The Hidden Metrics Amazon Sellers Ignore — And Why They’re Costing You Thousands

Most Amazon sellers obsess over one metric: ACOS.

And don’t get me wrong—Advertising Cost of Sale is important. It helps you understand how efficient your ad campaigns are. But here’s the brutal truth:

ACOS only tells you how well your ads are doing, not how well your business is performing.

If your entire Amazon strategy is built around lowering ACOS, you’re playing checkers while your competition plays chess.

At Weavos, we manage brands doing 6, 7, and 8 figures annually on Amazon. And we’ve seen firsthand: the top sellers—the ones scaling fast and profitably—track an entirely different set of metrics.

In this post, we’ll break down five underrated but critical metrics you need to monitor weekly, plus how to implement them in your business without spreadsheet overwhelm.

1. Contribution Margin per Unit

Let’s start with the most financially dangerous blind spot on Amazon: profit per unit after everything.

Why it matters

Many sellers mistakenly assume their gross profit margin or ROAS gives them enough insight into profitability. But on Amazon, your costs stack up quickly:

• FBA fees

• Pick and pack fees

• Referral fees

• Advertising

• Returns

• Inbound shipping

• Coupons/Promotions

  
  

You may have a healthy-looking ACOS of 20%, but if you’re making $0.80 profit per unit after everything else… you’re not building a sustainable business.

True contribution margin = Selling Price - (COGS + FBA fees + Ad Spend + Returns + Inbound Freight)

Real-world example

Let’s say you sell a $35 product. Here’s how the math might look:

Cost Component	Amount
COGS	$10.00
Amazon FBA + Referral	$8.50
Ad Spend (20% ACOS)	$7.00
Returns + Defects	$1.50
Freight + Packaging	$1.20
Net Contribution Margin	$6.80

Now imagine your ad costs creep up or you offer a 10% off coupon—your margin drops to $3 or less.

Action Steps:

• Create a SKU-level margin calculator and update it monthly.

• Factor in return rate, coupon usage, and freight per unit.

• Don’t scale ads unless your contribution margin is strong.

2. Inventory Turn Rate

Also known as sell-through rate, this metric tells you how quickly you’re moving inventory out of Amazon warehouses.

Why it matters

Amazon loves sellers who move inventory efficiently. It’s good for them, and it’s good for you. A high inventory turn rate leads to:

• Better IPI scores

• Lower storage fees

• Higher ranking potential (Amazon rewards products that convert quickly)

If you’re moving slowly—especially on new product launches—Amazon’s algorithm may de-prioritize your listing organically.

Amazon tracks how many units you sell per week relative to how much inventory you have in stock. If it thinks your product isn’t moving, it assumes it’s irrelevant or overpriced.

Benchmarks

Turn Rate (Avg. Days of Inventory)	Health Rating
0–30 Days	Very Healthy
31–60 Days	Healthy
61–90 Days	Caution
90+ Days	Problematic

Action Steps:

• Track inventory turnover monthly by SKU.

• Set alerts at 60 days to consider liquidating or promo pushing.

• Use Amazon’s “Manage Excess Inventory” tab as an early warning system.

3. Keyword Rank Volatility (Not Just Rank)

This is where most sellers get lazy: they look at a static keyword rank and feel good.

But volatility is the true threat.

Why it matters

A keyword that sits at rank #7 for a month is gold. A keyword that jumps between #7 and #40 each week is chaos.

Amazon’s algorithm responds to consistent sales velocity. If your listing has high volatility in search rank, you’re at risk of:

• Losing page 1 placement

• Needing to overcompensate with ads

• Being vulnerable to competitor takeovers

  
  

What causes volatility?

• Inconsistent sales or low inventory

• Aggressive competition with stronger promotions

• Price fluctuations or buy box loss

• Out-of-stock situations

The best brands we manage don’t just aim for “page one.” They aim for stable, predictable presence on high-converting keywords.

Action Steps:

• Use Helium 10 Keyword Tracker or DataDive to chart rank over time

• Monitor fluctuations daily during launches and major promotions

• Identify patterns (e.g., weekends dropping off = conversion rate issue)

4. Buy Box Suppression Rate

You might think, “I’m the only seller, I have the Buy Box.”

Not so fast.

Amazon can suppress the Buy Box even if you’re the only seller—usually due to pricing, delivery time, or listing health.

Why it matters

When the Buy Box is suppressed, your listing is live… but not buyable with one click. That kills your conversion rate and tanks your PPC.

We’ve seen 60%+ drops in conversion just from temporary buy box suppression—even when nothing changed on the listing visually.

Common causes:

• Amazon’s algorithm thinks your price is uncompetitive

• Drastic pricing changes (up or down)

• Inconsistent delivery times or long lead times

• Inventory performance issues

Action Steps:

• Use Seller Central’s “Buy Box Eligibility” report weekly

• Monitor pricing relative to recent history (not just competitors)

• Keep restock timelines tight to avoid slow delivery flags

5. TACOS Trendline (Total Advertising Cost of Sale)

This one gets ignored far too often—but it’s one of the most telling metrics of long-term growth.

Why it matters

ACOS only tracks ad spend vs. ad revenue. TACOS tracks ad spend vs. total revenue, including organic.

TACOS = Ad Spend / Total Revenue

A growing brand with declining TACOS is a winning brand. It means your paid traffic is feeding organic sales.

But a flat ACOS and rising TACOS? That means you’re just burning cash to stand still.

Example:

Month	Ad Spend	Ad Revenue	Organic Revenue	Total Revenue	ACOS	TACOS
Jan	$3,000	$9,000	$6,000	$15,000	33%	20%
Feb	$3,200	$9,000	$5,500	$14,500	35%	22%
Mar	$3,400	$9,000	$5,000	$14,000	38%	24%

The ad efficiency (ACOS) looks okay, but your overall dependence on ads is increasing, not decreasing. That’s a red flag.

Action Steps:

• Track 30-day rolling TACOS trends by SKU and portfolio

• Break out brand-new ASINs separately (they’ll naturally have higher TACOS)

• Use this trendline to know when to scale spend or pause for optimization

Bonus Metric: Amazon Session-to-Conversion Rate

If you’re seeing traffic but not sales, this is your canary in the coal mine.

A healthy listing should convert at 15–25% for most categories.

If you're below 10%, you likely have issues with:

• Main image not driving clicks

• Price not competitive

• Poor review rating or review count

• A+ content or title not reinforcing value

• Buy Box suppression

  
  

Action Steps:

• Go into Business Reports > Detail Page Sales and Traffic

• Look at “Sessions” vs “Unit Session Percentage”

• Run A/B tests on main image, title, and price before changing keywords or ads

How to Track All of This Without a Full-Time Analyst

Let’s be honest—most brand owners don’t have time to do all this every week. That’s why we recommend building a Weekly Amazon KPI Dashboard.

You can do this in Google Sheets or Notion. Here’s what to include:

Metric	Frequency	Tool to Use
Contribution Margin	Weekly	Custom Calculator
Inventory Turn Rate	Weekly	Amazon Reports / SoStocked
Keyword Rank Volatility	Daily	Helium 10, DataDive
Buy Box Eligibility	Weekly	Seller Central
TACOS Trendline	Weekly	Amazon Ad Console
Conversion Rate	Weekly	Business Reports

Final Thought: ACOS is Not Enough

It’s easy to get tunnel vision on Amazon.

But the sellers who win in 2025 and beyond will be the ones who:

• Treat their Amazon account like a real business

• Track the right metrics (not just the easy ones)

• Make decisions based on profit, not guesswork

It’s not about working harder. It’s about measuring smarter.