What Is Alt Text and How to Write It Free?

What Is Alt Text? The Simple Definition

Alt text, short for alternative text, is the text inside the alt attribute of an HTML image tag. It looks like this in code: <img src="roof.jpg" alt="Roofer replacing asphalt shingles on a two story house">. People do not see it on the page. Screen readers, search engines and broken image placeholders do.

You may also hear it called alt tag, alt attribute or alt description. They all mean the same thing. Technically it is an attribute, not a tag, but alt tag is the name most people search for.

<img src="kitchen-remodel-austin.webp" alt="Finished white kitchen remodel with quartz island in an Austin home">

What Is the Purpose of Alt Text? 3 Fast Reasons It Matters

Alt text has three jobs: it makes images accessible, it helps search engines understand them, and it fills the gap when an image fails to load.

Accessibility

People who use screen readers hear the alt text instead of seeing the picture. Without it, the screen reader may read the file name, like IMG 4471 jpg, which tells them nothing. The W3C treats text alternatives as a basic accessibility requirement in WCAG.

Search engines

Google says in its image SEO guidance that it uses alt text, along with computer vision and the page content, to understand what an image is about. That helps the image show up in Google Images and gives the page more context.

Broken images

If an image is blocked or slow, the browser shows the alt text in the empty box. The visitor still knows what should be there.

What Is Alt Text in SEO and How Does It Help Rankings?

In SEO, alt text is one of the clearest signals you can give Google about an image. It helps the image rank in Google Images and adds relevant words to the page. It is not a magic ranking lever on its own, but missing alt text is a wasted chance on every image.

For local businesses this matters more than most people think. Job photos are proof of real work in real places. A photo of a finished deck in Plano with alt text that says so connects the image, the service and the city in one line.

How to Write Image Alt Text for SEO: Best Free Method

Describe what is in the image in one plain sentence, put the most important detail first, and add the service or location only when the picture really shows it. That is the whole method. Everything else is detail.

1. Start with the subject: who or what is in the photo.
2. Add the action or state: installing, finished, before, after.
3. Add one detail that makes it specific: material, color, room, street type.
4. Add the service or city if it fits naturally and is true.
5. Read it out loud. If it sounds like a robot wrote it, rewrite it.

Do not start with "image of" or "picture of". Screen readers already announce that it is an image. Do not repeat the same keyword on every photo either. Ten images that all say "best plumber Dallas" help nobody.

What Is an Example of Alt Text? Good vs Bad Examples

A good alt text example is "Technician cleaning a dryer vent on the exterior wall of a brick home". A bad one is "dryer vent cleaning dryer vent cleaner near me best dryer vent". The first describes the photo. The second is keyword stuffing.

Notice the pattern. Each good example tells you what you would see if you looked at the photo. That is the test.

How Long Should Alt Text Be? Best Length for SEO

Keep most alt text under about 125 characters. There is no official limit from Google, but many screen readers handle short descriptions best, and one sentence is usually enough to describe a photo.

If an image needs a long explanation, like a chart or an infographic, write a short alt text and put the full explanation in the page text near the image. Everyone benefits from that, not only screen reader users.

Can People See My Alt Text? And Which Images Skip It?

Normal visitors do not see alt text unless the image fails to load. Screen reader users hear it, and anyone can see it in the page source. So write it as if a customer will read it, because some will.

Decorative images, like background shapes, dividers and icons next to text that already says the same thing, should have an empty alt attribute: alt="". That tells screen readers to skip them. Leaving the alt attribute out completely is different and worse, because some screen readers then read the file name.

How Do You Make Alt Text for Hundreds of Images Fast?

Use a template based bulk generator for the first draft, then edit the photos that matter most. Writing alt text by hand for 300 job photos takes hours. A template does the repeat work and you add the human detail.

The LocalSEOFlow Alt Text Generator builds alt text from templates, not AI guesses. You paste up to 500 file names, and it fills in your business details and service. If a file name ends with a city and a two letter US state code, like deck-repair-plano-tx.jpg, it picks up the city for you. When you are done, export everything as a CSV.

After the export, open your ten most important images, like the home page hero and your top service page photos, and add one specific detail to each by hand. Templates get you to good. Your eyes get you to great.

Common Alt Text Mistakes to Fix Fast

• Keyword stuffing. Repeating a phrase on every image looks spammy and helps nobody.
• Empty alt on real content. Job photos and product photos need a description.
• File names as alt text. IMG 4471 tells a screen reader user nothing.
• Describing what is not there. Do not add a city the photo was not taken in.
• Same alt text on every image. Each photo shows something different, so say what.

If you want to check which images on a page are missing alt text, our image SEO pipeline prepares the file side, and a page crawl in any SEO tool lists missing alt attributes.

Frequently asked questions