Images in email: text to image ratio and what works

Images in email are photos, logos, icons and graphics that support the text of a message and show a product, a person or a result. They work well when the email makes sense without them: the main message and the call to action are written as text and the image illustrates them. There is no fixed text to image ratio, roughly 60% text and 40% images is often quoted. The trouble starts with an email made of one large image, which spam filters cannot read and classic Outlook for Windows does not show when the email is opened. In this article you will learn how to balance visual content in email, where images do not show, how to prepare images in six steps and where to find detailed guides on format, size, alt text and image sources.

In brief

1. Write the offer, price, date and call to action as text, the image only illustrates them.
2. An email made of one large image risks spam: in Mailchimp's data, "low ratio of text to image area" was the most common spam finding.
3. According to Litmus, Apple and Gmail have over 90% of opens and show images straight away, Outlook on the desktop, common in companies, blocks them.
4. Prepare a full width image roughly 1,240 px wide and keep the file under 2 MB.
5. Fill in alternative text for every content image, it is shown instead of the image when it does not load.
6. Before sending, send yourself a test email and open it without images and in dark mode.

In short: what images in email are, which types exist, where they do not show and what is at risk

• What it is: the visual content of an email, that is photos, logos, icons, charts and animations next to the text of the message.
• Types: a product or people photo, a logo in the header, icons next to benefits, a chart with results, an animated GIF.
• Where they do not show: in classic Outlook for Windows and Outlook for Mac until the recipient downloads them, and in Gmail in messages it considers suspicious.
• What is at risk: an email without readable text ends up in spam, a recipient without images does not understand the offer and large files load slowly on a phone.

What has changed since the article was published: The original article from June 2017 summarised a survey about visual content in marketing and on social media. In October 2026 we rewrote it as a practical guide to images in email: it now covers the text to image ratio, an overview of email programs that block images, a six step process for preparing images and links to detailed guides. We left out the 2016 and 2017 social media statistics because they were not about email.

What images in email are and what they are for

An image in an email is a file stored on a server that the email program downloads and shows when the message is opened. Unlike text, it is not part of the email itself. If the program does not download it, the recipient sees an empty space or the alternative text instead.

Images in email serve three main purposes:

• Showing what you are talking about: a product, a place, a person or a result that is hard to describe in words.
• Making orientation easier: a logo in the header, icons next to benefits or a chart with numbers help the reader quickly see where they are and what matters.
• Building the brand: the same colours, photo style and logo make a newsletter recognisable.

An image that shows nothing only makes the email longer and slower to load. Leave out a stock photo that would suit any company.

What is the right text to image ratio in an email

The text to image ratio is the relationship between the amount of text in an email and the area taken up by images. No email program or spam filter sets an official value. In practice roughly 60% text and 40% images is often quoted, but it is a guideline, not a rule.

Why the ratio matters: spam filters cannot read text inside an image. Spammers used to exploit this and send emails that were just one large image. Filters therefore treat an email with little text and large images as risky.

Source: Mailchimp, The Most Common Spam Filter Triggers (2009); Litmus, Email Image Blocking: Answering the What, Why, Where, Who, and How (2017, updated 2021).

Mailchimp's data is older, but the principle still holds: today delivery depends mainly on sender reputation, an authenticated domain and recipient interest, and an image only email adds an unnecessary risk on top. More about what decides spam today is in the article What spam is and 4 rules to keep emails out of spam.

Warning: The worst combination is an email where the whole offer, the price and the button are part of a single image. A spam filter finds no text in it, a screen reader reads nothing and in Outlook for Windows the recipient sees only an empty space after opening it.

How many images to put in an email

Put as many images in an email as have a purpose. No verified study gives a fixed number that would apply to a newsletter, an offer and a service message alike. It depends on the type of email and what the recipient should do.

An email that looks like a personal message often works with no images at all. How to write copy people read to the end is covered in the article Email copywriting: how to write copy people actually read.

Where images in email do not show

Image blocking means that an email program does not download images automatically when a message is opened and only shows them when the recipient asks. Microsoft's desktop programs do this most, for security and tracking reasons.

Source: Microsoft, Block or unblock automatic picture downloads in email messages; Google, Gmail Help on images in email; Litmus, Email Image Blocking (updated 2021).

According to Litmus, Apple and Gmail together account for over 90% of tracked opens, so most recipients will see images. Outlook on the desktop, however, is common in companies, so in B2B emails it can block images for a significant share of recipients.

Fill in alternative text for cases when images do not load. In Quanda you can even style it so that a coloured headline appears instead of the image. The steps are in the article Can't see images in an email? Styled alt text shows a headline. How automatic image downloads in Apple Mail affect open rates is explained in the article Apple Mail Privacy Protection: what it changes about open rates.

How to prepare images for an email: 6 steps

You prepare images for an email in six steps: write the main message as text, choose the format, prepare the size, fill in the alternative text, check dark mode and send yourself a test email.

Step 1: Write the main message as text

Write the offer, price, date and call to action in the email text, not in an image, so the recipient sees them even without images. Create the button as a button in the editor, not as a picture of a button. Text in an image is also often too small to read on a phone.

Step 2: Choose the right format

Save photos as JPG, logos and graphics with text as PNG, and animations as GIF. In our measurement the same 1,240 × 827 px photo was 2.0 MB as a PNG and only 242.9 kB as a JPG at 80% quality. WebP, AVIF, SVG and HEIC are not displayed by every email program. A detailed comparison is in the article JPG, PNG or GIF? Which image file type to use for email marketing.

Step 3: Prepare the image size

Crop the image to the aspect ratio of its place in the email, resize it to twice the width of that place and keep the file as small as possible, certainly under 2 MB. The default email width in Quanda is 650 px, a full width image is 618 px after subtracting the margins, so prepare the file roughly 1,240 px wide. Twice the size is needed for high resolution displays such as iPhones and Macs with a Retina display.

The steps in an online editor are described in the articles How to crop an image to a specific size and How to resize an image online.

Step 4: Fill in the alternative text

Write a short alternative text for every image that describes what the image says. Leave the alternative text of decorative images empty. Alternative text (alt text) is a description of an image that the email program shows instead of the image when it does not load and that a screen reader reads aloud. Write "Spring shoe collection 20% off", not "banner1.jpg" or "image".

Step 5: Check dark mode

Try your logo and graphics with a transparent background on a dark background and add a light outline to dark text on a transparent background. Dark mode is a view in which the email program shows an email with light text on a dark background. According to Litmus, some programs do not change colours at all (Apple Mail, Gmail on the desktop), others invert only light areas (Outlook.com, the Outlook mobile app, Gmail for Android) and others invert all colours (Gmail for iPhone, Outlook for Windows). A black logo on a transparent background then disappears on the dark background. How to work with colours is described in the article Colour psychology in marketing: how to get colours on your side.

Step 6: Send yourself a test email

Open the test email on a computer and on a phone, with images on and off, and check the SPAM test result before sending. In Gmail you turn images off in settings with the Ask before displaying external images option. If you cannot tell what the email is about and where to click without images, move the important text out of the images.

Where to get images for an email

You can get images for an email from three sources and each has different advantages:

An overview of stock photo sites with their licences is in the article Free photos for emails: where to find and how to use them, a comparison of tools and a prompting guide in the article AI image generators: a big comparison and prompting guide.

Images in email in Quanda

In Quanda you add images to an email in the email editor with the Image block and change their settings in the right panel. An image always adapts to the space it has in the email. For mobile you can set a separate image width from 10 to 100%, so a logo can be small on a computer and bigger on a phone.

Image dimensions are explained in the guide Image size in an e-mail campaign.

Quanda automatically creates a plain text version of every email, which you can edit in the email editor. The email therefore does not consist only of an HTML part. The SPAM test in the campaign sending settings also scores the text to image ratio: an email with little text and large images gets a worse result. The steps are in the guide Setting up mailing in a simple campaign.

Tip: If you want to design an email with your own code, follow the same rules in HTML: images with alternative text, text as text and code under 102 kB so that Gmail does not clip it. More in the article How to create an HTML email: 7 rules to keep it from breaking.

Image checklist before sending an email

Before sending, check:

• The offer, price, date and call to action are written as text.
• The email is not one big image and makes sense without images.
• Every image has a purpose in the email.
• Photos are JPG, logos and graphics PNG, animations GIF.
• Images are twice the width of their place in the email and no file is over 2 MB.
• Content images have alternative text, decorative ones have it empty.
• The logo is readable in dark mode.
• I have opened the test email on a computer, on a phone and without images.
• The SPAM test reports no problem.

In conclusion

Images help an email when they show something the text cannot and when the email works without them. Write the main message as text, prepare images in the right format and size and always send yourself a test email. If you would like help with your email campaign, write to us at support@onquanda.com, call +420 605 163 892 or book a free consultation. How to work with images across the whole email is covered in the free online course Email Copywriting and Design That Gets Read.