When compared to other communication channels, email has a gargantuan advantage – it’s fully trackable in every aspect.

As email marketers, you are perfectly aware of email marketing metrics like open, click-through and unsubscribe rates. But, are these email marketing KPIs enough when it comes to determining the success of your email campaign? 

“That which is measured improves.” – Karl Pearson-Cater

There’s a lot to talk about when it comes to email marketing. We can spend days (weeks even) discussing how to optimise your emails, common email design mistakes, email design best practices, email deliverability,  email engagement and more. But, when all is said and done, it doesn’t matter how perfectly optimised your emails are or that you’ve implemented all known best practices if you can’t see and measure your email marketing efforts. After all, the best email marketing decisions are data-driven. So, in order to establish the success of your email campaign, there are certain email marketing KPIs you simply cannot do without and which can help you increase your email marketing revenue. 

In this article, we’ll cover the following email marketing KPIs:

  1. Open and conversion rates
  2. Click-through and click-to-open rates
  3. Bounce, unsubscribe and complaint rates
  4. Delivery and deliverability rates
  5. Email campaign ROI

Ready to dig in?

In order to be a masterful email marketer, there’s one very important thing to keep in mind – it takes time. You might have learnt everything you think there is to know about email marketing. But, if you haven’t determined your business’s goals and considered all possible email marketing KPIs, knowing about common email marketing rookie mistakes and optimising emails won’t lead you to success.

As email marketers, you create email campaigns for different purposes each with a different goal in mind. Therefore, there are certain email marketing metrics you should be familiar with to measure the success of your email marketing efforts.

The key email marketing KPIs can be divided into two categories – 

a) on-mail KPIs – these metrics refer to the recipient’s interaction with your email campaign and they’re tracked directly by you ESP making them automatically available and easy to read;

b) off-mail KPIs – these metrics measure everything that originates from the email but is then directed elsewhere (a website, a blog, an e-commerce site, etc.) These KPIs analyse numerous aspects related to the email channel like the volume of attracted traffic, average purchase amounts and so forth. Your ESP is not the one providing these metrics. They come from third-party analytic systems such as Google Analytics, for example.

Today, we’ll focus on the on-mail KPIs every email marketer should know about, follow and analyse.

Email Marketing KPIs You Should Pay Attention To

Open Rate (OR)

An open rate indicates how many times your subscribers opened your email compared to the total number of emails delivered (or sent). Most ESPs automatically calculate this email marketing KPI for you. However, if you want to double-check the numbers, you can always use this formula – 

Email Open Rate = (Number of Emails Opened / Number of Emails Delivered) x 100
Example: 12,150 opened emails / 37,000 emails delivered x 100 = 32.8%

Email service providers track email opens by embedding a small transparent image or a tracking pixel (a.k.a 1×1 pixel) into your marketing emails which are recalled whenever a recipient gets your email.

Recipients can open your email multiple times which consequently will be counted by your ESP increasing the open rate. However, if they don’t download the image, the open rate cannot be tracked. 

The elements of your email which affect the open rate the most are the subject line and the preheader. Therefore, make sure you A/B test your email campaigns before sending them to the recipients. 

What’s a good open rate? Well, that’s a big question. Across the board, open rates for email marketing campaigns hover around 25%. Though, if you manage to get a higher rate than that then you’re certainly doing something right.

Keep in mind that getting an accurate open rate can be tricky. Some people might only open the text version of your email (which won’t register as an open) and some email clients block images by default (with Outlook, for example, you have to manually download the images). On the other hand, some recipients might use preview panes for their email (Outlook is again an example here). In this scenario, an email open is counted but the recipient may not have read the email at all.

Conversion rate

This email marketing KPI is the one that matters the most. However, don’t start seeing pound signs yet.

A conversion rate indicates the number of recipients that have acted on your email. It represents the percentage of recipients that have clicked on a link within your marketing email and then completed an action – filling a signup form, participating in a sale or claiming a discount designed specifically for them.

The formula you can use to calculate your conversion rate is – 

Conversion Rate = (Number of Completed Actions/Number of Email Delivered) x 100
Example: 400 completed actions / 8,000 emails delivered x 100 = 5%

Conversion rates are essential for determining your ROI. By knowing how much you’ve spent on an email and the number of subscribers converted, you can pretty easily determine if the funds, as well as time you’ve put into your email marketing campaign, are paying off.

What is a good conversion rate? That’s a tough one to answer. It all depends on your business’s goals for each of your campaigns as well as the industry sector. You can find more details about the average conversion rate for a range of sectors (including B2B conversions) here.

The best way to successfully measure this very important email marketing KPI is by integrating your ESP as well as your web analytics (like Google Analytics) and by creating a unique tracking URL for each link in your marketing emails.

It’s important to keep in mind that your CTAs are directly linked to your conversions. As such, they must be linked directly to the end-goal of your email campaigns.

Click-through rate (CTR)

A click-through rate (CTR) is another common email marketing KPI which helps businesses to establish the level of success of their email marketing campaigns.

A CTR measures the number of recipients who clicked on one or more links within a given email. The following formula can help you calculate your CTR – 

CTR = (Number of Total Email Clicks/Number of Delivered Emails) x 100
Example: 1,500 email clicks / 25,000 emails delivered x 100 = 6%

As an email marketer, you should also measure individual and holistic CTR. Individual CTR measures how many people clicked through, while holistic CTR tells you how many clicks took place.

You must be vigilant when creating your email campaign if you want to increase your CTR. One option is to add links in strategically chosen locations throughout your email. Another is to carefully craft CTAs in order to draw the recipients’ attention. For example, what would be the colour of your CTA button, what about the text.

What’s a good CTR? As with your open rate, your CTR can be influenced by different things. Some businesses may observe a 20-30% CTR for welcome emails or email campaigns calling for specific actions (like downloading an ebook). However, an average click-through rate is around 4%.

In order to improve this crucially important email marketing KPI, you must carry frequent A/B testing – on wording, content layout, CTAs design as well as images used in your email.

Remember that clicking on the unsubscribe link might count as a click, too. However, that’s a ‘bad click’. So, be vigilant about tracking what recipients actually click on.

Click-to-open rate (CTOR)

A click-to-open rate (CTOR) indicates the number of clicks with respect to the number of emails opened. CTOR also measures how many recipients clicked on a link, however, it only takes into account recipients who got as far as opening your marketing email. 

This email marketing KPI does not include everyone on your mailing list or all the emails delivered. It is also the most accurate email marketing metric for measuring interactions. The following formula can help you calculate your CTOR – 

CTOR = (Number of Unique Clicks/Number of Unique Email Opens) x 100
Example: 800 unique clicks / 5,000 unique opens x 100 = 16%

A low CTR but a high CTOR could mean your emails are well crafted but you’re wasting a lot of effort sending emails to recipients who don’t want them. A low CTOR, on the other hand, suggests that your emails are falling flat once recipients open them.

What’s a good CTOR? Ideally, the answer to the question would be 100%. However, it’s highly unlikely to get such results. Unless, of course, you’re offering something the recipients wouldn’t want to miss from the get-go and they have no other choice but to take action. The average CTOR is around 20-30%.

It is important to keep in mind that some recipients can’t bear the thought of having unread emails in their inbox so they open everything. Yet, despite opening your email, they might not be in the mood for reading in or taking an action.

Overall, if you are wondering how many recipients close your emails immediately after opening them or the number of times they’ve interacted with the email’s content or visited your website, this email marketing KPI will give you the answer.

Bounce rate

As email marketers, we are all familiar with what a bounce rate is. However, let’s go through the details just one more time, shall we?

The bounce rate measures the number of recipients who did not receive your email. Basically, it’s the percentage of email addresses that returned an error after the email’s been sent. 

There can be a few reasons why an email bounced – 

a) the recipient has restriction filters;
b) the recipient’s inbox is full; or
c) the email address you’ve sent to is incorrect or mistyped.

There also two types of bounces – 

a) soft bounces – temporary issues with a valid email address. For example, a full inbox or problems with the recipient’s server; and
b) hard bounces – permanent issues with the emails on your mailing list. For example, invalid, closed or non-existent email addresses.

You can calculate your bounce rate using the following formula – 

Bounce Rate = (Total number of bounced emails/Total number of emails sent) x 100
Example: 80 bounced emails / 15,000 emails sent x 100 =  0.53%

Measuring your bounce rate might not be directly linked to your goals, yet it’s important to keep track of it in order to ensure the ‘health’ of your mailing lists as well as monitor any deliverability issues. A high bounce rate can result in a poor sender reputation and make your business look like a spammer in the eyes of the ISPs.

What’s a good bounce rate? Well, the answer should be quite obvious – as low as possible. However, it’s pretty much impossible to reach 0% bounce rate for a number of reasons – from changing between email service providers without updating SPF and DKIM records through ISPs having temporary issues to closed email addresses. 

Unsubscribe rate

This email marketing KPI is one of the ‘musts’ you should be tracking. There’s also much you can learn from it.

The unsubscribe rate represents the percentage of recipients who opted-out from receiving your future email messages. Basically, it counts the number of recipients who clicked on the unsubscribe link in your marketing email. Normally, most ESPs add this link to your emails automatically. However, if it’s missing make sure you add it as it’s also a legal requirement. You don’t want to force people to stay on your mailing list if they don’t want to be there, do you?

Your unsubscribe rate is usually automatically calculated by your ESP, however, this formula can help you do it yourself – 

Unsubscribe Rate = (Total number of people who unsubscribed/ Total number of emails delivered) x 100
Example: 25 people unsubscribed / 5,000 emails delivered x 100 = 0.5%

What’s a good unsubscribe rate? Depending on your emailing frequency, your unsubscribe rate will definitely fluctuate. A healthy unsubscribe rate is around 0.2%. Anything above this average should be alarming and will require your immediate attention. 

More often than not, a high unsubscribe rate can be quite discouraging. However, don’t let it get you down. Be positive. View it as a good thing. Why? Because it can help you fine-tune your subscriber lists and end up with people who want to get your emails. Ah, those recipients are also highly likely to interact with your marketing emails and get you closer to your end-goals.

Complaint rate

Complaint rate (a.k.a abuse or spam complaint) measures the number of time recipients reported your marketing emails as unwanted or worse, as spam. Email complaints often occur when a recipient clicks on the TiS button in their email client.

Most ESPs calculate your complaint rate automatically, however, here’s a formula for you to use – 

Email Complaint Rate = (Number of complaints/Total number of emails sent) x 100
Example: 5 complains / 5,500 emails sent x 100 = 0.09%

However, the above formula will not necessarily give you an accurate idea of the complaint rate ISPs are observing. This is due to the fact that not all ISPs have feedback loops set up with ESPs, although all professional ones should.

What’s a good complaint rate? Well, there’s no such thing as a ‘good’ complaint rate. However, an email complaint rate lower than 0.1% (1 complaint for every 1,000 emails sent) is considered to be acceptable – as an industry standard. Any percentage above 0.1 is considered high and may affect not only your email deliverability but also result in your account being suspended by the ESPs.

You can read more about email complaint best practices here >>>

As email marketers, make sure you’re monitoring both your complaint rate as well as your unsubscribe rate simultaneously because some recipients can be lazy and instead of going through the trouble of locating the unsubscribe link and clicking it, they’ll simply hit the spam button. In the event that both email marketing KPIs are showing the same results, take immediate action.

Delivery & Deliverability rates

A delivery rate indicates the number of emails accepted by the recipients’ server. Basically, an email counts as delivered if it didn’t bounce. You can calculate your delivery rate using the following formula – 

Delivery Rate = (Number of emails delivered/Number of emails sent) x 100
Example: 39,000 emails delivered / 40,000 emails sent x 100 = 97,5%

A deliverability rate (a.k.a inbox placement) measures the number of emails that have actually reached the recipient’s inbox or any other folder (except the spam one). This metric is based on the domain’s setup, authentication and reputation. So, if something goes Pete Tong, the burden lies on the shoulders of the ESP from a technical perspective, or your copywriting if the email campaign is filled with spam words – free, best, download now etc!!

Simply because you have 100, 1,000 or 10,000 email addresses on your mailing list(s) doesn’t mean all your emails will be delivered. Achieving a 100% deliverability rate is virtually impossible.

Learn how to improve your deliverability with just a few simple steps >>>

As you can see, delivery and deliverability are two completely different email marketing KPIs. Even if the first one is ‘healthy’, you might still have troubles with the latter.

Email marketing ROI

This particular email marketing KPI is considered to be essential for measuring the success of your email marketing efforts and it also gives you insight into your campaign’s value.

We all probably know what return on investment (ROI) measures. However, just for the sake of it, let’s have a quick reminder. 

ROI is a metric used to evaluate the efficiency as well as the profitability of an investment. In our case, it’s also one of the key email marketing metrics to monitor as it accurately measures the cost-effectiveness of email campaigns. An email marketing ROI shows us how much we earned from our email campaigns in comparison to the costs which we incurred to implement them.

You can calculate your email marketing ROI by using the following formula – 

Email Marketing ROI = [(Value of sales made from an email campaign – Campaign costs)/Campaign costs] x 100
Example: [(£1,500 in sales – £300 in campaign costs)/£300 in campaign costs] x 100 = 400% ROI for the campaign.

We can’t emphasise enough on the fact that email marketing has an ROI of 42:1 which is not only encouraging but also, an excellent reason for those who have yet to leverage this channel should start.  

Final Thoughts

When measuring the success of your email marketing campaigns, data monitoring and analysis are indispensable.

We’ve already outlined ten important email marketing metrics for businesses to keep track of. However, setting clear goals and determining the most relevant email marketing KPIs for your industry is imperative. There might be even more metrics that would suit your business needs better but, by tracking the ones we’ve told you about, you’ll get the most out of every email campaign you send.

Bottom line. Be smart about the email marketing KPIs you are tracking and make sure to effectively measure the individual email performance. After all, an email metric should always provide: valuable data, insight into the recipient’s activity and help you improve your email marketing efforts as well as keep you focused on the end-goal. As long as you track, effectively measure and ‘listen’ to the results of all the listed email marketing KPIs, your email marketing strategy will be on the right track.

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