converts, give it focused attention: move it into an exact-match campaign where you control the bid precisely. You’re taking the terms Amazon has already shown convert for your product and concentrating budget where it works, instead of letting it leak across loosely matched searches.

Adjust bids by placement

Amazon lets you modify bids by placement — top of search, product pages, and rest of search. Check your placement report. If top of search converts at 15% but product pages convert at 3%, raise your top-of-search modifier and lower the product-page bids. This shifts spend toward what actually sells.

The bigger picture: TACoS, not just ACoS

Chasing the lowest possible ACoS can actually hurt you. Some higher-ACoS upper-funnel spend lifts total sales and organic ranking, which lowers your TACoS (total advertising cost of sales) over time. The goal isn’t the lowest ACoS — it’s the right ACoS for each product at its stage, while organic momentum builds underneath. New launches can run a high ACoS on purpose; mature products should run tight.

Where most sellers get stuck

Doing all of this consistently — weekly search-term reviews, placement analysis, campaign restructuring, and listing optimization — is a real time commitment, and it’s easy to make it worse by reacting to noise instead of trends. That’s exactly the work we do for the brands we manage as an Amazon SPN-certified partner.

Want to know where your ad spend is leaking?

We’ll audit your account for free and show you exactly which campaigns and keywords are draining budget, and what to fix first. Get your free Amazon audit →