When it comes to image optimization for SEO, a common question pops up:
“If I name my images well, do I really need to bother with alt tags?”
The short answer?
Yes—you absolutely do.
Image file names and alt text serve different purposes in helping search engines (and users) understand your visuals. They work together, but one doesn’t replace the other. If you’re skipping alt tags because you’ve renamed your image files to be keyword-friendly, you’re leaving both SEO power and accessibility behind.
Let’s break down what each does—and why you need both.
What Is an Image File Name?
An image file name is the actual name of your image file as it’s uploaded—e.g., seo-checklist-one-page-site.png.
A Good File Name Should:
- Be descriptive of the image
- Use keywords naturally
- Be in lowercase, with hyphens instead of spaces
- Avoid generic names like image1.jpg or screenshot.png
Google does scan image filenames to get clues about content, especially in image search indexing. But this is just step one.
What Is Alt Text (Alt Tag)?
Alt text (or “alternative text”) is an attribute you assign to an image in your HTML or CMS that describes the image’s content for:
- Screen readers (accessibility)
- Search engines (relevance context)
- Fallback messaging (when the image doesn’t load)
Example:
img src="seo-checklist-one-page-site.png" alt="Checklist of SEO tips for one-page websites including headings, anchor links, and load speed."
Why It’s Powerful:
- Helps visually impaired users
- Enhances content relevance for search engines
- Increases likelihood of appearing in Google Images
- Improves overall on-page SEO
How File Names and Alt Tags Work Together
Think of your image file name and alt text as a duo:
| Element | Purpose | Visible to Users? |
|---|---|---|
| File Name | Helps search engines identify the image topic | No |
| Alt Text | Describes image for screen readers & SEO | Sometimes |
Google uses both to better contextualize your page content and improve your rankings—especially in visual search.
If you use only one, you’re leaving important signals behind. Worse, skipping alt tags can hurt your site’s accessibility compliance and user experience.
Common Mistakes to Avoid
- Using underscores or spaces in file names instead of hyphens
- Stuffing keywords unnaturally into alt tags
- Leaving alt text blank unless the image is purely decorative
- Copy-pasting the same alt text across all images
Best Practices for SEO-Optimized Images
| Task | Recommendation |
|---|---|
| File Name | Use lowercase, hyphenated, keyword-rich names like responsive-website-design-example.jpg |
| Alt Text | Write brief, clear descriptions with keywords, e.g., “Illustration of mobile-friendly website layout” |
| Compress Images | Use tools to reduce file size without losing quality |
| Use Descriptive Captions (Optional) | Helps if images convey complex or data-heavy info |
| Add Structured Data (Where Relevant) | For product, recipe, or news images, use schema markup |
Final Thoughts
If you’re investing time into creating or sourcing quality images for your site, don’t let that effort go to waste with weak SEO.
A good file name gives your image context.
A good alt tag makes it valuable.
Together, they make your content stronger.
Whether you’re building a lean one-page site or a full-blown multi-page platform, optimizing every image properly can help boost rankings, user experience, and accessibility all in one go.