How to Lower Amazon PPC ACOS

Step 1: Know Your Break-even ACOS First

Before you optimize anything, calculate your break-even ACOS. This is the maximum ACOS where you still break even on each sale. The formula is:

Break-even ACOS = (Profit Before Ads ÷ Selling Price) × 100

If you sell a product for $29.99 and your total costs (COGS, FBA fees, shipping) are $18.00, your profit before ads is $11.99. Your break-even ACOS is ($11.99 / $29.99) × 100 = 40%. Any campaign running above 40% is losing money. Any campaign below it is profitable. Write this number down—it is the benchmark every decision below builds on.

Step 2: Harvest Converting Search Terms into Exact Match

Run a search term report weekly. Look for search terms in your auto and broad-match campaigns that have generated at least 2–3 sales at an ACOS below your target. Move those terms into a dedicated exact-match campaign with a bid you control. This isolates your best-performing traffic and lets you bid more aggressively on terms you know convert.

A typical result: a broad-match campaign running at 35% ACOS often contains individual search terms converting at 15–20% ACOS. Pulling those into exact match and adding them as negative exact in the original campaign immediately improves both campaigns.

Step 3: Add Negative Keywords Aggressively

Most sellers add negatives reactively. Be proactive. In your search term report, negate any term that has spent more than 2x your target cost-per-sale without converting. If your average order value is $25 and your target ACOS is 25%, your target cost-per-sale is $6.25. Negate any search term that has spent $12.50 or more with zero sales.

• Phrase negatives for broad irrelevant themes (e.g., "wholesale," "bulk," "free").
• Exact negatives for specific terms that look relevant but do not convert for your product.

Step 4: Improve Your Listing to Boost Conversion Rate

ACOS is a function of CPC and conversion rate. If you double your conversion rate at the same CPC, your ACOS drops by half. Focus on:

• Main image: test a cleaner background, larger product in frame, or different angle. Main image changes alone can shift conversion rate by 10–30%.
• Price competitiveness: check what the top 3 competitors charge. A product priced 15% above the category average will convert worse on the same clicks.
• Reviews: if you have fewer than 15 reviews, every new review has an outsized impact on buyer trust and conversion.
• Bullet points: lead with the benefit, not the feature. "Keeps drinks cold for 24 hours" converts better than "double-wall vacuum insulation."

Step 5: Daypart Your Campaigns

Not every hour of the day converts equally. Download your hourly performance data (available via the Amazon Ads API or third-party tools) and look for patterns. Many categories see conversion rates drop 30–50% between midnight and 6 AM while CPCs stay similar. Use bid adjustments or budget scheduling to reduce spend during low-converting hours. Even a modest shift—cutting bids 40% from midnight to 5 AM—can drop overall ACOS by 3–5 points.

Step 6: Separate Branded and Non-branded Campaigns

If your brand name generates any search volume, create a dedicated branded campaign. Brand searches typically convert at 2–5x the rate of generic searches and run at very low ACOS (often 5–10%). Mixing them into the same campaign as generic terms inflates your reported ACOS for generic terms and masks the true cost of discovery advertising. Separate them so you can set distinct budgets and bids for each.

Step 7: Reduce Bids on High-ACOS, Low-Volume Keywords

Sort your keywords by ACOS descending. Many sellers find a long tail of keywords spending $5–$15/week each at 60–100% ACOS. Individually they seem small, but collectively they can account for 20–30% of total spend. For any keyword above your break-even ACOS with fewer than 5 sales in the last 30 days, cut the bid by 25–40%. If performance does not improve after two weeks, pause it entirely.