What is ACoS and how is it calculated?

ACoS stands for "Advertising Cost of Sales." The metric shows you what percentage of your ad-driven revenue you spent on advertising itself. The formula is simple:

ACoS formula

ACoS = (ad spend / ad revenue) x 100

Example: You spent $50 on advertising and generated $250 in revenue from it. Your ACoS is (50 / 250) x 100 = 20%.

An ACoS of 20% means that for every dollar of revenue your ads generated, 20 cents went toward advertising costs. The lower the ACoS, the more efficiently your campaign is working. But "lower" isn't automatically "better," as you'll see in a moment.

The components of the ACoS formula

ACoS is influenced by three factors:

  • Cost per click (CPC): How much you pay per click. Higher CPCs push the ACoS up.
  • Conversion rate (CR): How many clicks turn into a purchase. A higher conversion rate lowers the ACoS.
  • Average selling price (ASP): A higher selling price lowers the ACoS at the same click cost.

This yields an alternative, deeper formula: ACoS = CPC / (CR x ASP). This formula shows you exactly which levers you can pull to move your ACoS.

What is a good ACoS?

The honest answer: there is no universally "good" ACoS. The right ACoS depends on your profit margin, your product's stage and your business goals.

Benchmarks by industry and product type

Product situation Typical ACoS Assessment
Established product, high margin 10 to 20% Profitable
Established product, medium margin 15 to 25% Solid
New product, launch phase 30 to 60% Acceptable (temporarily)
Low-price product (under $15) 25 to 40% Hard to lower
High-price product (over $100) 8 to 15% Often achievable

These figures are averages and vary depending on category and competitive intensity. More important than an industry comparison is your individual break-even ACoS.

Calculating the break-even ACoS

The break-even ACoS is the ACoS value at which your advertising makes neither a profit nor a loss. Anything below it is profitable; anything above it costs you money. The calculation is based on your profit margin before advertising costs.

Break-even ACoS formula

Break-even ACoS = profit margin before advertising costs (in %)

Put differently: your break-even ACoS equals the percentage of your selling price that remains as profit after deducting all costs (except advertising costs).

Worked example: determining the break-even ACoS

Let's take a concrete product with a selling price of $29.99:

Item Amount
Selling price $29.99
Purchase price / manufacturing cost -$7.00
Shipping to the Amazon warehouse -$1.50
Amazon selling fee (15%) -$4.50
FBA fulfillment fee -$4.49
Other costs (packaging, returns) -$1.50
Profit before advertising costs $11.00

The profit margin before advertising costs is: 11.00 / 29.99 = 36.7%. That means your break-even ACoS is 36.7%. As long as your ACoS stays below 36.7%, you make money on every order generated through advertising.

Setting your target ACoS

The break-even ACoS tells you where you stop making a loss. Your target ACoS should sit below that so you're actually profitable. How far below depends on your strategy.

Three strategic approaches

  • Profit maximization: Your target ACoS is well below break-even. Example: break-even at 36%, target ACoS at 20%. You earn more per order but generate fewer orders because you bid more conservatively.
  • Growth and ranking: Your target ACoS is just below or even right at break-even. You reinvest most of your margin into advertising to build market share and organic ranking.
  • Aggressive launch: Your target ACoS is deliberately above break-even. You accept short-term losses to quickly build sales history and rank organically. You should keep this strategy time-limited.
Practical tip

Calculate your break-even ACoS individually for each product. Products with different purchase prices, selling prices and FBA fees have different break-even points. A blanket target ACoS for all products means you'll be needlessly conservative on some and lose money on others.

Why is my ACoS so high? The most common causes

A high ACoS always has one or more concrete causes. Here are the most common reasons you should check systematically.

1. Irrelevant keywords burn through budget

Your campaign is serving ads for search terms that don't match your product. Clicks come in, but conversions don't follow. This happens especially with automatic campaigns and broad match keywords that have no negative keywords.

2. Bids that are too high

If your CPC is too high relative to the selling price, even a good conversion rate can't save the ACoS. Worked example: at a CPC of $1.50, a selling price of $15 and a CR of 10%, you get an ACoS of 100%. You either need to lower the CPC or improve the CR.

3. A weak listing

Your listing doesn't convert well enough. The most common causes: a poor main image, an unattractive price, missing or weak reviews, generic bullet points. Every improvement in conversion rate has a direct effect on the ACoS.

4. The wrong campaign structure

If you bundle too many different products into one campaign, underperforming products can eat up the budget of your strong ones. Split products with different performance into separate campaigns.

5. No regular optimization

Campaigns that are set up once and then forgotten almost always see a rising ACoS. The market changes, new competitors appear, and search terms shift. Without regular adjustment, you become less efficient.

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8 proven strategies to lower your ACoS

Here are eight concrete measures that demonstrably improve ACoS. Work through them in order and prioritize the ones that give you the biggest lever in your case.

Strategy 1: Use negative keywords consistently

Analyze your search term report and identify search terms that generate clicks but no conversions. Add these as negative keywords. This is the fastest and most effective way to lower your ACoS. Do it at least once a week.

Strategy 2: Pause or scale back unprofitable keywords

Keywords with an ACoS that stays consistently above your break-even and can't be improved through optimization should either be paused or have their bids cut significantly. Not every keyword can be made profitable. Accept that and don't waste budget on it.

Strategy 3: Adjust bids based on performance

Lower bids for high-ACoS keywords gradually (10 to 15% per adjustment). Raise bids for keywords with a low ACoS and good conversion rate to increase their visibility. This ongoing bid optimization is one of the most important levers.

Strategy 4: Use exact match keywords for top performers

Identify your 10 to 20 best keywords (lowest ACoS, most conversions) and build a separate exact match campaign for them. Exact match gives you the most control and prevents your budget from being spent on irrelevant variations.

Strategy 5: Improve your listing conversion rate

Improving the conversion rate from 10% to 12% lowers your ACoS by 16.7% without changing anything in your campaigns. Invest in better images, rework your bullet points and actively grow your review count. The lever is enormous.

Strategy 6: Use bid adjustments for placements

Top-of-search placements often have the highest conversion rate. If you find that your ads convert better in "top of search" than in other placements, you can set a bid adjustment of 20 to 50% for that placement and lower the base bid accordingly. This concentrates your budget on the most profitable placement.

Strategy 7: Use dayparting

Not every time of day delivers the same conversion rate. If you find that clicks in the early morning or late evening never convert, you can focus your budget specifically on the high-revenue hours. Tools like Sellantica enable automatic dayparting.

Strategy 8: Rework your campaign structure

Separate high- and low-performing products into distinct campaigns. Build a clear structure with separate campaigns for Auto, Broad, Phrase and Exact. This gives you maximum control over budget allocation and bid management.

Practical tip

Prioritize the strategies by their expected lever. Setting negative keywords and pausing unprofitable keywords often deliver the fastest results. Listing optimization has the biggest long-term effect. Don't work on all eight strategies at once; focus on 2 to 3 and measure the impact.

ACoS vs. TACoS: why ACoS alone isn't enough

ACoS only shows you how efficient your ad spend is. It doesn't account for how much organic revenue your product generates. That's why ACoS can be misleading.

A concrete scenario

Your product does $10,000 in total revenue per month. Of that, $4,000 comes through PPC and $6,000 through organic sales. Your ad spend is $1,200.

  • ACoS: 1,200 / 4,000 = 30%
  • TACoS: 1,200 / 10,000 = 12%

Viewed in isolation, an ACoS of 30% looks high. But the TACoS of 12% shows that your advertising costs only a small part of total revenue. The PPC campaign is likely also driving organic sales by improving ranking.

That's why you should never look at ACoS in isolation. Always watch the TACoS and the development of your organic sales alongside your advertising efforts.

Measuring and documenting improvements

ACoS optimization is a continuous process. To determine whether your measures are working, you need clean tracking.

What you should document

  • Weekly ACoS: Log each campaign's ACoS weekly in a spreadsheet. This lets you spot trends and seasonal patterns.
  • Change log: Note every change you make to a campaign (date, what was changed, why). This lets you trace the impact of individual measures.
  • Break-even ACoS: Update your break-even ACoS whenever prices or costs change. An outdated break-even leads to wrong decisions.
  • TACoS trend: Watch the TACoS over weeks and months. A falling TACoS with stable or rising total revenue is the best sign of a healthy PPC strategy.

Realistic timeframes for improvements

Don't expect miracles overnight. Here are realistic timeframes:

  • Setting negative keywords: impact visible within 1 to 2 weeks
  • Bid adjustments: 1 to 3 weeks until a stable new ACoS
  • Listing optimization: 2 to 4 weeks until the improved CR noticeably lowers the ACoS
  • Campaign structure rebuild: 4 to 8 weeks until the new structure settles in
Important

ACoS naturally fluctuates from day to day and week to week. Always evaluate your performance over a period of at least 7 days, ideally 14. Individual daily values aren't meaningful and lead to rash decisions.

Conclusion: ACoS as a tool, not an obsession

ACoS is an important metric, but it's not the only one that matters. A low ACoS at the expense of visibility and growth is no success. A temporarily high ACoS during a product launch can be exactly the right strategy.

Calculate your break-even ACoS carefully, set your target ACoS based on your business strategy, and then work systematically on the levers. The eight strategies in this article give you a concrete roadmap. And don't forget: always watch the TACoS as a complement to the ACoS so you keep the full picture of your profitability in view.