Amazon Advertising ROI: What Matters | Marknology

If you're running Amazon ads and only looking at ROAS, you're measuring the wrong thing.

ROAS (Return on Ad Spend) is the metric everyone talks about. It's clean, it's simple, and it makes you feel good when the number is high. "We're getting $5 back for every $1 we spend on ads!" Sounds great in a board meeting.

But ROAS is a vanity metric. It doesn't tell you if your ads are actually profitable. It doesn't account for organic sales lift. It doesn't factor in customer lifetime value. And it definitely doesn't help you make smart decisions about where to allocate budget.

I've been managing Amazon advertising since 2015. I've overseen millions in ad spend across hundreds of brands. And the single biggest mistake I see brands make is optimizing for the wrong metrics.

Here's what actually matters when measuring Amazon advertising ROI.

Why ROAS Alone Is Misleading

ROAS measures how much revenue you generate for every dollar spent on ads. If you spend $1,000 on ads and generate $5,000 in attributed sales, your ROAS is 5x.

Sounds good, right? Except:

ROAS doesn't account for your margin. A 5x ROAS on a product with 60% margins is wildly profitable. A 5x ROAS on a product with 15% margins might be losing you money once you factor in Amazon fees, fulfillment, and the cost of goods.

ROAS doesn't show organic lift. When you run ads, you improve your organic ranking. Better ranking drives organic sales. If you turn off ads to "save money," your organic sales drop too. ROAS only measures the direct attributed sales, not the halo effect.

ROAS incentivizes the wrong behavior. If you optimize purely for ROAS, you'll end up only advertising on your branded terms (where ROAS is always high) and pulling back on category terms (where ROAS is lower but you're actually acquiring new customers). You'll have great ROAS and no growth.

ROAS is easily gamed. Want to double your ROAS overnight? Cut your bids in half. You'll spend less and your attributed sales will drop, but not proportionally. Your ROAS goes up. Did you actually improve anything? No. You just made the number look better.

ROAS has its place. It's useful for comparing campaign performance. But it's not the metric you optimize for.

TACoS: The Metric That Actually Matters

TACoS stands for Total Advertising Cost of Sale. It's the percentage of your total Amazon revenue (organic plus paid) that you spend on advertising.

If you did $100,000 in total sales last month and spent $15,000 on ads, your TACoS is 15%.

TACoS is a better metric than ROAS because it accounts for the full picture. It shows you what percentage of your business you're spending to drive all sales, not just the ones Amazon attributes to ads.

Here's why TACoS matters:

It shows advertising efficiency in context. A brand with 10% TACoS is more efficient than a brand with 25% TACoS, assuming similar margins. It means they're driving more total sales per ad dollar spent.

It captures organic lift. If your TACoS is steady but your total sales are growing, your ads are working. You're driving awareness, improving ranking, and generating organic sales on top of the paid ones.

It aligns with profitability. You can set a TACoS target based on your margin structure and know that hitting it means you're profitable. If your margins are 40% and you're spending 15% on ads, you know you have 25% left for everything else.

It prevents the wrong optimization. If you cut ad spend and TACoS goes down but total sales also go down, you know you over-corrected. TACoS keeps you honest about the relationship between ads and total business performance.

The Total Amazon ROI Framework

If you really want to measure Amazon advertising ROI correctly, you need to think beyond just the ads themselves. You need a framework that accounts for the full customer journey and business impact.

Here's the framework we use at Marknology:

1. Direct Attributed Sales

This is the sales Amazon directly attributes to your ads. It's the baseline. Track it by campaign type (Sponsored Products, Sponsored Brands, Sponsored Display) and by keyword theme (branded, category, competitor).

2. Organic Sales Lift

When you run ads, your organic ranking improves. Better ranking drives organic sales. To measure this, compare your organic sales in periods when you're advertising versus periods when you're not. The delta is your organic lift.

This is harder to measure precisely, but you can approximate it. Look at total sales minus attributed ad sales. If that number goes up when you increase ad spend and down when you decrease it, your ads are driving organic lift.

3. Brand Halo Effect

Some customers click your ad, don't buy immediately, but come back later and buy a different product or buy without clicking an ad again. Amazon's attribution window is limited (7 days for click, 1 day for view). But real customer behavior extends beyond that.

Track new-to-brand customers. If you're acquiring new customers through ads and those customers are buying multiple products over time, that's the halo effect in action.

4. Lifetime Value (LTV)

If you're selling consumables, subscriptions, or products with high repeat rates, a customer acquired through ads today might be worth 3x their initial purchase over the next 12 months.

Calculate LTV by looking at repeat purchase rates and average order frequency. Then factor that into your acceptable Customer Acquisition Cost (CAC).

5. Total Business Profitability

At the end of the day, ROI is about profit, not revenue. You need to know:

• Revenue (total Amazon sales)
• COGS (Cost of Goods Sold)
• Amazon fees (referral fees, FBA fees)
• Ad spend
• Everything else (shipping to Amazon, storage, returns, etc.)

What's left is profit. If your profit is growing while ad spend is steady or decreasing as a percentage of revenue, your advertising is working.

How to Calculate True CAC on Amazon

Customer Acquisition Cost (CAC) is one of the most important metrics in any business. On Amazon, it's tricky to calculate because Amazon doesn't give you clean data on new versus repeat customers.

Here's how we do it:

Step 1: Identify new-to-brand sales. Amazon Brand Analytics shows new-to-brand metrics. This tells you how many customers bought from you for the first time.

Step 2: Allocate ad spend to new-to-brand. If 40% of your sales are new-to-brand, assume roughly 40% of your ad spend is going toward acquisition (the rest is retention or brand defense).

Step 3: Divide ad spend by new customers. If you spent $10,000 on ads and acquired 200 new-to-brand customers, your CAC is $50.

Step 4: Compare to LTV. If your average customer is worth $150 over their lifetime, a $50 CAC is fantastic. If they're worth $60, you're barely profitable. If they're worth $40, you're losing money on acquisition.

This isn't perfect, but it's directionally accurate. And it gives you a way to think about advertising as an investment in customer acquisition, not just a cost center.

LTV Considerations for Subscription and Repeat Products

If you're selling supplements, pet food, beauty products, or anything consumable, LTV changes everything.

A customer who buys once and never comes back is worth their initial purchase. A customer who subscribes or buys every 30 days for a year is worth 12x that.

When you factor in LTV, you can afford to pay more for acquisition. You can run ads at break-even or even a small loss on the first purchase because you know the payback happens over time.

Here's what to track:

Subscribe & Save adoption rate. What percentage of customers subscribe versus one-time purchase? Higher is better.

Repeat purchase rate. For non-subscription products, what percentage of customers buy again within 90 days? Within 180 days?

Average order frequency. How many times does the average customer buy per year?

Retention rate. What percentage of subscribers stay subscribed after 3 months? 6 months? 12 months?

Once you have these numbers, you can calculate LTV:

LTV = (Average Order Value) x (Purchase Frequency per Year) x (Average Customer Lifespan in Years)

Then compare to CAC. The LTV:CAC ratio should be at least 3:1 for a healthy business. If it's lower, you're either spending too much on acquisition or not retaining customers well enough.

When Losing Money on Ads Is Actually Winning

This sounds counterintuitive, but there are situations where running ads at a loss is the right move.

During product launch. The first 30 to 90 days of a product's life on Amazon are critical. You need reviews, you need ranking, you need momentum. Running ads aggressively (even at break-even or a small loss) during launch sets you up for long-term profitability.

When defending market share. If a competitor is bidding on your branded terms or launching a similar product, you might need to increase ad spend to defend your position. Short-term pain, long-term gain.

When acquiring high-LTV customers. If you know a customer acquired through ads will be worth $500 over two years, paying $100 to acquire them (even if the first purchase is only $50) is smart.

When building brand awareness in a new category. If you're expanding into a new product line or category, ads are part of the cost of entry. You're not just driving sales, you're building presence.

The key is knowing the difference between strategic losses and stupid ones. Strategic losses are time-bound, data-informed, and have a clear payback mechanism. Stupid losses are just burning money because you don't know what else to do.

New Managed Commerce (NMC) Model Impact on ROI

Amazon's shift to the New Managed Commerce (NMC) model in 2024 changed how attribution works. Under NMC, Amazon gives more credit to top-of-funnel touchpoints (Sponsored Display, Sponsored Brands video) instead of just last-click attribution.

This is good for brands because it more accurately reflects how customers actually shop. Someone might see your Sponsored Brands video ad, not click, but search for you later and buy. Under the old model, that sale looked organic. Under NMC, the video ad gets some credit.

What this means for ROI measurement:

Your attributed sales will look higher. NMC captures more of the customer journey, so you'll see more sales attributed to ads. This doesn't mean your ads are suddenly more effective; it just means Amazon is measuring them better.

You need to adjust your benchmarks. If your ACoS was 20% under the old model and it jumps to 25% under NMC, that's not necessarily worse performance. You're just seeing a fuller picture.

Top-of-funnel ads are more valuable. Sponsored Display and Sponsored Brands video used to look inefficient because they rarely got last-click credit. Under NMC, they're more accurately valued, which means you should probably invest more in them.

The shift to NMC makes Amazon advertising measurement more complex, but also more accurate. If you were already thinking about the full funnel, NMC helps you prove what you already knew: awareness drives sales, even if the path isn't linear.

How Marknology Reports ROI to Clients

Transparency is non-negotiable. If you're paying an agency to manage your ads, you should know exactly what's happening and whether it's working.

Here's what we include in our monthly reports:

Total sales (organic + paid). The full picture, not just attributed sales.

Ad spend and TACoS. What we spent and what percentage of total revenue that represents.

ACoS by campaign type. Sponsored Products, Sponsored Brands, Sponsored Display broken out separately so you can see what's working.

New-to-brand metrics. How many new customers we acquired and at what cost.

Search term performance. What keywords are driving sales, what's wasting budget, what we're testing.

Creative tests. If we tested new images, A+ content, or video, we show the performance delta.

Strategic recommendations. What we're going to do next month and why.

We don't hide behind "proprietary dashboards" or summary metrics. You get the raw data, the analysis, and the plan. If something's not working, we tell you. If we screwed up, we own it.

This level of transparency isn't standard in the industry, but it should be. You're paying for results, not mystique.

The Metrics You Should Track Weekly

You don't need to obsess over data every day, but you should have a weekly check-in on the metrics that matter.

Total sales (7-day rolling average). Is the trend up, down, or flat?

TACoS. Is it within your target range? If not, why?

ACoS by campaign type. Are any campaigns way out of range?

Inventory levels. Are you going to run out of stock? Stock-outs kill momentum and waste all the ranking you've built through ads.

Top 10 search terms. What's driving sales? What's new? What's dying?

New product performance. If you launched something recently, is it trending the right direction?

Weekly reviews keep you close enough to the data to catch problems early without drowning in daily noise.

The Metrics You Should Review Monthly

Monthly is when you zoom out and look for patterns.

Month-over-month growth. Total sales, organic sales, ad-attributed sales. What's the trend?

TACoS trend. Is it improving (going down) or getting worse (going up)?

New-to-brand acquisition. Are you bringing in new customers or just selling to the same people?

Product mix. What's growing? What's declining? Should you shift ad budget?

Profitability. After all costs (COGS, fees, ads, fulfillment), are you making money?

Monthly reviews are where strategy gets adjusted. If something's not working, this is when you kill it or fix it.

When to Hire an Agency to Manage Amazon Advertising

You don't need an agency if you're spending $500 a month on ads and have the time to manage it yourself. But there are clear signals that you've outgrown the DIY model.

You're spending $5,000+ per month on ads. At this level, small optimizations are worth hundreds of dollars. An agency pays for itself in found money.

You don't know if your ads are profitable. If you can't confidently explain your unit economics and how ads fit into them, you need help.

You're too busy to optimize weekly. Amazon ads require active management. If you're checking in once a month, you're leaving money on the table.

You're launching new products regularly. Launch strategy is high-leverage. An agency that's done it hundreds of times knows how to avoid costly mistakes.

You want to scale but don't know how. Going from $50K to $100K per month requires different strategies than going from $10K to $50K. Experience matters.

A good agency doesn't just manage your ads. They think about how ads fit into your total Amazon strategy, how to balance growth and profitability, and how to set you up for long-term success.

The Bottom Line

Measuring Amazon advertising ROI is more art than science. Amazon doesn't give you perfect data. Customer journeys are messy. Attribution is imperfect.

But you don't need perfect data. You need directionally accurate data and a framework for making decisions.

Track TACoS, not just ROAS. Measure total sales, not just attributed sales. Factor in LTV. Understand your unit economics. Know the difference between strategic investment and wasteful spending.

And if you're not sure whether your ads are working, ask someone who's done this a few hundred times. That's what we're here for.

FAQ

What's a good ACoS for Amazon ads?

It depends on your margins. If your margins are 40%, an ACoS of 25% leaves you with 15% for other costs. A good ACoS is one that keeps you profitable. Typical range is 15% to 35%, but category and business model matter.

What's the difference between ACoS and TACoS?

ACoS is ad spend divided by ad-attributed sales. TACoS is ad spend divided by total sales (organic + paid). TACoS gives you the full picture of advertising efficiency.

How much should I spend on Amazon ads?

Start with 10% to 15% of your revenue goal. If you want to do $50K in sales, budget $5K to $7.5K for ads. Adjust based on performance and profitability.

Should I run Sponsored Products, Sponsored Brands, or Sponsored Display?

All three, eventually. Start with Sponsored Products (highest ROI). Add Sponsored Brands when you have budget and want to build awareness. Add Sponsored Display for retargeting and top-of-funnel reach.

How long does it take for Amazon ads to work?

You'll see immediate sales from ads, but it takes 30 to 60 days to dial in targeting and bids. Real momentum (organic ranking lift, sustained growth) takes 90 days.

Can I run Amazon ads myself or do I need an agency?

If you're spending less than $5K/month and have time to learn, DIY is fine. Above that, an agency usually pays for itself in saved time and better optimization.

What's a good TACoS percentage?

15% to 25% is typical for established brands. New brands might run 30% to 40% during launch. The right TACoS depends on your margin structure and growth goals.