Email Sizes: The Best Practices
Inna Sabada
by Inna Sabada
Email Sizes: The Best Practices

The size of a mailing letter affects the deliverability of an email campaign. This is important for passing spam filters.


Litmus and Salesforce Marketing Cloud jointly conducted a study and it turned out that 45% of recipients unsubscribe from brand promotional emails whose emails do not display well in the email client, and 34% send them to spam. Therefore, you must follow all the rules in order for your email campaign to be successful.


1. Email template size


The universal letter size for email newsletters is 600 pixels wide. The size of the output field differs for different email clients.
Of course, the size of the screen allows you to make the letter larger, but a horizontal scroll may appear - to see all the elements, the user will have to scroll, this is inconvenient.


The height is not strictly regulated, but writing large letters is not effective, now few people want to read large emails.

The universal height is approximately 1000-2000 pixels.

Place the most important information, discounts, and offers at the beginning of the letter, if you immediately interest the reader, he will read the letter to the end.


2. Subject size


One of the most important elements that you need to take time to write.


You will be interested - 14 Tips for Writing an Email Subject


The subject is what recipients see in their inboxes. It depends on it whether the recipient himself will open the email.


In order not to end up in the spam folder, of course, avoid CAPS LOCK and an abundance of exclamation marks.


According to a study by Fluent, Litmus and Adestra, most emails are read from mobile phones. Email clients on smartphones display about 30 subject characters, so it's a good idea to keep it short.


3. Preheader Size


Preheader - the first block inside the letter, the text of which is visible in the list of incoming messages.


The preheader complements the subject, so it should also motivate you to read the letter. Its optimal dimensions:

- text length - up to 140 characters, will no longer fit in the list of incoming letters;
- a height in the template - up to 70 pixels, higher preheaders attract too much attention.


4. Header size


Header - the heading of the letter, which is displayed inside. This is usually a title that promises to benefit from reading - in the template it takes up a height of 50-65 pixels.


The header width is usually 600 pixels: the same as the classic email template width.


5. Banner size


Placing a banner on the mailing list contributes to a high CTR. It includes an image, text, customer benefit in the form of a discount and its expiration date, and a CTA button.


The maximum width is up to 600 pixels.
The most common banner heights are 300px and 400px but can be higher especially if the email is aimed at mobile readers.


6. Image size


Not only the size is important here, but also the weight. The heavier the image, the longer it will take to load on the screen, which will cause irritation.


The height should be proportional to the width of the template at 600px and the best size is 480px.

But if the letter is targeted at mobile users, other sizes are acceptable: for example, 250x500. The main thing is to follow the same rule as for banners: so that the image fits completely on any screen.


The optimal weight of images is up to 100-200 Kb. It is best to use 1 picture in the email.


7. Text size

In the text, not only the size is important, but also the font used: it also affects perception.

The maximum size of a text block is 600 pixels. The number of characters in one line is up to 75: with more characters, words may not wrap correctly on a new line. The amount of text does not affect the size of the letter, but its font, and color - directly. And remember the simple rule: the more text, the less likely it is to be read.


It is better to use generally accepted fonts for letter layouts because they are easy to read on all devices. Decorative fonts may not be on the user's smartphone or computer: then the system will automatically convert it to the standard Arial type.


8. CTA Button Size


There are no hard and fast rules on size.

The most important thing is to highlight it against the rest of the background and make it noticeable.

Learn more about the CTA button - Call to action. Rules.


You can use different sizes: 46x46, 120x60, 175x35 pixels, and so on. Someone puts one word on it, someone - a phrase or a whole sentence. The main thing is that the button is fully visible on the screen, and the text does not “leave” it.


9. Footer size

Footer - the "basement" of the letter, the lowest block. Its classic content is contacts, social media icons, and an unsubscribe link. This fits into a 600x200 pixel block.


10. Attachment size

Attachments - what is attached to the letter: presentations, PDF documents, individual images. It's not the size that matters, but the weight. The optimal weight of attachments is up to 5 MB.


11. Full email size

The size of an e-mail is determined by the rules of etiquette in correspondence: its weight should not exceed 200-500 Kb.

E-mail clients have even tougher restrictions: the optimal weight of a letter without attachments is up to 100 Kb. Gmail truncates content over 102 KB - Auto all-in-one tool to make your email channel reliable | Product Hunt