Similar to how a package image in retail can encourage a purchase, a thumbnail on the internet creates the first im­pres­sion of images, videos, or other web content. A well-crafted thumbnail image sparks curiosity and leads to more clicks.

What is a thumbnail?

A thumbnail is a smaller preview image designed to give a quick visual im­pres­sion of the content, whether it’s a video, image, or article. Thumbnail images are commonly used across the internet, including in online stores, where they help display multiple products in an organized way. Clicking on the thumbnail directs you to the original file or product page.

The biggest advantage of thumb­nails is the reduced file size. When a large number of image or video contents are initially loaded as small preview images, it no­tice­ably improves the website’s loading time. Users can then decide which content they want to view in full size. Ad­di­tion­al ad­van­tages include:

  • Space-saving: Thumb­nails provide a quick overview of many contents in a small area.
  • User-friend­li­ness: The brain processes images faster than text, so thumbnail images support intuitive nav­i­ga­tion.
  • In­ter­ac­tiv­i­ty: At­trac­tive preview images encourage users to click on content (click-through rate) and interact with the page.
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Where are thumb­nails used?

Thumbnail images can be found all over the web—such as on YouTube, in Google Image Search, in social media feeds, or in online stores. However, their design and style vary sig­nif­i­cant­ly depending on the platform and purpose. While they primarily serve as neutral product images on Amazon, YouTube thumb­nails often resemble small “bill­boards” that visually tease the content and capture attention.

YouTube thumb­nails

With the intense com­pe­ti­tion on YouTube, it’s essential for the thumbnail to capture attention within seconds to improve key KPIs like the click-through rate (CTR). Many creators on the platform use emotional facial ex­pres­sions, graphic elements like arrows or circles, and strong contrasts to make their thumb­nails stand out from the crowd. Con­sis­tent branding is also key, achieved through uniform colors, a recurring layout, or featuring the same people.

Image: Thumbnails of the Humano Studios YouTube channel
The Humano Studios account, which regularly uploads DJ sessions of various artists, features each artist at the mixing desk on every thumbnail, with the genre in bold letters and vibrant colors in the back­ground. Source: https://www.youtube.com/@Hu­manoS­tu­dios

To display a large number of results to users si­mul­ta­ne­ous­ly, Google uses thumb­nails in its image search instead of high-res­o­lu­tion original images. These are linked preview images that belong to websites. If YouTube videos are also listed in the search results, Google uses the cor­re­spond­ing video thumbnail as a preview. Thumbnail images also play a central role in “Google Discover” for the click prob­a­bil­i­ty of an article.

Image: Image selection in Google’s Image Search
Example of thumb­nails in Google Image Search. Source: https://www.google.com/

Thumb­nails in online shopping

In online stores, preview images often display a neutral view of the product against a white back­ground (cutout), without elaborate staging. In fashion stores, models often appear in a neutral pose on thumb­nails; aes­thet­i­cal­ly pleasing per­spec­tives and detail shots are shown only on the product detail page.

Many stores now au­to­mat­i­cal­ly provide more in­ter­ac­tiv­i­ty through modern shop systems. For example, when you hover over the thumbnail (mouseover), you can often browse through ad­di­tion­al views or display al­ter­na­tive colors without leaving the page. This makes product research sig­nif­i­cant­ly faster and more user-friendly.

Image: Thumbnails of the Sears online store
For the products, different colors can be selected in­ter­ac­tive­ly directly below the image. Source: https://www.sears.com/clothing-women-s-clothing-women-s-blazers-jackets-vests/b-5007121?viewAll=true
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Common sizes for thumb­nails

Depending on the website, the purpose and therefore the optimal size of thumbnail images can vary. Here are common guide­lines (as of 2025):

  • Google Search / Discover: Google rec­om­mends images that are at least 1,200 pixels wide for optimal display in Discover and Search. While smaller images (starting at 300 pixels) do work, larger images are often displayed more at­trac­tive­ly (e.g., as a large card format).
  • Amazon: Amazon requires a minimum width of 500 pixels on the longest side. However, it is rec­om­mend­ed to use 1,000 to 1,600 pixels on the longest side. This size activates the “zoom feature” on the product page, which is crucial for con­ver­sions.
  • YouTube: Thumb­nails on YouTube are displayed in a 16:9 format. The optimal size is 1,280 x 720 pixels (minimum width 640 pixels). File sizes should ideally remain under 2 MB.
  • Pinterest: Pinterest is a vertical search engine. Ideal images have a 2:3 aspect ratio, such as 1,000 x 1,500 pixels. Deviating formats are often cropped or less favored in the feed.

In the USA, thumb­nails of copy­right­ed images are governed by the Copyright Act’s fair use doctrine. Courts apply a four-factor test—con­sid­er­ing the trans­for­ma­tive purpose (like search indexing), the original work’s nature, the portion used, and market impact—often ruling thumb­nails fair use in cases such as Kelly v. Arriba Soft (2003) and Perfect 10 v. Amazon. To stay safe on blogs or websites, pri­or­i­tize using self-created images, public domain content, or Creative Commons content with proper at­tri­bu­tion, embedding via links rather than hosting copies, and licensed stock photos. Avoid non-trans­for­ma­tive dec­o­ra­tive uses that could lead to potential in­fringe­ment claims.

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