Customer-led SEO
Visual Content & Accessibility

Your Quick Reference Guide for Image SEO

Tamara Hellgren
Feb 3, 2023
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Get practical, data-backed tips for optimizing images for SEO, including image sizes, ratios, formats, and more. All the info, none of the ultimate guide BS.

Key Points

  • Why optimize images for SEO? Optimized images can improve page rankings, load speed, and accessibility, attracting more visitors.
  • Best image formats for SEO: Use WebP for speed and compression. Use PNG for lossless quality and transparency. Use JPG for compatibility.
  • Ideal image sizes and ratios:
    • Open Graph: 1200px × 628px (1:1.9.1), 1600px x 900px (16:9), 1200px x 675px (16:9), 1200px x 1200px (1:1), 1200px x 900px (4:3)
    • Google Discover and News: 1200px x 675px (16:9), 1200px x900px (4:3), 1200px x 1200px (1:1) - All images in content should be at least 1200px wide!
    • Blog hero images: 1600px x 900px (16:9), 1200px x 675px (16:9), 1200px x 1200px (1:1), 1200px x 900px (4:3) - Just don't go smaller than 1200px - larger is totally fine.
  • Important image SEO practices:
    • Compress images before uploading to reduce file size and improve page load speed.
    • Use descriptive, relevant alt text to help search engines understand the image content and to aid accessibility.
    • Avoid using text in images as screen readers cannot interpret text within images. Yes, AI, but don't rely on GenAI tools for accessibility.
    • Optimize filenames with context to improve search engine visibility.
  • Why unique images? Google and users prefer unique images over stock images.

Current Search Engine Limitations

Your audience values unique images more than those found on multiple sites. Avoid using stock imagery for featured images when possible; it's less critical for background images. Your audience will appreciate this too.

Optimize images before uploading them. Familiarize yourself with Google's image publishing guidelines. Quality, original, optimized images can improve your web pages' rankings and attract more people via Google Image Search.

Best Image Formats for SEO

WebP is the best format for speed and compression, but users prefer JPG or PNG for compatibility. Our data suggests WebP images are less likely to be indexed in image search than JPGs and PNGs.

Choosing the optimal format for your images enhances quality on all screen sizes and can improve page speed.

  • PNG (.png) is better than JPEG (.jpg) for websites because it uses lossless compression, maintaining quality.
  • WebP (.webp) is even better for speed and compression, though it performs worse in image search. Developed by Google, WebP offers smaller file sizes and better compression without quality loss. It supports transparency, unlike JPEG.
  • Compatibility: WebP is supported by most modern browsers, including Chrome, Firefox, Microsoft Edge, and Safari. Note that older Safari versions do not support WebP images.

WebP images used in Open Graph images (<code>og:image</code>) do not work on LinkedIn posts.

Many tools can convert JPEG or PNG files to WebP, like TinyIMG. Adobe and Webflow have built-in WebP converters.

eCommerce & Google Merchant Center Product Images

  • Product images should be 1x1 ratio (square) to ensure uniformity and visual appeal.
  • The product should occupy 75%-90% of the image frame to highlight the product clearly.
  • Use white or transparent backgrounds to keep the focus on the product.
  • Optimize resolution & resize images before uploading to ensure fast loading times and clear display.
  • Use image alt tags to list product name, type, and important attributes (like color) to improve search engine ranking.
  • Test product-only & lifestyle shots to see which performs better for your audience.
  • Prefer unique pictures over manufacturer-provided or stock photos to increase engagement and improve SEO.
  • Use multiple images in crawlable & indexable carousels to give users multiple views and increase time on page.
  • Product images on PDPs should be above the fold on desktop & mobile to ensure immediate visibility.
  • Mix product images with video, if possible, to provide a richer user experience.
  • Avoid using the same product image on multiple PDPs to ensure each page has unique content.

Image Sizing & SEO

Compress images before uploading them to the CMS to avoid slowing down page loading speed and annoying users.

Don't rely on CSS or HTML attributes to size down (or up) an image. The best size depends on its use: background, hero, banner, blog image, etc. Check the image size guidelines for your CMS, like the WordPress image size guide.

There's no specific size requirement for Google search results, but the image must be indexable and publicly accessible.

For specific elements, page types, and SEO goals:

Cheatsheet: Best Image Sizes for SEO in Pixels (and Aspect Ratio)

Open Graph Protocol

  • 1600 x 900 (16:9)
  • 1200 x 675 (16:9)
  • 1200 x 1200 (1:1)
  • 1200 x 900 (4:3)

Google Discover

  • 1200 x 675 (16:9)
  • 1200 x 900 (4:3)
  • 1200 x 1200 (1:1)

Google News

  • 1200 x 675 (16:9)
  • 1200 x 900 (4:3)
  • 1200 x 1200 (1:1)

Blog or Article Hero Images

  • 1600 x 900 (16:9)
  • 1200 x 675 (16:9)
  • 1200 x 1200 (1:1)
  • 1200 x 900 (4:3)

Infographic Image Sizing

  • 600 x 2400 (1:4)

Google Business Profile Image Sizes

  • Google Business posts: 1200 x 900 (4:3)
  • Google Business logo: 720 x 720 (1:1)
  • Other Google Business photos: 1200 x 900 (4:3), 1200 x 1200 (1:1), 1200 x 675 (16:9)

Product Images on eCommerce Websites

  • At least 1500 x 1500 (1:1) with the product occupying 75%-90% of the frame

Product Images for Google Merchant Center (Google Shopping)

  • At least 1500 x 1500 (1:1)

Optimizing Image Filenames for SEO

Optimize image filenames before uploading. Once Google crawls your images, it won't re-crawl them for a while, so there's no point in changing existing filenames. Follow these best practices:

  • Include a target keyword in the filename to improve search engine visibility.
  • Keep filenames short with keywords at the beginning to make them easily identifiable.
  • Use descriptive and relevant words to help with search engine indexing.
  • Use lowercase letters to maintain consistency and avoid errors.
  • Use dashes instead of spaces or underscores to separate words for better readability.
  • Translate filenames if publishing in multiple languages to reach a broader audience.

Example: karrie-lane-headshot.jpg

Alternative (Alt) Text for Images

Alt text serves multiple purposes:

  • Describes the image for search engines, aiding in image indexing.
  • Appears if the image fails to load, providing context to users.
  • Read aloud by screen readers, making content accessible to visually impaired users.

Alt text helps search engines understand the image content. Keep it short and to the point. Google considers alt text the most important image attribute.

Best practices:

  • Be descriptive and relevant to help search engines and users.
  • Avoid "picture of" or "photo of" as they add unnecessary words.
  • Use keywords naturally to enhance SEO without keyword stuffing.
  • Keep it concise to ensure clarity and relevance.
  • Use specific language (e.g., "Honda Civic" instead of "car") to provide detailed information.
  • Include context based on the page topic to improve user experience.
  • For icons, convey what the icon symbolizes (e.g., "Visit LinkedIn page") to provide clear guidance.

Example: Karrie Lane's 2023 professional headshot

The Problem with Using Text in Images

Avoid using text in images. It doesn't meet accessibility guidelines as screen readers can't read it. If you must use text in images, repeat the text verbatim in the alt tag to ensure accessibility.

Google can now extract text from images using Google Cloud Vision API or Google Keep, but this technology is not perfect. Relying on it can lead to misinterpretation or missed information.

Do Image Captions Help SEO?

Image captions provide more context for images on a page. They don't directly affect SEO but improve UX and engagement. Captions help visitors understand images and keep them engaged, which can indirectly improve SEO by reducing bounce rates and increasing time on site.

Best practices:

  • Add captions if necessary or helpful to provide additional context.
  • Avoid repeating alt tag text in captions to keep content unique.
  • Capitalize the first word and proper nouns for readability.
  • No need for complete sentences or periods, keeping captions concise and clear.

Image Title Tags: Not the Same as Alt Tags

Title tags appear when you hover over an image or link. They are not required, don't affect search rankings, and are not seen by mobile users.

If you use title attributes, make sure the text is supplemental since most visitors won't see it, and it's inaccessible to mobile users and screen readers.