What open rate is and how it is calculated
Open rate is the ratio of unique opens to delivered messages, expressed as a percentage. It sounds simple, but in practice almost every tool calculates it a little differently, and that is the first source of confusion in teams.
The basic formula looks like this:
Open rate = (unique opens / delivered emails) × 100%
Three elements of this formula need a comment. First, unique opens, not all opens. If the same recipient opens an email five times, it counts once. Some tools also show "total opens", which can be several times higher and are misleading when comparing campaigns.
Second, delivered, not sent. Bounced emails should not go into the denominator, because they never had a chance to be opened. If your system calculates open rate from sent emails, you are understating your result by a few percentage points for no reason.
Third, the measurement mechanism itself. Most email marketing tools insert an invisible tracking pixel into the content. An open is recorded when the email client downloads that image. If the recipient has images disabled (the default in many email clients, especially Outlook), the email may be read but the open is not recorded. Conversely, automatic previews in Gmail or Apple Mail can generate false opens that no human ever saw.
Practical conclusion: open rate is a directional indicator, not a laboratory measurement. It is suitable for comparing your own campaigns against each other over time, but comparing it across companies and tools can be unreliable. If you are building B2B lead generation on data, this uncertainty needs to be factored into decisions.
What actually influences email open rates
When someone asks how to increase open rate, they usually expect a list of tricks. In reality, the result is made up of several layers, and some of them work before the message is even sent.
Deliverability and sender reputation
The most important layer. If emails land in spam or the "Promotions" tab in Gmail, open rate will be close to zero no matter how brilliant your subject line is. Sender reputation is built by the technical configuration of the domain (SPF, DKIM, DMARC), sending history, spam complaint rate, and whether recipients reply and click. This is foundational work, invisible in reports but decisive. We cover how to take care of email deliverability in a separate article.
Sender recognition
An email from an unknown person at an unknown domain has a much lower chance of being opened than a message from someone who has previously appeared on LinkedIn, at a webinar, or in a conversation. In B2B, the decision to open is made in a fraction of a second and is based mainly on whether the sender's name means something. That is why cold email campaigns work better when they are preceded by any trace of presence.
Subject line and preheader
The subject line is the most frequently mentioned factor, but its impact is often overestimated. A short, specific subject line without clickbait works better than a long, "salesy" one. The preheader (the first sentence visible in the inbox next to the subject) often matters more than the subject itself, because it extends or breaks the promise from the subject. If the preheader is a random fragment of the footer, you are wasting the second most important field in the entire email.
Audience fit and timing
An email sent to someone who is not a decision-maker in that area will have a low open rate regardless of the content. The same applies to emails sent on Friday after 4 pm or in the middle of the holiday season. It is about whether you reach the recipient at a moment when the topic is relevant to them.
| Campaign type | Lower bound | |
|---|---|---|
| Newsletter to your own database | 20% | 35% |
| Cold email to a machine-generated list | 2% | 8% |
| Cold email to a matched list | 8% | 20% |
| Email to a warm lead | 30% | 50% |
| Transactional email | 50% | 70% |
These layers work in sequence. Improving the subject line when deliverability is poor will not help. Improving deliverability with a poorly chosen list will have limited effect. The order matters, and this is the most common mistake in optimization.
What are realistic open rate ranges in B2B
The honest answer is that there is no single number that can be considered good for everyone. Ranges vary between industries, sales models, and list types. Below are typical ranges observed on the market, with the caveat that these are indicative values, not hard benchmarks.
| Campaign type | Typical open rate | Notes |
|---|---|---|
| Newsletter to your own database | 20-35% | Depends on list engagement and sending frequency |
| Cold email to a purchased or machine-collected list | 2-8% | Low list quality significantly lowers the result |
| Cold email to a matched list (ICP, research) | 8-20% | Large variance depending on industry and region |
| Email to a warm lead after contact | 30-50% | The recipient knows the sender |
| Transactional email (confirmations, invoices) | 50-70% | High open rate, but a different purpose |
One thing is worth noting: open rates for B2B cold emails rarely exceed 20% on a repeatable basis, and values above 30% on a cold list usually mean either that the list is not as cold as it seems, or that the measurement is distorted (for example, by automatic previews).
Instead of comparing yourself to general benchmarks, it is better to establish your own baseline. Measure the average of your last 5-10 campaigns to a similar audience and treat it as your reference point. Then you can see whether a change in subject line, list, or send time actually improved anything. This approach is far more useful than chasing numbers from the internet.
How to increase open rate: specific actions
Below is a list of actions ranked from those with the greatest impact to those with the smallest. The order is not random.
1. Sort out deliverability
- Configure SPF, DKIM, and DMARC for your sending domain. Without this, some emails will not arrive.
- Separate your sending domain from your main company domain. If cold mailing damages its reputation, it will not drag down communication with your clients.
- Regularly remove addresses that generate bounces and spam reports from your list.
- Warm up new sending domains gradually, starting with small volumes.
2. Improve list quality
Open rate depends heavily on list relevance. If you send to people who have nothing to do with your offer, no subject line will fix that. Narrow your criteria to specific job titles, industries, and buying signals. A smaller, better-matched list usually delivers a higher open rate than a large list kept "just in case".
3. Work on the subject line and preheader
- Keep the subject line within 4-7 words. Longer ones often get cut off on mobile.
- Avoid typical spam words: "free", "promotion", "guarantee", "!!!".
- Test subject lines without emoji and with emoji separately, do not mix variants in one test.
- Treat the preheader as the second sentence of the subject line, not as a random fragment of content.
- Run A/B tests on a representative sample (minimum 500-1000 recipients per variant), otherwise the results are noise.
4. Build recognition before sending
Before you send an email, make sure the sender name is at least somewhat familiar. This can be activity on LinkedIn, a comment under the recipient's post, a mention at a webinar, or contact through a mutual acquaintance. This action will not produce an immediate effect in a single campaign, but over a few months it raises the open rate of your entire base.
-
1
Deliverability
SPF, DKIM, DMARC, domain warm-up, cleaning the list of bounces
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2
List quality
Narrowing criteria to job titles, industries, and buying signals
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3
Subject line and preheader
A/B tests on a representative sample, short subject lines without spam words
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4
Sender recognition
LinkedIn presence, webinars, contact through mutual connections before sending
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5
Content segmentation
Context personalization, not just the first name in the subject line
5. Segment and personalize at the content level
Personalizing the first name in the subject line is already standard and does little on its own. Context personalization brings more: a reference to the recipient's industry, to a specific problem, to an event in their company. This requires work when building the list, but it translates into a higher email open rate in subsequent campaigns.
6. Set a sending rhythm and stick to it
Recipients get used to a sender who appears regularly. Irregular sends, once a quarter, once a week, lower recognition and open rate. It is better to send less often, but consistently.
What open rate will not tell you about a campaign
Open rate is an entry-level metric. It says that someone opened the email, but it does not say whether they read it, understood it, clicked, or replied. In B2B, the real value is in replies and meetings, not opens. Imagine a salesperson opening a report on Monday morning: open rate 34%, but zero replies. They call the client, and the client says: "I saw the email, but I did not have time to reply." The opposite also happens: a campaign with an open rate of 12% generates more meetings than a campaign with an open rate of 25%, because it reaches a better-matched group.
That is why open rate is worth reading together with other metrics: click-through rate (CTR), reply rate, number of meetings, and cost per lead. On its own it is useful as a warning signal when it suddenly drops, but not as a goal in itself.
If open rate drops while the number of replies grows, you have probably narrowed the list to better-matched recipients, and that is a good direction. If open rate grows while meetings do not increase, you may be attracting curious onlookers who are not your customers. It is worth keeping this in mind when planning a B2B marketing strategy based on data, not on a single metric.
In practice, teams that manage open rate well do two things: they measure it consistently according to one definition and connect it with business metrics. The rest is iteration and patience.
