Images contribute significantly to search engine optimisation — from Google Image Search traffic to page speed scores and user experience signals. Here is the complete guide to image SEO for bloggers in 2025.
Image SEO Ranking Factors
- File name — contains keywords relevant to the image content
- Alt text — describes the image accurately with relevant keywords
- Image size and dimensions — correctly sized for display context
- File format — modern formats (WebP) preferred by Google
- Page load speed — compressed images improve Core Web Vitals
- Structured data — Image schema markup helps rich results
File Naming Best Practices
- Use descriptive, keyword-rich file names: "golden-retriever-puppy.jpg" not "IMG_4521.jpg"
- Use hyphens between words, not underscores or spaces
- Keep names under 60 characters
- Include your target keyword where it naturally fits
Alt Text Best Practices
- Describe what the image shows — as if explaining it to a blind person
- Include your target keyword naturally, once
- Keep under 125 characters
- Do not start with "Image of..." or "Photo of..." — Google already knows it is an image
- Leave alt="" for purely decorative images
Image Size and Speed for SEO
Google's Core Web Vitals include Largest Contentful Paint (LCP) — often an image. Compress and resize all blog images to under 200KB wherever possible. Convert to WebP for the best balance of quality and speed. Use imgresizr.com to compress and convert all blog images before uploading to WordPress, Ghost, or your blogging platform.
Optimise your blog images for SEO using imgresizr.com — proper size, right format, and fast loading for better Google rankings.