What alt text does and why it matters

Alt text is a short written description of an image that appears when the image does not load, and that screen readers read aloud to people who cannot see the picture. It lets someone using a screen reader know what the image shows — whether it is a chart, a photo of a person, a button, or a decorative element. Without alt text, a screen reader user hears nothing, or just hears the filename, which is usually meaningless.

Adding alt text takes less than a minute per image and works the same way across most programs: you right-click the image, find the alt text field, and type a description. The exact steps change depending on whether you are using Windows, Mac, a web browser, or a phone, but the principle is identical. This guide covers the most common places you will encounter images and need to add descriptions.

Key Takeaways

  • Alt text should describe what the image shows in one or two sentences, not repeat the caption or say "image of".
  • In Microsoft Word and Google Docs, right-click the image and select "Alt Text" or "Edit Alt Text" to open the field.
  • On websites, you cannot add alt text to images you did not upload, but you can report missing alt text to the site owner.
  • On phones, the process varies by app — some allow alt text when you upload a photo, others do not offer the feature at all.
  • Decorative images that add no information should have empty alt text so screen readers skip them.

Adding alt text in Microsoft Word and PowerPoint

Open the document and right-click the image. Select Alt Text from the menu. A panel opens on the right side of the screen with a text field. Type your description — aim for one or two sentences that explain what someone would see if they looked at the image. Do not start with "image of" or "picture of"; just describe the content directly.

If the image is purely decorative — a border, a background element, or a divider with no information — leave the alt text field empty. This tells the screen reader to skip it entirely, which is better than reading a description of something that does not matter to the document.

In PowerPoint, the process is identical. Right-click the image, select Alt Text, and type your description in the panel that appears. If you are embedding a chart or graph, describe what the chart shows and what the key takeaway is, not every data point.

Adding alt text in Google Docs and Google Sheets

Right-click the image and select Alt Text from the menu. A dialog box opens with two fields: one for a title and one for a description. The title field is optional; the description is what screen readers will read. Type a one- or two-sentence description of what the image shows.

In Google Sheets, the process is the same. Right-click the image, select Alt Text, and fill in the description field. If the image is decorative, you can leave the description blank, and the screen reader will skip it.

Adding alt text on websites and social media

If you are uploading an image to a website you manage — a blog, a business site, or a content management system — look for an Alt Text field or Image Description field when you upload. The location varies by platform. On WordPress, it appears in the Image Details panel. On Squarespace, it is in the Image Settings. On Wix, it is under Image Properties. If you do not see the field when ready, search the platform's help documentation for "alt text" or "image description".

On social media platforms like Facebook, Instagram, Twitter, and LinkedIn, you can add alt text when you upload a photo. On Facebook, click the image after uploading and select Edit Alt Text. On Instagram, tap the image, then Advanced Settings, then Alt Text. On Twitter, click the image icon when composing a tweet, upload your image, then click Add Description. On LinkedIn, upload the image, then click the three dots and select Edit Alt Text.

If you encounter an image on a website that has no alt text and you are not the owner, you cannot add it yourself. Instead, contact the site owner or administrator and let them know the image is missing a description. Many sites have a contact form or feedback option.

Adding alt text on iPhone and Android phones

On iPhone, open the Photos app, select the image, tap Edit, then tap the three dots menu and select Info. Scroll down to Description and type your alt text there. This description is stored with the photo and will be read by screen readers if the image is shared or uploaded elsewhere.

On Android, the process depends on your phone model and version. Open the Photos app (Google Photos, Samsung Gallery, or your default app), select the image, tap the three dots menu, and look for Edit or Details. Some Android phones have a Description field; others do not. If your phone does not offer this feature, you can add a description when you upload the image to a website or app that supports alt text.

When uploading photos to messaging apps like WhatsApp, Telegram, or Signal, most do not offer alt text fields. If accessibility is important for your audience, consider uploading images to a website or document instead, where you can add descriptions.

Writing effective alt text

Good alt text is specific and concise. Instead of "photo," describe what is in the photo: "A golden retriever sitting on a blue couch" is better than "dog." Instead of "chart," describe what the chart shows: "A bar chart comparing sales by quarter, showing Q3 as the highest at 45,000 units" is better than "sales chart."

Keep descriptions to one or two sentences. Screen readers read alt text aloud, so long paragraphs become tedious. If the image needs a longer explanation, put that explanation in the caption or in the text around the image, and use alt text for the quick version.

Do not repeat the caption. If the caption already says "Sales by quarter," your alt text should add detail, not repeat it. For example: alt text could be "Bar chart showing Q3 with the highest sales at 45,000 units, followed by Q2 at 38,000 and Q1 at 32,000."

For decorative images — borders, spacers, or purely visual elements that do not convey information — leave alt text empty. This is better than writing "decorative image" because it tells the screen reader to skip the element entirely.

Checking that alt text is working

To verify that your alt text is actually being read, you can test it yourself. On Windows, open Narrator (press Windows key + Control + N). On Mac, open VoiceOver (press Command + F5). Navigate to your image using the arrow keys or Tab key, and listen to what the screen reader says. If it reads your alt text, you have done it correctly. If it reads the filename or says nothing, go back and add or fix the alt text.

In a web browser, you can also right-click an image and select Inspect (or Inspect Element) to see the HTML code. Look for the alt attribute. If it is empty or missing, the image has no alt text. If it contains your description, the alt text is in place.

Frequently Asked Questions

How long should alt text be?

One or two sentences is ideal. Aim for 125 words or fewer. Screen readers read alt text aloud, so keep it brief enough that someone listening does not lose patience. If the image needs a longer explanation, put that in the surrounding text or caption instead.

Should I include the word "image" in alt text?

No. Screen readers already announce that it is an image. Just describe what the image shows. Instead of "Image of a sunset over the ocean," write "A sunset over the ocean with orange and pink clouds reflecting on the water."

What if the image is a screenshot of text?

Describe what the screenshot shows, or include the text itself if it is short. For example: "A screenshot of an email from HR confirming the meeting is rescheduled to Tuesday at 2 p.m." If the text is long, describe the content and put the full text in the document itself so it can be copied and searched.

Can I use the same alt text for multiple images?

Only if the images are truly identical. If you have five photos of the same product from different angles, each one should have slightly different alt text describing the angle or what is visible in that particular shot. If you have the same logo appearing five times in a document, one instance can have alt text and the others can be empty.

What if I do not know how to describe an image well?

Describe what you see as if you were telling someone over the phone who cannot see the screen. Include the main subject, important details, colors if they matter, and the context. If it is a chart or graph, describe the trend or key finding, not every data point. If you are unsure, ask someone else to look at the image and tell you what they notice first.