ACOS stands for "Advertising Cost of Sales" on Amazon. It shows how much you spend on advertising compared to the sales generated, indicating the profitability of your ad campaigns.

A lower ACOS is generally better, but there is no single benchmark number that applies to all campaigns or brands. The ideal ACOS depends on factors such as product types, campaign goals, and the maturity of the products.

Generally speaking, if your ad spend is lower than your profit (after expenses and fees), you're making money, and you know how much you have left to spend on ads. For example, if you spend £5 on advertising and earn £100 for the entire month, your ACOS may look good, but you could have improved your business even more by investing more.

There are cases where a high ACOS is not necessarily a bad thing:

• During a launch period
• During a peak season period
• When liquidating inventory
• When trying to dominate a niche

In these cases, a heavy upfront investment can provide long-term advantages.

Additionally, ACOS should be paired with another metric called TACOS (Total Ads Cost of Sales). TACOS takes into account not only sales from ads but also organic sales that could result from the overall advertising's halo effect.

Top tips to optimize ACOS:

• Optimize your listing page (clear and accurate titles, bullet points, descriptions, at least 15-20 reviews with 3.5+ star ratings, sufficient inventory, consistent sales, and good stock inventory).
• Conduct in-depth keyword research and experiment and optimize your keywords, removing negative keywords
• Continuously explore what works best.
• Prioritize your top-selling items.
• Try sponsored display product targeting options.
• Try sponsored brands keyword targeting.
• Test for at least 2 weeks before optimization.