Email open rate: definition, calculation and best practices to improve your campaigns

What is open rate?

Definition of open rate

Open rate is the percentage of recipients who opened an email out of those who actually received it. It is one of the long-standing metrics of email marketing, used to measure how appealing a campaign is in the first minutes after it is sent.

In practice, when a recipient opens an email, an invisible image (called a tracking pixel) is loaded. It is this loading that allows email platforms to record an open.

Open rate therefore doesn't measure whether the content was actually read. Someone can open an email for a few seconds without reading it, and some opens can be recorded automatically by privacy protection systems.

Good to know

Since Apple Mail Privacy Protection was introduced, some opens are generated automatically, without any action from the user. Open rates should therefore be interpreted with more caution.

Why does this metric matter in email marketing?

Open rate is an excellent indicator of the first impression your campaign makes.

Even before you assess the quality of the content or the sales performance of an email, it tells you whether recipients wanted to open it.

A low open rate can reveal several problems:

• an unengaging subject line;
• a sender who doesn't inspire trust;
• poor deliverability;
• an aging contact list;
• excessive sending frequency.

Conversely, a good open rate generally shows that your message is arriving at the right time, to the right audience, with a sufficiently attractive promise.

For companies growing their acquisition through email or through a B2B prospecting agency, this metric is often the first signal for assessing a campaign's quality before analyzing more advanced sales performance.

What role does open rate play in a marketing strategy?

Open rate is not an end in itself. It is a steering metric that helps you optimize your campaigns step by step.

It can be used in particular to:

• compare several email subject lines;
• identify the best sending times;
• measure the impact of a new segmentation;
• track changes in sender reputation;
• detect a decline in database quality.

Tracked over time, it shows which practices genuinely improve performance.

For example, a company may find that systematically personalizing the subject line raises its open rate by several points, or that changing the sender name causes results to drop sharply.

The goal isn't just to get a high number, but to identify the levers that have a lasting influence on email performance.

How do you calculate open rate?

The formula

The calculation is fairly simple.

Open rate = (Number of emails opened ÷ Number of emails delivered) × 100

It is important to use the number of emails delivered rather than the number of emails sent.

Rejected emails (hard bounces or soft bounces) should not be included in the calculation, since they never reached the inbox.

Summary table

Total open rate vs unique open rate

Not all platforms calculate open rate the same way.

There are generally two metrics.

The unique open rate is generally the most relevant for measuring a campaign's ability to spark interest among its audience.

The total open rate, for its part, can give some indication of engagement when an email is viewed several times.

Open rate calculation example

Let's take a concrete example.

A company sends a campaign to 5,000 contacts.

The results are as follows:

• 5,000 emails sent;
• 4,850 emails delivered;
• 1,552 unique opens.

The calculation is therefore:

(1,552 ÷ 4,850) × 100 = 32%

The open rate is therefore 32%.

This figure should then be compared with:

• previous campaigns;
• averages in your industry;
• other metrics such as click-through rate and conversion rate.

Good to know

A higher open rate doesn't automatically lead to more sales. A very attractive subject line can generate more opens while producing few clicks if the content of the email doesn't live up to the expectations it created.

What factors influence open rate?

Open rate rarely comes down to a single element. Several factors combine to determine whether a recipient will open your email or not.

Understanding these levers helps you optimize your campaigns step by step, without limiting yourself to choosing a subject line.

The email subject line

The subject line is the first thing visible in the inbox.

In a few dozen characters, it must spark enough curiosity to prompt an open, without resorting to exaggerated promises.

The best-performing subject lines are generally:

• clear;
• specific;
• benefit-oriented;
• tailored to the target audience.

Conversely, overly salesy wording, capital letters or excessive punctuation increase the risk of being ignored… or even flagged as spam.

The sender name

Before even reading the subject line, many recipients look at who sent the email.

A recognizable sender name inspires more trust than a generic address.

For example:

• Sophie Martin — Oliverlist
• Olivier at Oliverlist

will often perform better than:

• noreply@
• marketing@
• contact@

A consistent sender name also helps build brand recognition from one campaign to the next.

The preheader

The preheader is the text that appears just after the subject line in most email clients.

It is a second opportunity to win the reader over.

Rather than letting automatic text such as "If you can't see this email..." appear, use this space to complement the promise made in the subject line.

The subject line and preheader should work together to spark curiosity while remaining consistent.

Email deliverability

Even the best subject line won't produce any results if your emails never reach the inbox. Deliverability is therefore a prerequisite for a good open rate.

It depends on many criteria, including:

• the reputation of your sending domain;
• email authentication (SPF, DKIM and DMARC);
• sending volume;
• the spam complaint rate;
• the bounce rate.

Email providers such as Gmail, Outlook and Yahoo assign a trust score to every sender. If that score deteriorates, your campaigns may be routed to the spam folder or even blocked.

For companies that use cold email, maintaining an excellent sender reputation is essential to preserve campaign performance over time.

Good to know

According to several industry studies, nearly one in six commercial emails never reaches the recipient's main inbox. Good deliverability can therefore have more impact on results than simply optimizing the subject line.

The quality of your contact list

A campaign's performance depends first and foremost on the quality of your database.

A recent, qualified and regularly updated contact list naturally generates more opens than an aging one.

Conversely, several factors quickly drag performance down:

• outdated addresses;
• contacts who have been inactive for years;
• rarely checked generic addresses (contact@, info@...);
• recipients who have never shown any interest in your content.

This is also why buying email lists is strongly discouraged. These lists often contain poorly qualified or outdated addresses, or spam traps that can permanently damage your sender reputation.

Send time

Timing has a direct influence on open rate.

An excellent email sent at the wrong time can go completely unnoticed in a crowded inbox.

There is, however, no universal time slot.

The best time depends in particular on:

• the industry;
• the recipients' profile;
• the time zone;
• email-checking habits.

In B2B, campaigns often perform well on weekdays, especially early in the morning or late in the afternoon. Some industries, however, see excellent results on Sunday evenings or very early on Monday mornings.

The best approach is to test different send times and analyze performance across several campaigns.

You can explore this topic further in our guide on when to send a prospecting email, which details the best-performing time slots for different contexts.

Audience segmentation

Sending the same message to your entire database is rarely the most effective strategy.

Segmentation means tailoring campaigns according to specific criteria:

• industry;
• company size;
• job function;
• time in the database;
• interaction history;
• purchasing behavior.

The more relevant the content is to the recipient, the higher the chances of an open.

Take the example of a SaaS vendor. A campaign aimed at sales managers won't use the same arguments as an email targeting SMB owners.

This personalization improves not only open rate, but also clicks and conversions.

What is a good open rate?

It is tempting to compare your open rate with a benchmark figure. Yet there is no universal threshold.

Performance varies depending on the industry, the type of campaign, the quality of the contact list and the sender's brand awareness.

The most relevant approach is to track how your own results evolve over time while comparing them with the averages observed in your market.

Averages by industry

Some industries naturally enjoy higher open rates than others.

For example, non-profits and training organizations often have very engaged audiences, while highly competitive industries record more modest performance.

Table — Indicative averages by industry

These figures are reference points. They can vary depending on the email platform, data quality and the impact of Apple Mail Privacy Protection.

Differences between B2B and B2C

B2B campaigns generally show higher open rates than B2C campaigns.

Several reasons explain this difference.

In B2B:

• lists are often smaller;
• messages are more targeted;
• recipients receive fewer sales solicitations than consumers;
• needs are often more specific.

In B2C, competition in the inbox is much fiercer.

Consumers can receive dozens of promotional emails every day, which mechanically lowers open rates.

This doesn't mean a B2C campaign performs worse. Sending volumes and marketing objectives are often very different.

Factors that explain differences in performance

Comparing a percentage on its own can lead to the wrong conclusions.

Two companies in the same industry can get very different results depending on several criteria.

The main factors include:

A company sending highly targeted campaigns to a qualified audience will generally get better results than a brand sending the same message to tens of thousands of disengaged contacts.

Good to know

Trying to beat market averages is rarely the best goal. Steady improvement in your own performance is a far more meaningful indicator than a comparison with generic benchmarks.

How can you improve your open rate?

Improving your open rate doesn't depend on a miracle trick. The best results generally come from a combination of best practices applied consistently.

The best-performing companies continuously optimize their subject lines, segmentation, sender reputation and the quality of their contact list.

Write better-performing subject lines

The subject line is the main trigger for an open.

In just a few words, it must convince the recipient that your email deserves their attention.

The best subject lines favor clarity, relevance and an explicit promise over deliberately mysterious wording.

Best practices

The subject lines that generate the best results often share several characteristics:

• clearly state the benefit;
• stay concise (40 to 60 characters);
• spark curiosity without manipulating;
• use a natural tone;
• personalize when it adds real value;
• avoid words associated with spam.

A few examples:

• How can you improve your open rate?
• Three mistakes that hurt your email campaigns
• Does your campaign deserve a second send?

Mistakes to avoid

Conversely, some subject lines sharply reduce performance:

• excessive use of capital letters;
• too many emojis;
• misleading promises;
• excessive punctuation ("!!!");
• overly vague subject lines ("Important information").

When the subject line doesn't reflect the actual content of the email, recipients quickly lose trust, which drags down the performance of subsequent campaigns.

Personalize your campaigns

Personalization is often reduced to adding the first name in the subject line or the body of the message. Yet effective personalization goes much further.

The goal is to send an email that feels as though it was written for its recipient. That requires a better understanding of your audience and using the data you have.

You can personalize, in particular:

• industry;
• the contact's job function;
• company size;
• business challenges;
• the content offered;
• calls to action.

For example, a sales director and a marketing manager don't have the same expectations. Tailoring your message to their context naturally increases the chances of an open, as well as clicks and conversions.

Personalization is particularly effective when it is built on a B2B lead generation strategy, where each campaign addresses an identified challenge rather than an overly broad audience.

Segment your database

Segmentation is one of the most powerful levers for improving campaign performance.

It means splitting your contacts into homogeneous groups so you can send more relevant messages.

The most commonly used segmentation criteria are:

• industry;
• company size;
• location;
• job title;
• sales maturity;
• engagement with previous campaigns.

The finer your segmentation, the more relevant your communication becomes.

Conversely, sending the same email to thousands of contacts with very different profiles generally leads to a gradual decline in opens and clicks.

Optimize your sender reputation

Email providers constantly assess the reputation of the domains and addresses that send emails.

A poor reputation reduces the visibility of your campaigns, even if their content is high quality.

To protect this reputation:

• increase your sending volumes gradually;
• avoid sudden spikes in campaigns;
• remove invalid addresses quickly;
• limit spam complaints;
• monitor your bounce rates;
• authenticate your domain properly.

Companies that scale their prospecting with sales automation pay particular attention to this reputation, because it directly determines campaign deliverability.

Clean your contact list regularly

A database naturally deteriorates over time.

People change companies, some addresses become inactive and others no longer read the emails they receive.

Regular cleaning helps you:

• reduce bounces;
• improve deliverability;
• maintain a good reputation;
• get more representative statistics.

It is recommended to identify contacts who have been completely inactive for several months and run re-engagement campaigns before removing them.

This often improves overall performance without sending more emails.

Good to know

A smaller but engaged database generally produces better results than a large one made up of inactive contacts. Email providers take recipient engagement into account in their algorithms.

Test with A/B testing

A/B testing means comparing two versions of the same email to identify the one that performs best.

The elements most frequently tested are:

• the subject line;
• the sender name;
• the preheader;
• the send time;
• the send day.

To get reliable results, it is essential to change only one element at a time.

Example

After sending to a representative sample, the best-performing version is then sent to the rest of the database.

This method lets you improve results step by step through data-driven decisions rather than gut feeling.

Mistakes that make open rates drop

Some practices directly hurt the performance of email campaigns.

Identifying them often leads to quick improvements.

Buying email lists

Buying an email database may seem like a quick way to expand your audience.

In reality, this practice generally leads to:

• poorly relevant contacts;
• more bounces;
• more spam reports;
• a deteriorating sender reputation.

The consequences can last for weeks or even months.

To understand the risks associated with this practice, read our article on buying an email database.

Sending campaigns too often

Sending frequency strongly influences recipient behavior.

Campaigns sent too close together often lead to:

• fewer opens;
• more unsubscribes;
• more spam complaints.

Conversely, sends that are too far apart can weaken recognition of your brand.

The goal is therefore to find a rhythm that matches your audience's expectations.

Using misleading subject lines

Deliberately sensationalist subject lines can generate more opens in the short term.

However, when the content doesn't match the promise made, the consequences are often negative:

• loss of trust;
• fewer clicks;
• more unsubscribes;
• a damaged reputation.

The subject line should create curiosity without manipulating the reader.

Neglecting email authentication (SPF, DKIM, DMARC)

The SPF, DKIM and DMARC protocols allow email providers to verify that an email really comes from the domain it claims to.

Without these mechanisms:

• more emails are classified as spam;
• some messages are rejected;
• your reputation may be affected.

Today, these protocols have become essential for any serious email strategy.

The limits of open rate

For many years, open rate was the benchmark metric for email campaigns.

Today, interpreting it calls for more caution.

Changes in privacy protection tools have profoundly changed the way opens are counted.

Why this metric has become less reliable

Open tracking has historically relied on an invisible pixel loaded when the email is displayed.

However, some email providers now automatically download these images to protect their users' privacy.

The result:

• some opens are recorded even though the email was never read;
• it becomes difficult to tell genuine interactions from automatic opens.

Open rate therefore remains useful for tracking trends, but should no longer be interpreted as an exact measure of actual reading.

The impact of Apple Mail Privacy Protection (MPP)

Since iOS 15, Apple has offered the Mail Privacy Protection (MPP) feature.

When it is enabled, Apple automatically downloads the images contained in emails, including the tracking pixel.

In practice, this means that:

• opens can be counted even if the user never viewed the message;
• some open rates appear artificially high;
• comparisons between different audiences become more complex.

This change affects a large share of Apple users and explains why many platforms now recommend giving more weight to clicks and conversions.

Why you should analyze other KPIs as well

Open rate is still an interesting metric, but on its own it can't tell you whether a campaign succeeded.

A complete analysis relies on several complementary KPIs.

To go further, it is recommended to also track prospecting KPIs in order to assess the real performance of your campaigns, from the open all the way to the creation of sales opportunities.

The goal is no longer just to get opens, but to measure the real impact of your emails on your business.

Which metrics should you track alongside open rate?

Open rate is a good visibility indicator, but on its own it can't tell you whether an email campaign succeeded.

To measure the real effectiveness of your emails, it is recommended to analyze several complementary KPIs. Together, they give a much more precise view of your recipients' behavior and the performance of your strategy.

Click-through rate (CTR)

Click-through rate (CTR) measures the percentage of recipients who clicked on at least one link in your email.

Unlike open rate, it reflects a concrete action by the user.

The formula is:

CTR = (Number of clicks ÷ Number of emails delivered) × 100

A high open rate combined with a low CTR can reveal a gap between the promise of the subject line and the content of the email.

Conversely, a good CTR shows that your message sparks genuine interest.

Click-to-open rate (CTOR)

Click-to-open rate (CTOR) measures the percentage of recipients who clicked after opening the email.

Its formula is:

CTOR = (Number of clicks ÷ Number of opens) × 100

This metric lets you assess the quality of your email content independently of the subject line.

A low CTOR may signal:

• unconvincing content;
• a call to action that is hard to see;
• poorly organized information;
• an offer that doesn't meet the expectations set by the subject line.

Conversion rate

The real goal of an email campaign isn't just to generate opens or clicks.

What really counts is the action taken after the click.

Depending on your goals, a conversion can be:

• a booked meeting;
• a demo request;
• a white paper download;
• a sign-up;
• a purchase;
• an account creation.

Conversion rate is generally the most relevant metric for measuring the return on investment of your campaigns.

Bounce rate

Bounce rate is the percentage of emails that could not be delivered.

There are two categories:

A high bounce rate gradually erodes the reputation of your sending domain.

It is therefore essential to regularly remove invalid addresses from your contact list.

Unsubscribe rate

Unsubscribe rate measures the proportion of recipients who choose to stop receiving your emails.

A few unsubscribes are perfectly normal.

A sudden increase, however, can reveal several problems:

• excessive sending frequency;
• insufficient targeting;
• irrelevant content;
• promises that weren't kept.

Monitoring this metric lets you adjust your strategy before your domain's reputation takes a hit.

Good to know

A campaign can show an excellent open rate while generating a large number of unsubscribes. That's why it is essential to analyze several KPIs at the same time rather than a single metric.

Tools for measuring open rate

Performance tracking is now built into most email marketing solutions.

These platforms let you view opens, clicks, conversions and many other metrics in real time.

Email marketing platforms

Email solutions generally offer comprehensive dashboards for tracking:

• open rate;
• click-through rate;
• conversion rate;
• bounces;
• unsubscribes.

They also offer A/B testing, segmentation and campaign automation features.

Marketing automation tools

Marketing automation platforms go further than just sending emails.

In particular, they let you:

• create automated workflows;
• trigger campaigns based on user behavior;
• score prospects;
• track their progress through the conversion funnel.

These tools make it easier to analyze the full prospect journey, from opening an email to signing a contract.

CRM with performance tracking

Modern CRMs let you connect email statistics with sales results.

This approach provides a far more meaningful view than simply tracking opens.

For example, you can measure:

• the number of opportunities created;
• the meetings booked;
• the sales generated;
• the revenue attributable to campaigns.

For sales teams, this view is essential for identifying the actions that actually generate results.

Conclusion

Open rate remains an essential metric for assessing the visibility of your email campaigns. It quickly shows the impact of a subject line, a sender or a segmentation on the performance of your sends.

However, this KPI should no longer be analyzed in isolation. Changes in privacy protection technologies, particularly Apple Mail Privacy Protection, now call for a more nuanced reading of the results. To manage your strategy effectively, it is essential to cross-reference open rate with click-through rate, CTOR, conversion rate and other performance metrics.

By applying the best practices presented in this guide — better subject lines, segmentation, database cleaning, deliverability optimization and A/B testing — you will have every lever you need to durably improve your email campaigns and maximize their sales impact.

Open rate FAQ

How do you calculate open rate?

Open rate is calculated by dividing the number of emails opened by the number of emails delivered, then multiplying the result by 100.

Open rate = (Emails opened ÷ Emails delivered) × 100

What is a good email open rate?

There is no universal value.

As a general rule:

• a rate below 20% may reveal a targeting or deliverability problem;
• between 20% and 30%, performance is decent in many industries;
• above 30%, campaigns are often considered high-performing, especially in B2B.

What matters most, however, is comparing your results with those of your previous campaigns.

Why is my open rate low?

Several factors can explain a low open rate:

• an unappealing subject line;
• a poor sender reputation;
• an outdated contact list;
• deliverability problems;
• insufficient segmentation;
• an unsuitable sending frequency.

Before changing your campaigns, also check that your emails are actually reaching the inbox.

How can you increase your open rate quickly?

The quickest gains generally come from the following actions:

• reworking your email subject lines;
• improving the preheader;
• segmenting your audience further;
• cleaning your contact list;
• testing several send times;
• running A/B tests.

Lasting improvement, however, depends on an overall strategy rather than a one-off optimization.

Is open rate still a reliable KPI?

Open rate remains useful for identifying trends and comparing several campaigns.

However, it has become less accurate since the arrival of Apple Mail Privacy Protection (MPP), which can record automatic opens without any action from the user.

It is therefore recommended to complement your analysis with click-through rate, CTOR and conversion rate.

What is the difference between open rate and click-through rate?

Open rate measures the number of recipients who opened the email.

Click-through rate measures the number of recipients who clicked on a link in that same email.

The first assesses how appealing your campaign is, while the second measures your audience's genuine engagement.