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A Guide to Ecommerce Metrics

A Guide to Ecommerce Metrics

Last Updated:  
June 13, 2024

You’ve probably stared at acronyms in your data analytics tool for hours. But to make sure we’re on the same page, let’s refresh what the key metrics that make up ROAS are, how they’re calculated, and how they all work together to determine your ROI.

What is ROAS (Return on Ad Spend)?

ROAS tells you how much money you’re making for every dollar invested in advertising. It helps you to  understand the profitability of your marketing efforts and make informed decisions about budget allocation and optimization.

Here’s the formula to calculate ROAS: Total revenue generated / total advertising spend = ROAS

Example: $5,000 / $1,000 = 5

A higher ROAS indicates that your advertising is more effective at driving revenue, while a lower ROAS suggests that you may need to optimize your campaigns to improve profitability.

What is CPM (cost per thousand impressions)?

CPM describes the cost of 1,000 ad impressions. An ad impression is counted each time your ad is displayed, regardless of whether it’s clicked or not. CPM is commonly used in online display advertising, where you pay based on the number of times your ad is shown to potential customers.

Here’s the formula to calculate CPM: Total spend per ad campaign / total impressions generated = CPM

Example: $500 / 100,000 impressions = $5

A lower CPM indicates that you’re paying less for each ad exposure, while a higher CPM suggests that you’re reaching a more targeted or valuable audience. But that doesn’t always mean you should aim for a lower CPM, particularly if delivering ads to a more “expensive” audience can result in more conversions and higher average order value (AOV).

What is CTR (click-through rate)?

CTR measures the percentage of people who click on your ad after seeing it. It indicates how engaging and relevant your ad is to your target audience.

Here’s the formula to calculate CTR: (Number of clicks received per ad / impressions generated) * 100 = CTR

Example: (100 clicks / 10,000 impressions) * 100 = 1%

A high CTR suggests that your ad is effectively capturing attention and encouraging people to take action, while a low CTR may indicate that your ad is not resonating with your audience. The average CTR varies by industry and ad platform, but a good rule of thumb is to aim for a CTR above 1%.

It’s also important to note that platforms like Google and Meta use CTR as a factor in determining your ad’s quality score and relevance, which can influence your ad’s visibility and cost per click (CPC).

What is CPC (cost per click)?

CPC tracks how much you pay each time someone clicks on your ad. It’s a popular pricing model for search engine advertising (like Google) and social media advertising (like Meta). CPC allows you to only pay for the actual clicks your ad receives, rather than paying for impressions or other engagement metrics.

Here’s the formula to calculate CPC: Total cost of ad campaign / number of clicks received = CPC

Example: $100 / 50 clicks = $2

Like CTR, CPC directly impacts the cost of acquiring new customers. A lower CPC means that you’re paying less for each click, which can help you stretch your advertising budget further.

However, it’s important to balance CPC with other metrics like conversion rate to ensure that the clicks you’re paying for are actually translating into meaningful actions like purchases or sign-ups. This could mean accepting a higher CPC if serving your ads to an audience that’s more expensive to reach translates into more conversions.

What is CVR (conversion rate)?

CVR calculates the percentage of people who take a desired action after interacting with your ad or website, like making a purchase, filling out a form, or signing up for a newsletter. This indicates how effectively your advertising and website are turning visitors into customers.

To calculate CVR, you divide the number of conversions by the total number of ad interactions (such as clicks or impressions), then multiply by 100 to express it as a percentage. For example, if your ad generates 100 clicks and 10 conversions, your CVR would be 10% (10 / 100 x 100 = 10%).

Here’s the formula to calculate CVR: (Number of conversions / total number of ad interactions, like clicks or impressions) * 100 = CVR

Example: (10 conversions / 100 clicks) * 100 = 10%

CVR directly impacts the revenue generated from your advertising efforts. A higher CVR means that more of the people interacting with your ads are taking meaningful actions that contribute to your bottom line. The average CVR varies widely by industry and ad platform, but a good benchmark is to aim for a CVR above 2%.

What is CPA (cost per acquisition)?

Cost per acquisition (CPA), also known as cost per action or cost per conversion, measures how much you pay to acquire a new customer or conversion. It’s a key indicator of the cost-effectiveness of your advertising efforts in driving specific, valuable actions like purchases or sign-ups.

Here’s the formula to calculate CPA: Total cost of ad campaign / Number of acquisitions it generates = CPA

Example: $1,000 / 50 conversions = $20

CPA reflects the cost of driving meaningful business results from your advertising. A lower CPA means that you’re paying less to acquire each new customer or conversion, which can help you achieve a higher ROI. However, it’s important to balance CPA with other metrics like average order value (AOV) and customer lifetime value (CLV) to ensure that the customers you’re acquiring are actually profitable for your business.

What is AOV (average order value)?

AOV calculates the average amount of money spent by a customer each time they place an order on your website or app. This metric evaluates your customers’ purchasing behavior and your business’s overall health.

Here’s the formula to calculate AOV: Total revenue generated over a specific period / number of orders placed during that same period = AOV

Example: $10,000 in May / 100 orders in May = $100

AOV affects the revenue generated from each customer acquisition. A higher AOV means that customers are spending more money per transaction, which can help you generate more revenue and achieve a better return on your advertising investment.

How These Metrics Work Together to Determine Your ROI

Understanding the interplay of metrics from top to bottom of the marketing funnel is essential for optimizing ROI.  Let's take a top-to-bottom approach to see how these metrics interact:

CPM and CPC: These metrics start at the top of the funnel. CPM measures the cost for every thousand ad impressions, setting the stage for ad visibility. CPC, which is the cost for each click on your ad, can be improved with a high Click-Through Rate (CTR), indicating engaging and relevant ads. Better CTR not only lowers CPC but also drives qualified traffic to your site.

CVR and CPA: Deeper in the funnel, Conversion Rate (CVR) measures the percentage of clicks that result in conversions, indicating effective ad targeting and compelling calls to action. Cost Per Acquisition (CPA) integrates the costs of clicks and their conversion effectiveness, showing the overall cost to acquire a customer.

ROAS and AOV: At the bottom of the funnel, Return on Ad Spend (ROAS) reflects the revenue earned per dollar spent on advertising, closely tied to Average Order Value (AOV). AOV tells you how much customers spend per transaction, influencing ROAS. For instance, if CPA decreases but AOV increases, ROAS might decrease less dramatically, illustrating the delicate balance between these metrics.

By examining these metrics in order from CPM to ROAS, marketers can better understand how top-of-funnel activities (like ad impressions and clicks) cascade through the funnel to affect bottom-line outcomes like sales and revenue. This structured approach not only clarifies the direct and indirect impacts of each metric but also aids in strategic decision-making to optimize each stage of the marketing funnel for better ROI.

What is Marketing Efficiency Ratio (MER)?

A great way to evaluate how well your marketing strategy or campaigns perform overall is with the Marketing Efficiency Ratio (MER). 

MER = total revenue / total ad spend

Example: if total revenue generated from your last campaign was $20,000, but the ad spend was $10,000: MER = 20,000 / 10,000 = 2

Since MER is expressed as a ratio, we report this as: 2.0.

You might think this sounds a lot like ROAS, but there’s some differences. ROAS returns how much money you make for every dollar spent on ads. On the other hand, MER takes all of the effects of your marketing efforts from ad spend to determine the efficiency of your campaigns. 

What is a Good Marketing Efficiency Benchmark?

The ideal MER value will depend on the industry, but anything above 3.0 is recommended to aim for. When it comes to ecommerce businesses, there are a lot of costs involved in producing goods, and therefore you’d expect to see higher MER values on average (so anything above 5.0 or above is considered a good number). 

The money spent on advertising will impact revenue on a daily basis, and it’s a great metric to follow to keep an eye on how your business is performing. 

Marketing Efficiency Ratio Use Cases


MER is a metric you can use as your north star when you’re lost in the sea of attribution (you knew a pun was coming).

Whether you’re uncertain of Facebook’s ability to drive revenue to your business or not, you can view your MER at any given time to best understand the effectiveness of your paid media.

If you’re operating below your MER goal, you can cut back spend on the platforms you’re least confident in or launch new ads.

Either way, you know the effectiveness of your current paid media is degrading.


Jan 1 hits and your CEO tells you and your team that we want to shoot for $10M in revenue this year. And based on all of the data, you can do that profitably with a 5 MER (or a marketing spend equal to 20% of your revenue goal). You now know that you need to build your paid media strategy with a $2M war chest.

Or say you just scored a new client and they want to hit $100k in revenue next month. They have a $200 Mode AOV, (don’t know what Mode AOV is; check out 3 Amigos of AOV).

Before we can calculate a Target MER we have to do some maths:

Revenue Goal/AOV = $100,000/$200 = ~ 500 Orders

Great! Now we know we need 500 orders next month to hit our target. Next, we looked at the data and surmised a CPA of $30 is a reasonable goal. The client agrees.

Finally, we calculate the budget (almost there):

Total Ad Spend = Orders * CPA = 500*$30 = $15,000

Dope. Now we know the Total Revenue and Total Ad Spend.

Time to calculate our target MER.

Target MER = $100,000/$15,000 = 6.67

Learn how brands easily calculate and optimize MER with Triple Whale.

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