Top 10 KPIs for Email Marketing

Melanie Balke
December 22, 2021

I’m going to take a stab in the dark here and make an assumption: if you’re here, reading this blog, then I think it’s fairly safe to assume you’re looking for some email marketing tips! I bet you’re super excited to learn all about this amazing marketing channel, and I’m excited to teach you about it!

That’s why I’m always updating my blog with amazing tips, tricks, and strategies: to amplify your brand’s email marketing efforts. I’ve already covered plenty of topics, — from finding the perfect email marketing agency and interactive emails to holiday marketing and Klaviyo basics — now it’s time to talk about… (drum roll, please!)

A black-and-white photo of a keyboard. Overlaid text reads, “The Top 10 Key Performance Indicators for Email Marketing.”

… Determining the success of your email marketing campaigns!

Why You Should Care About KPIs

There’s no beating around the bush. You want your marketing campaigns to succeed. You want to be part of the majority — the whopping 60% — of businesses seeing a massive ROI boost thanks to email marketing. In order to do this, you’ll need a good email service provider and some brain fuel, because your success is measured through key performance indicators — also known as KPIs.

The Basics: How to Start Tracking Email Marketing Metrics

Before I start to really dig into today’s post, I want to ask you a question. Do you have a good, reliable email service provider (ESP) lined up? There are umpteen different email service providers on the market right now, but not all of them are worth the price. Some are better than others, and taking the time to find the perfect one for your needs is worth the extra effort.

[And here I shall insert my shameless endorsement for Klaviyo because I will die on the hill that the ROI you'll see will eclipse whatever extra money you spend for this ESP]

A black-and-white photo of a line graph. Overlaid text reads, “The Basics: How to Start Tracking Email Marketing Metrics.”

Once you have your ESP lined up, it’s time to get going!

Somewhere within your email client is a campaign performance dashboard. Depending on which email service provider you’re using, you’ll likely be taken to a list of your email campaigns. Click on one — it doesn’t matter which! — and take a peek at it.

What do you see?

An edited photo of a sample Klaviyo metrics page.

The answer should be something like “a whole lot of data”!

(For your convenience, I’ve included a handy example of a campaign performance page in Klaviyo. Your metrics will not be the same, and the layout of the webpage depends upon which email service provider you’re using.)

If you want to optimize your existing leads and plan for future growth, then this is your playbook. Your email metrics are essential tools, and running successful email marketing campaigns depends upon your ability to understand and act upon what the numbers tell you.

What Is a Key Performance Indicator?

Here, you’ll be looking for key metrics. Some people may call these email marketing KPIs, but it all means the same thing. Out of all of our email analytics, these are the most important metrics.

A round chart listing the top ten email KPIs. See the list below for the text.

Without further ado, here are the ten KPIs that you should pay attention to as you develop your email marketing campaigns:

  1. Bounce rates
  2. Click-through rate (CTR)
  3. Click-to-open rates
  4. Conversion rates
  5. Email forwarding and sharing rates
  6. List growth rate
  7. Open rate
  8. Return on investment (ROI)
  9. Spam complaints
  10. Unsubscribe rates

Keeping track of these key metrics will help you improve your future marketing efforts. However, before I continue, I want to emphasize that you should still pay attention to other metrics. All of your data is useful to some degree, and failing to heed its advice will impact the relevance and effectiveness of your content.

Now, having said that, let’s take a look at what all of this valuable data means!

Up Close and Personal With Bounce Rates

To make things simple, I’ll be following the order of the list above. That means our first order of business is the humble bounce rate.

A black-and-white photo of UCLA. Overlaid text reads, “Up Close & Personal With Bounce Rates.”

Also known as the “Emails Delivered” metric, your bounce rate tells you how many subscribers are actually getting your email marketing. Think of it as a way to determine the number of emails delivered for each campaign.

How to Determine Your Bounce Rate

Most email service providers automatically calculate your bounce rate, but it’s still nice to know the math behind the magic. Your bounce rate is the total number of emails that have bounced divided by the number of emails sent. Multiply the result by 100 to get your percentage.

A shareable image with a colorized photo of downtown Los Angeles. There is overlaid text. The heading says, “How to Find Your Bounce Rate.” Beneath this is the bod text: “Your bounce rate is the number of emails that get delivered. It can also be called the ‘inbox placement’ rate. You want lower bounce rates, and you can determine your bounce rate with the following formula: (Bounced Emails ÷ Sent Emails) × 100.”

You may want to refine this formula even further, as there are a few different types of bounces.

Hard Bounces

Hard bounces happen when an email is not delivered at all. The most common reason for a hard bounce is an invalid email address. Usually, these messages are being “delivered” to a non-existent email address, and — because the email client is incorrect — the email fails to reach a valid destination.

There are ways to mitigate these bounces, including hard-coded checks — known as a double opt-in — for invalid email addresses, but you’ll never avoid them all. Keep an eye out on these, because your internet service provider will assign your brand a reputation based on your hard bounces. If you notice any, remove the problematic address immediately.

Soft Bounces

Unlike hard bounces, soft bounces will not negatively impact your reputation. A soft bounce occurs when a valid email address is temporarily unavailable. Usually, this is because the recipient’s inbox is full or their internet service provider is having technical difficulties. Feel free to re-send any soft bounces; they will likely be delivered once problems with the email client are resolved.

Bounce Rates, Sender Performance Scores, and You

Before I move to the next topic, I want to briefly bring up the topic of sender performance scores. These ratings range from 1–100, and they are assigned by both email service providers and internet service providers. In general, they are based on a brand’s overall inbox placement rate, which means that you should always be checking and minimizing your hard bounces.

When a brand has a higher reputation score, its messages are considered more trustworthy. In other words, a brand with a score of 96 will reach more email clients than a competitor with a score of 82.

A colorized photo of a man doing a flip. There is overlaid text. The header reads, “Performance Scores, Bounced Emails, and You.” Beneath this is smaller text: “Your bounce rate directly impacts your sender performance score. If your score is low, then you’ll have a hard time reaching your target audience.” The second paragraph reads, “To improve your sender performance score, keep your bounce rate low. The ideal sender reputation score is 80 or more. Anything below 70 is problematic.”

For the best results, you’ll want to keep your sender performance score above 70. Anything beneath this threshold is generally filtered as spam by most email clients.

Consulting Your Click-Through Rates

Time for the next topic, and it's one you probably are already well aware of:

A black-and-white photo of a messy office desk with overlaid text: “Consulting Your Click-Through Rates.”

Your click-through rate (CTR) is another key metric, and its job is to determine how well your call-to-action worked. The CTR is a measurement of how many people opened your email message and clicked on your call-to-action. Commonly abbreviated as CTR, this essential email marketing metric is a valuable insight into your subscriber list.

How to Determine Your Click-Through Rate

To find your overall CTR, you’ll follow a simple formula. First, divide the number of clicks by the total number of emails sent. Multiplying the resultant figure by 100 will yield your click-through rate, which is directly proportional to how many quality subscribers your brand has.

A colorized photo of a computer mouse. There is overlaid text. The heading says, “Consulting Your Click-Through Rates.” Beneath this is text: “To measure the effectiveness of a campaign, marketers will evaluate its click-through rate. To determine what your CTR us, use the following formula: (Total Clicks ÷ Emails Sent) × 100.”

In some cases, the click-through rate will overlap with your conversion rates — which we’ll be looking at momentarily — but this isn’t always true. That's because clicking is a type of conversion.

Of course, the conversion most businesses care more about is whether that click results in a purchase, and we'll be discussing conversion rates in few sections. But with both statistics, you can set up an irresistible automation that goes out to users who clicked but didn't purchase.

How Are Click-Through Rates Used?

One of the biggest benefits of tracking your click-through rate is the ability to determine whether or not you’re delivering consistent, relevant content to your subscriber list. As great as it is to see a high open rate, those views aren’t worth much if people don’t follow through and enter the sales funnel.

When combined with a bit of A/B testing, your click-through rate becomes an essential part of your email marketing arsenal. In fact, many of your campaign goals will revolve around your click-through rate.

Checking out Your Click-to-Open Rate

The click-to-open rate is a bit of a multifaceted metric. As you might have guessed from its name, it’s closely related to your CTR, but it is not the same thing!

A black-and-white photo of a messy desk with overlaid text: “Checking Out Your Click-to-Open Rate.”

The CTOR metric measures how the percentage of unique users who received the email, opened the email, and clicked on a link within the email message. Not just the CTA, but any link at all. It’s a very, very fine line, but these differences are essential to understanding your email analytics.

How to Determine Your Click-to-Open Rate

Time to bust out your calculators again! Your email client will likely provide you with your CTOR metrics, but it doesn’t hurt to double-check that information. At the very least, being able to calculate the CTOR on the go is a neat breakroom trick. (Maybe… it may just make you look like a bit of a dork!)

A colorized photo of an office with overlaid text. The heading reads, “How to Find Your Click-to-Open Rate.” Beneath is smaller text: “While similar to your click-through and open rates, your CTOR is a separate metric. To find your CTOR, use the following formula: (Unique Clicks ÷ Unique Opens) × 100.”

A campaign’s CTOR is determined by dividing the number of unique clicks by the number of unique opens. This gives you the percentage, which can be multiplied by 100 to get a whole number.

Is CTOR Better Than CTR?

When you’re examining your call-to-action metrics, you may hear that one is better than the other. There are claims floating around that the “CTR is dead,” and they have as much weight as the egregious assumption that “email marketing is dead.

Never disregard any of your customer data! It’s all important, and each measurement has its place. When you step back and take in the totality of your email marketing metrics, you will need to have both your CTOR and CTR.

Yes, they overlap, and that’s the point! You’re looking for discrepancies between the two, and that information is what informs your email marketing team.

Changing Things Up With Conversion Rates

At the end of the call-to-action metric rainbow is the ultimate goal of every email marketing campaign: a conversion.

A black-and-white photo of an office desk with overlaid text: “Changing Things Up With Conversion Rates.”

Your conversion rate measures how many people followed your call-to-action to the end. This usually means that a customer bought a product, but every email marketing campaign is different. Completed surveys, re-engaging customers, and updated email preferences are all examples of non-monetary conversions.

How to Determine Your Conversion Rate

The pattern is in place, and you know what’s up next!

A colorized photo of downtown Los Angeles. The overlaid heading reads, “How to Find Your Conversion Rate.” Beneath this is smaller text: “Knowing your conversion rate is essential if you’re planning on running any email marketing campaigns! To determine what yours is, use this formula: (Actions Complete ÷ Total Emails Sent) × 100.”

If you’re willing to do a bit of math, you can double-check your email service provider. First, divide the number of subscribers who completed the desired action by the total number of emails sent. Multiplying this by 100 will yield your conversion rate.

Tips for Improving Your Conversion Rate

As a disclaimer, I definitely don’t have enough time to properly lay out the framework for boosting your conversions in this post. In fact, conversion rate workshopping may as well be its own post! What I can do, however, is tell you what I tell everyone who asks for advice…

If your email marketing metrics are consistently failing to meet your campaign goals, then it’s time to start looking for a dedicated email marketing agency. As convenient as full-service agencies may be, there’s something special about dedicated digital firms. The staff of these firms, such as The Email Marketers, is dedicated to email marketing. They know how to read the metrics, and they’re experts at delivering results.

Expanding Your Reach With Email Sharing and Forwarding Rates

After all of those complex metrics, it’s time to take a break with something that’s upfront and simple!

A black-and-white photo of downtown Los Angeles. Overlaid text reads, “Expanding Your Reach With Email Sharing and Forwarding Rates.”

Your email sharing and forwarding rate show how many people have sent your email campaign to their friends and family. Now, when you’re just starting, don’t feel too discouraged if this is a fairly low stat. It takes time and testing to nail down the best way to keep customers engaged, and many email recipients may not be open to spreading your email marketing messages.

However, if you manage to boost your overall sharing rate, you might just surprise yourself by netting a few new subscribers. Though sharing is not one of the most pressing email marketing KPIs, it’s still worth keeping an eye on the numbers.

Taking Advantage of Shares

If you want to really amplify your marketing efforts, then it may be worth looking into incentivizing shares. Some brands offer bonuses — often in the form of discounts — to subscribers who forward or share an email.

An example email from Treehouse. The message encourages email recipients to share it, complete with a CTA: “Tell your friends!”

Some email marketers even create campaigns that are specifically geared towards sharing. In the above example, we have a lovely and simple campaign from Treehouse. Pay particular attention to the email subject line, which clearly and succinctly encourages users to pass the message along!

Nurturing Your List Growth Rate

If your campaign goal is reaching new subscribers, then your key metric will be your list growth rate.

The list growth rate gauges how many people are being added to your subscriber list. It’s an important metric, but it shouldn’t be something that severely stresses you out. Shrinkage happens, and people will unsubscribe. Nonetheless, you still want this number to be fairly high.

How to Determine Your List Growth Rate

Now, the list growth rate is one of those things that it might be better to leave for your email client to calculate. However, for the curious, there is a formula. It’s just a bit more complex than some of the others.

A colorized photo of downtown Los Angeles. Overlaid text reads: “How to Find Your List Growth Rate.” Beneath this is the body text: “Compared to other email metrics, the formula to determine your list growth rate is fairly complex. It looks like this: (New Subscribers - Unsubscribes - Hard Bounces) ÷ Subscribe List Size.”

To calculate your list growth rate, you’ll need a few different metrics. The first step is to subtract your unsubscribes and hard bounces from your new subscribers. Once you have that result, divide it by your total number of subscribers.

Investigating Your Open Rate

The open rate is another straightforward email marketing metric, but it has a few caveats. It is closely related to the CTOR and CTR, though its functionality is a bit more limited.

A colorized photo of downtown Los Angeles with overlaid text: “Investigating Your Open Rate.”

The open rate is a simple measurement of how many people opened your delivered emails.

Things to Know About Open Rates

As far as email marketing KPIs go, this is one of the oldest measurements of success, and that comes with a few pitfalls. One of its biggest foibles is that Apple Mail users will not have accurate open rate stats. As of the iOS 15 update, the platform vastly overestimates the actual open rate. Other inbox providers have their own rules for counting opens, so keep that in mind, too.

That’s not to say it’s an entirely useless email marketing metric, though! When paired with open rate by device stats, the open rate is a fairly decent measurement of subject line efficacy. Open rates may not be one of the premier email marketing KPIs, but it has its uses.

Calculating Your Return on Investment

For every email marketer, there’s only one metric more important than the conversion rate: the ROI. This is the number that determines the efficacy of every email marketing campaign. It is one of the essential email marketing KPIs, and it usually determines what next year’s email marketing will look like.

A colorized image of Los Angeles with overlaid text: “Calculating Your Return on Investment.”

Tracking your ROI can help you maximize your revenue per subscriber, and combining that information with other marketing metrics can help you avoid landing in a junk folder in the future.

How to Determine Your ROI

For one the king of all email marketing KPIs, calculating the ROI is fairly simple.

A colorized photo of Los Angeles. The heading says, “How to Find Your Return on Investment.” Beneath this is text: “Finding your ROI is a fairly simple formula, and it looks like this: (Money Gained - Total Budget) ÷ Total Money Spent × 100.

To calculate the ROI, subtract the amount of money gained from your email marketing campaign from the total spent. Divide the result by the campaign budget, then multiply that number by 100.

Facing Fearsome Spam Complaints

From one of the best email marketing metrics to the worst, I bring you the spam complaint rate. This is one of those metrics that you want to be a nice, round zero! You never want to end up accruing spam complaints, and you want your delivered emails to be received warmly.

A black-and-white photo of Los Angeles, California with overlaid text: “Facing Fearsome Spam Complaints.”

The higher this number is, the more likely you are to suffer in the deliverability department. This ultimately causes a rolling snowball, which will impact your revenue per subscriber when it finally bursts.

How to Avoid Spam Complaints

To avoid becoming spam, you’ll want to pay special attention to your subject lines. Make sure that everything about your email campaigns is on the up and up. Paradoxically, you’ll also want to include a clear and obvious unsubscribe link, and the process to leave your list should be simple.

Remember that the number of emails delivered will ultimately influence the efficacy of every email campaign. The more emails you send, the more likely you are to end up in a junk folder. Even interested customers may accidentally report your messages as spam, so be sure to include disclaimers on your contact form.

The Surprisingly Important Unsubscribe Rate

Last — but certainly not least — on our massive list of email metrics is the unsubscribe rate.

A photo of downtown Los Angeles, home to The Email Marketers. Overlaid text reads, “The Surprisingly Important Unsubscribe Rate.”

Now, this number may sound bad. After all, fewer people means a smaller audience, and a smaller audience means fewer emails delivered. However, I’m here to drop some surprising news: sometimes, you want people to unsubscribe!

Yes, it sucks to see all of your hard work being ignored, but a large number of unengaged customers impacts your email marketing metrics. At the end of the year, when all of the data is aggregated, you’ll be facing lower performance than you anticipated, and that will hurt your overall revenue per subscriber.

How to Determine Your Unsubscribe Rate

The unsubscribe rate just might be one of the simplest formulas on this list!

A photo of Los Angeles. Overlaid text reads, “How to Find Your Unsubscribe Rate.” Beneath this is text: “The subject line of the unsubscribe rate is simplicity. The formula is super easy: Unsubscribers ÷ Number of Emails Sent × 100.”

All you need to do is divide the number of people who have unsubscribed from your email list by the number of emails sent.

When to Take Advantage of Unsubscribes in Your Email Marketing Campaigns

If your conversion rate and email marketing metrics have been dropping, then one of the weak spots you’ll want to investigate is the number of emails delivered to unengaged subscribers. These messages are ultimately missing their target audience, and that’s hurting your bottom line.

This is when you should deploy the email marketer’s secret weapon: the unsubscribe campaign.

How to Improve Your Next Email Marketing Campaign


That was a lot of information, right? Fortunately, we’re all done! Class is almost dismissed, and I’m winding down the lecture. However, before I go, I want to remind you of the amazing power of email marketing. With the right insight and plenty of email marketing KPIs, anyone can learn to be an expert email marketer.

Not everyone has the time for that, though, and that’s okay! There are plenty of amazing agencies out there. If you’ve been struggling with your email marketing efforts, then it might be time to invest in some professional help. Don’t be afraid to give me a shout! I’m always willing to help people out, and I love seeing businesses succeed.

From improving subject lines to lowering your unsubscribe rate, email marketing is all about boosting the impact of your business. If you’re ready to boost the revenue per subscriber and skyrocket your marketing investment, then it’s time to get in touch with an expert.