Image SEO: Alt Text and File Names That Help You Rank

Here’s something most small business websites get completely wrong: their images. Not the pretty pictures themselves — those are usually fine. It’s the invisible stuff around them. The file named IMG_4829-final-FINAL2.jpg. The alt text field left blank on every single photo. Google can’t see your images the way you do, and when you give it nothing to work with, you’re leaving search traffic on the table. Nailing your image SEO alt text is the fastest fix.

Getting image SEO alt text right is one of the highest-ROI fixes in all of SEO. It takes minutes per page, costs nothing, and opens up an entire traffic channel — Google Images — that most of your competitors are ignoring. Let me show you exactly how to do it.

Image SEO Alt Text: What It Actually Is (and Why Google Cares)

Alt text — short for “alternative text” — is the written description attached to an image in your page’s HTML. It was originally designed for accessibility: screen readers read it aloud so visually impaired visitors know what’s in the picture. That’s reason enough to write it.

But here’s the SEO angle: Google’s crawlers are essentially blind. They can’t “look” at your photo of a handmade oak dining table and know what it is. The alt text, the file name, and the surrounding content are how Google figures it out. Good alt text helps your images rank in Google Images (which drives real buying traffic — people searching images are often close to purchasing), and it gives the page itself a small but real relevance boost for its topic.

Google’s own image SEO documentation spells this out: descriptive file names and alt text help Google understand your images. This isn’t a trick or a hack — it’s literally what Google asks you to do.

How to Write Image SEO Alt Text That Ranks (With Real Examples)

Most alt text I audit falls into two traps: it’s either empty, or it’s keyword-stuffed garbage like “plumber Leeds emergency plumber cheap plumber best plumbers Leeds”. Both are useless. Here’s the formula that works:

Describe the image specifically, in under 125 characters, as if explaining it to someone on the phone. Then, where it fits naturally, include your target keyword once.

Real examples from small business sites:

A bakery in Manchester. Bad: “cake” or “” (empty). Good: “Three-tier chocolate wedding cake with fresh raspberries on a white stand”. Better (with keyword): “Three-tier chocolate wedding cake with fresh raspberries — handmade by our Manchester bakery”.

A plumber’s van photo. Bad: “IMG_2210.jpg”. Good: “Branded plumbing van parked outside a semi-detached house in Leeds”.

A product shot for an online shop. Bad: “product1”. Good: “Hand-poured soy candle in amber glass jar with wooden lid”.

Notice the pattern? Specific, visual, honest. Moz’s image optimization guide makes the same point: write for humans first, and the SEO benefit follows. If a keyword fits naturally, include it. If it doesn’t, don’t force it — a clear description beats a stuffed one every time.

File Names Matter More Than You Think

Before an image even gets alt text, it has a file name — and IMG_4829.jpg tells Google nothing. Rename your files before uploading, using lowercase words separated by hyphens:

chocolate-wedding-cake-manchester-bakery.jpg beats IMG_4829-final-FINAL2.jpg every single time. It takes ten seconds, and unlike alt text, you can’t easily fix it after upload without re-uploading (WordPress keeps the original file name). Make it a habit: rename first, upload second.

Two more quick file rules. Compress your images — a 4MB photo slows your page to a crawl, and page speed is a ranking factor. Free tools like TinyPNG or WordPress plugins like Smush shrink files by 60–80% with no visible quality loss. And use modern formats: WebP beats JPEG and PNG on file size for the same quality, and every modern browser supports it.

The Image SEO Checklist: 7 Things to Fix on Every Page

Want the quick version? Run through this on your most important pages:

1. Every meaningful image gets alt text. Decorative images (dividers, background flourishes) can stay empty — that’s actually correct. But every photo, product shot, team picture and infographic needs a real description.

2. File names are descriptive. Lowercase, hyphenated, keyword-aware. Rename before uploading.

3. Images are compressed. Aim for under 200KB per image wherever possible. Your pages will load faster and visitors will thank you.

4. Dimensions match the display size. Don’t upload a 4000-pixel-wide photo to display at 800 pixels. Resize it first — browsers download the whole file regardless.

5. One image per page targets Google Images. Your most important image should have your page’s primary keyword in its alt text and file name. That’s your Google Images contender.

6. Captions where they help humans. Captions (the visible text under images) get read 300% more than body copy, according to classic readability research. They’re not a direct ranking factor, but engaged visitors are a ranking signal.

7. No text baked into images. Infographics with all the information trapped inside a PNG are invisible to Google. Put the key points in real HTML text near the image too — and never use images instead of headings, which is a header tag mistake I see constantly.

Common Image SEO Mistakes That Hurt Rankings

A few more traps worth knowing. Hotlinking — embedding images hosted on someone else’s server — means you get zero SEO credit and the image can vanish any time. Always host your own images.

Missing width and height attributes cause layout shift (content jumping around as images load), which hurts your Core Web Vitals scores. WordPress adds these automatically these days, but page builders sometimes don’t.

Giant hero sliders with five uncompressed 3MB images are the classic small-business site killer. One optimized hero image beats a five-slide carousel in every test I’ve ever run — for speed, for conversions, and for SEO.

And please — don’t steal images from Google Images for your own site. Beyond the copyright risk, duplicate images across thousands of sites carry no SEO value. Original photos of your actual business, team and products outperform stock photos for trust and for image search. If you must use stock, at least rename the files and write original alt text. Our technical SEO guide covers more of these invisible issues.

FAQ: Quick Answers

Does alt text really help SEO?

Yes. It’s a confirmed relevance signal for image search, and it helps Google understand the page’s topic. It’s not going to single-handedly rank you #1, but across a whole site, proper alt text adds up — especially for Google Images traffic, which converts well for product and local businesses.

How long should alt text be?

Keep it under 125 characters. Screen readers may cut off longer descriptions, and concise alt text forces you to be specific. One clear sentence is the sweet spot.

Should I put keywords in every image’s alt text?

No — that’s keyword stuffing and it can backfire. Use your primary keyword in the alt text of one or two key images per page, and write natural descriptions for the rest. Relevance beats repetition.

Do I need alt text on decorative images?

No. Purely decorative images (borders, spacers, background textures) should have empty alt text (alt=””) so screen readers skip them. Only meaningful images — photos, products, diagrams, team pictures — need descriptions.

Start With Your Money Pages

You don’t need to fix 500 images today. Start with the pages that make you money: your homepage, your top service pages, your best product pages. Rename the files, write real alt text, compress everything. An hour of work, and you’ve fixed the pages that matter most.

Then make it a habit: every new image gets a descriptive file name and proper image SEO alt text before it goes live. Future you — and Google — will be grateful.

Want a professional eye on your whole site? Our 25-point SEO audit covers images plus the other two dozen things holding small business sites back. Silver Crown Star Marketing works with businesses across the UK, USA and Europe — get in touch and let’s find your quick wins.