There are over 4 billion email users worldwide, and that number’s still growing. Many of these users have inboxes chock-full of marketing emails — often hidden away in a “promotions” folder.

Crafting the perfect emails to successfully stand out from competitors, connect with readers, and generate leads is anything but easy.

The best way to measure and optimize your email marketing efforts is to use key performance indicators (KPIs). These essential metrics help marketing teams monitor crucial factors that make or break a campaign.

To help you understand and choose the right email marketing KPIs, we’ve explained what they are and listed the 15 most crucial ones for every campaign.

Understanding Email Marketing KPIs

Email marketing is the process of sending emails to customers and leads to promote your brand or product.

Your email marketing campaign can include promotional emails, offers, abandoned cart emails, “back in stock” emails, a content round-up, newsletters, company updates, and more. Check out examples of different email types for inspiration.

Marketers use audience segmentation and create multiple variations of the same email to resonate with smaller groups within their target audience.

In 2022, most brands take advantage of email marketing. Here’s why:

  • Email marketing has the highest return on investment (ROI) among popular marketing channels, averaging a return of $36 for every dollar spent.
  • A majority (87%) of B2B marketers say email is among the top free organic channels for distribution.
  • 31% of marketers said that email newsletters were the best performing content type for lead nurturing.

What is a KPI, and why is it important?

A Key Performance Indicator (KPI) is a measurable metric that indicates the progress of your marketing campaign toward its goal(s). The most common marketing KPIs are related to lead generation, conversions, revenue, and engagement.

KPIs guide your marketing campaigns. When the metrics are good, your campaign has a higher chance of success. But, poor performance metrics call for immediate changes to move your campaigns in the right direction.

Without KPIs and goals, your marketing campaign is aimless and could end up costing more money and time than it recovers.

Setting email marketing KPIs

Every email marketing campaign has multiple goals and KPIs to measure performance. Your goal could be to generate X number of leads, gain X new email subscribers, improve open rates to X%, etc.

Marketers use different ideologies to set email campaign goals. The most popular goal-setting methods are SMART (Specific, Measurable, Achievable, Realistic, and Timely) and CLEAR (Collaborative, Limited, Emotional, Appreciable, and Refinable).

You can use these methodologies to set relevant goals for your email marketing campaigns and then decide the correct KPIs to track.

15 Essential Email Marketing KPIs to Track

KPIs are the bread and butter of successful email marketing. Without them, your email marketing campaigns have no direction — you have no way to tell if they’re working or not.

Here are 15 KPIs that every email marketer must track:

15 crucial email marketing KPIs

1. Delivery Rate

The delivery rate is a basic KPI that tells you the percentage of emails that are reaching your subscribers’ inboxes. Your email marketing campaign won’t do anything if subscribers aren’t even receiving your emails.

If you send 50 emails and only 20 reach an actual person’s inbox, your campaign is wildly ineffective.

To calculate the delivery rate, use this formula:

Deliverability rate = Number of emails delivered ÷ Emails sent X 100 

While 100% deliverability rates are impossible to achieve, you should aim for at least 97% deliverability.

Low delivery rates could be caused by:

  • No custom authentication
  • Using single opt-in sign-up forms
  • Making it hard for users to unsubscribe
  • Utilizing “spammy” subject lines and body copy
  • ISP issues

Another related metric to track is the Inbox Placement Rate (IPR), which shows the percentage of your emails reaching the user’s inbox rather than being sent to the spam/junk folder.

2. Open Rate

Open rate is the percentage of emails that your readers actually open. It indicates the interest your audience has in what you’re sending them. A high number of subscribers with a poor open rate means it’s time to change up the content of your emails.

To calculate the open rate, use this formula:

Open rate = Number of emails opened sent ÷ Emails sent X 100 

Fortunately, most email marketing solutions will show this metric without any calculation needed.

The average open rate across all industries was 28.80% as of January 2022. Faith-based organizations had the best rate (40.66%), followed by Child Care Services (37.61%) and Family and Social Services (35.51%).

Table of average open rates

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You can improve your open rate by sending personalized content, optimizing subject lines, and crafting compelling body copy.

Marketers use open rate as a comparative metric, meaning they compare the open rate from week to week, month to month, and email to email.

3. Click-Through Rate (CTR)

The click-through rate shows the percentage of users that clicked on a link within an email. It’s a crucial email metric to track since it directly shows you how many subscribers are actively engaging with your content.

You can calculate the CTR of your emails using this formula:

Total or unique clicks ÷ Number of delivered emails X 100

You can use both the total number of clicks or the number of unique clicks to calculate the CTR for the campaign, but you must use the same factor throughout the entire campaign.

Remember to focus only on delivered emails while calculating click-through rates.

The CTR is also used extensively during A/B testing to understand which email design and link copy get the most clicks.

4. Bounce Rate

Bounce rate is the percentage of emails that were not delivered to the people in your email list. The average bounce rate is 10.14%.

Of the measured industries, the Legal Services industry has the highest estimated bounce rate at 17.15%. On the other hand, emails sent by Independent Artists, Writers, and Performers had the lowest bounce rate (3.27%).

You can calculate this by using:

Bounce rate = Number of bounced emails ÷ Number of emails sent x 100

There are two types of bounce rates for you to track: hard and soft.

A soft bounce is caused by a temporary error like a server error or problems with the recipient’s inbox. In cases like this, the server holds the emails and delivers the emails once the issue is resolved.

A hard bounce is caused by an invalid, fake, or closed email address. While some of your recipients might have changed their emails, a higher hard bounce rate also indicates that users are providing fake emails on your sign-up forms. A double opt-in form can help reduce this issue.

With single opt-in, a user fills out a form and is subscribed to your email campaigns immediately. But a double opt-in sends them a link to confirm their email addresses first. That ensures they’ve provided the right one before you send a single email or the lead magnet.

Removing addresses that are hard bounces is crucial since your ISP or email marketing provider uses it to measure the sender’s reputation. ISPs view high bounce rates as a sign of spam.

5. Total vs. Unique Open Rate

Marketers need to go deeper than measuring the basic open rate. They must differentiate between the total open rate and the unique open rate.

The total open rate measures how many times your email was opened. So, even if one user opens your mail multiple times, it’s counted as an “open” and included in this metric.

The unique open rate counts only the first time a subscriber opens your email. All subsequent opens from that user are ignored.

This is a crucial distinction. If a user opens your email messages multiple times or a bot opens them thousands of times, it can impact the total open rate and create an illusion of a successful campaign.

The unique open rate should be the focus of marketers aiming to grow their email lists.

6. Sharing Rate

The best sign of your readers being engaged with your content is them sharing it with their friends, peers, and family. A high sharing rate is a major contributing factor to a successful email campaign.

Subscribers that forward your emails act as brand ambassadors. They provide honest reviews to their acquaintances, which serves as social proof and boosts your brand’s credibility.

You can calculate the sharing rate using:

Email sharing rate = Number of clicks of the share or forward button ÷ Number of delivered emails x 100

Marketers should strive for high forwarding rates. Shared emails create new lead generation opportunities and drive sales.

7. Unsubscribe Rate

How do you know your content or sending schedule is working or not? The unsubscribe rate. A high unsubscribe rate is a cause for concern and change, while a low unsubscribe rate indicates your campaign is working.

The unsubscribe rate is the percentage of people on your email list who opt to unsubscribe after opening.

Increased unsubscribe rates could be caused by:

  • No audience segmentation
  • Sending too many emails
  • Poor content or email design

Audience segmentation is key to creating personalized content that resonates with readers and generates interest in your brand or products.

It’s also a good idea to lead users to a landing page that asks them why they chose to unsubscribe. This feedback allows you to improve.

8. Spam Rate

Spam rate is the number of emails marked as spam by receivers. So, if you have sent 100 emails and one is marked as spam, then your spam rate is 0.1%.

Users can report an email as spam using the button in their inbox. If they click the unsubscribe button and it doesn’t work, users are likely to just block and mark it as spam instead.

Spam button in a Gmail email

ActiveCampaign estimates that the acceptable spam rate is less than 0.1%. If your spam rate is higher than this, it could lead to deliverability issues.

To keep your spam rate low:

  • Only send emails to users who have actually opted-in to your list.
  • Use double opt-in.
  • Make it easy to unsubscribe.
  • Avoid paid email lists from third parties.
  • Send welcome emails to contacts that have signed up.

If your emails are regularly marked as spam, email service providers will automatically deliver them to your junk folder. It could take months to repair this.

9. Conversion Rate

The conversion rate is the percentage of users that clicked on links within your email and then completed a purchase, enlisted your services, or performed another desired action.

For example, if you sent an email with a discount to sign up for a course you’re offering, then anyone who signs up is counted as a conversion.

The conversation rate is a vital metric since it directly shows how successful your campaign is at generating leads and sales.

You can calculate the conversion rate using:

Conversion rate = Number of users who took the desired action ÷ Number of total emails delivered x 100

Since conversions are the primary goal of most marketing campaigns, this is a vital metric to track. It’s also a measure of engagement.

For example, if the open rate is high but the conversion rate is low, you need to look at the gaps in your campaign to see where in the buyer journey users are turned off.

Successfully tracking your conversion rate requires integration between your email platform and your analytics tools. The most common way to do this is to use custom URLs.

10. List Growth Rate

The list growth rate shows whether your email subscriber list is growing or shrinking. It’s the simplest way to determine if your campaign is effective or not.

A growing list indicates that your readers like what you send them and are engaged. A stagnant email list shows that your strategy needs to be optimized. In a worst-case scenario, your email list could be shrinking instead of growing and calls for a significant change to your strategy.

You can calculate list growth rate using:

List growth rate = [(Number of new subscribers) – (Number of unsubscribers + spam complaints)] ÷ Total number of email addresses on your list] x 100

One way to ensure a steady organic list growth rate is to create shareable content that your subscribers will forward to peers. Wider audience appreciation will automatically boost your email list.

If you want to supercharge your list growth rate, an SEO campaign focused on generating leads is a great idea. If you need help with the strategy, planning, or content creation for such a campaign, HOTH X can help.

11. Engagement over time

Track engagement levels over a period to identify unengaged recipients. These users would have opted in to receive your emails, which means it gets delivered to their inbox, but they don’t open it.

Unengaged readers pad your list numbers but cost you money and can affect where your emails end up. It’s advised to remove these subscribers from your email list.

In some cases, email providers might see a high number of unopened emails from your address and send anything new directly to a users’ junk or spam folder.

Some marketers call emails that users opted in for but no longer want to read as “graymail.” They strongly advise purging your email list regularly and claim that it delivers much better performance in the long term.

12. Mobile Open Rate

Around 60% of users open their email on their phones or tablets in January 2022, but many companies still fail to optimize for mobile devices.

Your readers will be frustrated if they open an email and the layout is misaligned or the text is unreadable. Consequently, this leads to more unsubscriptions and lower open rates.

Dive deeper into your open rates to segregate opens by device. You can do this by using email marketing software. Then, use this formula to calculate the mobile open rate.

Mobile open rate = Number of opens on mobile ÷ All opens x 100

If a significant amount of your users are reading your emails on mobile, you must optimize both the emails and the pages they link to for all major mobile devices.

13. Revenue Per Subscriber

Determining the revenue per subscriber is key to improved audience segmentation. When you know which type of email group within the target audience is most likely to make a purchase, you can develop emails to further encourage buying.

The revenue per subscriber also shows the worth of your email list. An extensive list that’s not generating much revenue consumes time, money, and resources that could’ve been spent on other lead generation and nurturing efforts.

You can calculate the revenue per subscriber using:

Revenue per subscriber = Total revenue generated ÷ Number of subscribers

Marketers can use this metric to see which lists and campaigns drive the highest return on investment.

14. Revenue Per Email

The revenue per email shows you which type of email is the most effective. For example, if promotional emails generate more income than content round-ups, you know which type to focus on.

You can calculate this by using:

Revenue per email = Revenue from each email ÷ Number of delivered emails

This metric also helps you measure the real marketing impact of every email you send — the dollars it adds to your bottom line.

15. Overall ROI

The overall return on investment (ROI) shows the profitability of all your campaigns. It’s used to track the effectiveness of your email marketing campaign and is often the metric that most corporate higher-ups care about.

ROI is the amount you generated for every dollar spent.

You can measure the ROI by using this formula:

Email ROI = (Revenue gained – Amount invested in the campaign) ÷ Amount invested in the campaign x 100

It’s worth noting that while executives might focus on overall ROI, marketers should rely more on the goals of a specific campaign or email. For example, ROI is not the best metric to track for an email campaign designed to build brand awareness.

Tips to Boost Your Email Marketing Performance

If you’re tracking the above metrics and the results are not as great as expected, then it’s time to revamp your email marketing campaign. Here are some tips you can use:

Improve your email marketing campaigns

1. Create Targeted Emails

First things first, if your lists and campaigns are not segmented, they need to be. Email segmentation is the practice of dividing your subscriber lists into smaller groups and creating variations of emails to appeal to each group.

SuperOffice conducted a test where they sent an email to their main subscriber list vs. a segmented list, and the latter showed a staggering 94% open rate.

SuperOffice noted increased open rates after audience segmentation

(Image source)

Audience segmentation is widely used as part of digital content strategies but is even more effective for email marketing. When your readers feel like you’re catering to their interests rather than bombarding them with generic emails, they’re more likely to open and read through your emails. Personalization can also boost your CTR.

2. Get the Basics Right

Create a checklist of all the primary elements within your email and make sure they’re always up to snuff. These include:

  • A relevant and clear subject line
  • Powerful visuals
  • Compelling body copy
  • Well-placed CTA buttons (or links)

The subject line is crucial in deciding if a user opens your mail or not. Many factors within the subject line play a role. A report from GetResponse showed that subject lines with the phrase “newsletter” in them had the highest open rate (24.77%), followed by “video” (19.65%) and “!” (19.47%).

subject line phrases with the highest open rates

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While stats like this are a starting point, remember that you’re creating content for your audience, and general statistics may not apply to your niche or industry.

Your emails should look appealing, have personalized content, and make it easy for users to take action.

3. Use Different Email Types

Diversify your email content calendar with different email types. Don’t just rely on one type of email.

If you’re sending 3 to 5 emails per week, then create a mix of promotional emails (discounts, limited-time offers) and informative ones (content round-up, update newsletter).

And don’t disregard transactional emails (back in stock, abandoned cart, etc.); they can be powerful marketing tools as well.

You can also use surveys and feedback forms to regularly gather subscribers’ opinions on your products or services.

4. Test Emails

A/B test your emails to see how different elements impact open rates, CTR, and audience engagement.

Try out different layouts, multiple subject lines, change up the body copy, and use varying color schemes to see which works best.

Also, test your emails on all major devices (both desktop and mobile) to ensure nothing is out of place.

5. Leverage Email Marketing Automation

You can use email marketing automation software to streamline your entire campaign. From email creation to distribution, software can help you speed up the process.

For example, many advanced email marketing tools let you send timed emails or emails triggered by user actions. So, rather than manually sending an abandoned cart email (which would be impossible to do at scale) you can automatically send them when users don’t complete a purchase.

Multiple email types can be automated, including welcome emails, birthday emails, seasonal emails, blog updates, and more.

When a large part of your email marketing campaign is automated, you can focus on crafting high-value personalized emails that are fine-tuned to your subscribers.


When done right, email marketing can be a powerful asset for all your marketing campaigns. All these metrics and elements might seem challenging to understand for a newbie, so a good idea is to focus on a few email marketing KPIs to start with.

After you’ve improved your open rates with better subject lines and segmentation, you can start working on driving more revenue per email, for example.

If your biggest issue is that you have a limited number of subscribers, focusing on SEO to build your email list could be a better idea — and HOTH X can help!