Thumbnail: what it is, what it means and recommended sizes
What a thumbnail is, how to design one and what size to use on each platform
In the context of online marketing and advertising, a thumbnail is a reduced and compressed version of an image or video.
Thumbnails are commonly used on social media and video platforms such as YouTube to display a preview of the content before the user clicks on it.
Thumbnails are a key element in digital marketing, as they are often the first interaction a user has with the content.
An attractive and relevant thumbnail image can significantly increase click-through rates and user engagement.
In addition, thumbnails are also important for search engine optimization (SEO), as smaller, compressed images load faster, thus improving the user experience and possibly the content’s SEO ranking.
Remember that although thumbnails are small, they can have a big impact on the effectiveness of your digital marketing efforts.
What does thumbnail mean?
The word thumbnail literally means the nail of your thumb. As a design term, it means a miniature: a small image that represents a larger image, a video or a page.
You use them every day without realizing it: the cover images of YouTube videos, photo previews on your phone, the images on blog posts or the products in an online store.
Make your emails just as eye-catching
Create newsletters with images, buttons and templates in a drag-and-drop editor.
Benefits of thumbnails
Despite their small size, thumbnails carry a lot of weight in digital marketing and offer a number of significant benefits.
Here are some of the most important advantages of thumbnails:
- Increased click-through rate (CTR): a well-designed thumbnail can capture users’ attention and encourage them to click on your content. This can result in an increased click-through rate, which is an important factor in search engine optimization and social media algorithms.
- They help to improve user experience: Thumbnails provide a visual preview of the content, which helps users decide whether to click or not. This can improve user experience, allowing them to find the content they are interested in more quickly and easily.
- Bandwidth efficiency: as thumbnails are reduced versions of the original images or videos, they use less bandwidth during loading. This can improve the loading speed of your website or app, which can have a positive impact on SEO rankings and user satisfaction.
- It can improve search engine visibility: Thumbnails can also be indexed by search engines, which can help your content to be displayed in image search results. This can increase the visibility of your content and drive more traffic to your site or platform.
- Branding and brand recognition: You can use thumbnails to reinforce your brand identity. For example, you can use consistent colors, fonts and image styles that reflect your brand. This can make your thumbnails instantly recognizable and help build the perception of your brand.
In conclusion, thumbnails are a small but powerful digital marketing tool.
A good thumbnail design can improve visibility, engagement and user experience, while also helping to strengthen your brand recognition.
Thumbnail design strategies
Effective thumbnail design is an art that combines aspects of marketing, psychology and graphic design.
Here are some strategies for designing attractive and effective thumbnails:
- Use high-quality images: a blurry or pixelated thumbnail can give the impression that your content is also of poor quality. Always use high-resolution images in thumbnails.
- Opt for bright, contrasting colors: Bright, contrasting colors can make thumbnails stand out on a page full of other videos or images. Consider your brand’s color palette, but don’t be afraid to experiment with eye-catching colors.
- Include readable text: if you decide to include text in thumbnails, make sure it is large and clear so that it is easily readable even at a small size. Avoid using too much text. One or two keywords or a short phrase are usually enough.
- Try including human faces: human faces can attract users’ attention, especially if they show strong emotions. If your video or content has a presenter or main character, consider including their face in the thumbnail.
- Brand consistency: if you’re designing thumbnails for a series of videos or for all your online content, maintaining a consistent style can help users recognize your brand. This can include using certain colors, fonts, image styles or even including your logo.
- Create intrigue: a good thumbnail can arouse a user’s curiosity and encourage them to click to see more. Think about how you can use thumbnails to suggest the value or interest of your content without giving everything away.
- Test and optimize: finally, as with any marketing strategy, it’s important to test different thumbnails and see what works best with your audience. Data such as click-through rates and page views can help you understand which types of thumbnails are most effective.
When designing thumbnails, always consider your target audience and what will appeal to them.
A good thumbnail reflects the content it represents, attracts users’ attention and invites them to click to find out more.
Recommended thumbnail sizes
| Where | Recommended size | Format and file size |
|---|---|---|
| YouTube video | 3840 × 2160 px (16:9), minimum 640 px wide | JPG or PNG, up to 2 MB from a phone and 50 MB from a computer |
| YouTube Shorts | 2160 × 3840 px (9:16) | JPG or PNG |
| Blog or website | Depends on the template: 1200 × 675 px (16:9) is common | Compressed JPG or WebP |
| 600 px visible width (upload the image at 1200 px for retina screens) | Lightweight JPG or PNG |
To upload custom thumbnails to YouTube, your account must be verified. YouTube sizes checked in its Help Center in October 2026.
Tools for creating thumbnails
Creating an attractive and effective thumbnail doesn’t have to be a complicated task.
There are several online tools, both free and paid, that can help you create professional thumbnails.
Here are some of the most popular options:
- Canva: This is an online graphic design tool that is very easy to use. Canva offers a variety of thumbnail templates that you can customize with your own images, text, and colors. In addition, Canva has a fairly generous free version and a paid version with additional features.
- Adobe Express (formerly Adobe Spark): This is another online thumbnail maker that lets users create custom designs easily. Adobe Express has an intuitive interface and a wide selection of templates and graphic resources.
- Snappa: Snappa is an online graphic design tool that includes a specific feature for creating YouTube thumbnails. Like the other tools, Snappa offers a variety of templates that can be customized to your preference.
- PicMonkey: PicMonkey is an online photo editor that can also be used to create thumbnails. It offers a wide range of image editing features, as well as design templates.
- Photoshop: If you have more graphic design skills, you might want to consider using Adobe Photoshop. Although this is a paid tool and has a steeper learning curve, it offers the greatest flexibility and a very comprehensive set of tools for creating thumbnails.
These are just a few of the many tools available for creating thumbnails.
Each has its pros and cons, so the best option will depend on your specific needs, skill level and budget.
Thumbnails and email marketing
Thumbnails also play an important role in email marketing.
Although we traditionally associate thumbnails with video platforms such as YouTube, their use in emails can significantly improve click-through rates and user interaction.
For example:
- Visual appeal: emails with attractive visual elements, such as thumbnails, tend to have higher click-through rates. Thumbnails can provide a preview of a piece of content (such as a video, a blog post, a product, etc.) and encourage the reader to click through to see more.
- Increased interaction: including a video thumbnail can increase user interaction. A thumbnail with a play icon invites people to click and watch the video.
- Improved user experience: thumbnails can make an email easier to scan and understand quickly. This can improve the user experience, allowing them to quickly identify the content they are interested in.
- Branding and brand recognition: as with other digital channels, thumbnails in emails can reinforce your brand identity. Consistent and recognizable thumbnails can help readers identify your emails and associate them with your brand.
Therefore, while thumbnails are perhaps best known for their use on video platforms, they are also a valuable tool in email marketing.
As always, it’s important to test and optimize thumbnails to understand what works best with your audience.
How Mailrelay helps you
A video won’t play inside an email. What works is a video thumbnail with a play button, linked to YouTube or your website. With Mailrelay you can do it like this:
- Drag-and-drop editor, to place the thumbnail and link it to the video, an article or a product.
- Responsive templates that adapt images to mobile.
- Click statistics per link (on the free account and Enterprise), so you know which thumbnail gets the most clicks.
- A/B testing, to compare two versions of an email before sending it to your whole list.
The free account includes 80,000 emails a month and up to 20,000 contacts.
Design newsletters with images that invite clicks
Measure which images and links get the most clicks in each campaign.
Frequently asked questions
What is a thumbnail?
It’s a small image that serves as a preview of a larger image, a video or a page. Its purpose is to show people what they’ll find so they can decide whether to click.
Where does the word thumbnail come from?
It refers to a miniature. The name comes from the literal thumbnail, the nail of your thumb, because of its small size.
What size is a YouTube thumbnail?
YouTube recommends 3840 × 2160 pixels in 16:9 format, with a minimum width of 640 pixels, in JPG or PNG.
What software can you use to make a thumbnail?
You can use free tools like Canva or Adobe Express, which have templates, or more advanced programs like Photoshop.
Can you put a video in an email?
Most email clients don’t play video. The usual approach is to add a video thumbnail with a play button that links to the page where the video can be watched.