Image SEO for Bloggers: A Practical Checklist

Most posts about "image SEO" turn into a keyword-stuffing exercise. Google is fairly explicit about what actually matters: descriptive file names, useful alt text, fast-loading files, and images placed near the text they illustrate. Here's what to actually do, in order.

Why images are worth the extra five minutes

Two separate things are on the line every time you add an image to a post, and bloggers usually only think about one of them.

The first is discovery: Google Images and Google's visual search surfaces send real traffic, especially for recipe, DIY, product, and how-to content where people search visually before they search in text. An unoptimized image — generic file name, empty alt text, buried in a slider Google can't render — is functionally invisible to that traffic, no matter how good the photo is.

The second, and the one that actually moves your whole page's ranking, is speed. Images are the single largest asset on most blog pages, and Google's Core Web Vitals explicitly measure how fast the largest visible element (almost always a hero image) finishes loading. A bloated image doesn't just load slowly on its own — it can drag your entire post's ranking down, independent of whether anyone ever finds it through Google Images.

File names Google can actually read

Google's own guidance is blunt about this: use descriptive file names, because the file name is one of the signals it uses to understand what an image shows before it ever renders the page. IMG_4821.jpg or photo-final-v2.png tells a search engine nothing. cast-iron-skillet-seasoning-steps.jpg tells it exactly what's in the frame.

The practical rule: rename the file before upload, not after. Use lowercase words separated by hyphens (not underscores or spaces), keep it specific to the image rather than the whole page topic, and don't repeat the same file name across a dozen images that all show slightly different things — that just recreates the "IMG_4821" problem with extra steps.

Alt text: for people first, then for Google

Alt text exists primarily for accessibility — it's what a screen reader announces when someone can't see the image, and what displays if the image fails to load. Google reads it too, alongside its own computer-vision analysis of the image and the surrounding page text, to understand subject matter. Writing it well genuinely serves both audiences at once; there's no real conflict here despite how "SEO alt text" articles frame it.

Good alt text describes what's actually in the image, specifically, without turning into a keyword list. "Chocolate chip cookies cooling on a wire rack" is useful. "Chocolate chip cookies recipe easy best chocolate chip cookies" is keyword stuffing, and Google explicitly calls this out as something that can get a site treated as lower quality — the opposite of the intended effect. If an image is purely decorative (a background texture, a divider graphic), an empty alt="" is the correct choice, not a padded description; it tells assistive tech to skip it.

Format and compression: the actual tradeoff

The format war between JPG, PNG, and WebP matters less than the compression setting you ship with, but both count. Google's documentation lists JPEG, PNG, WebP, and SVG as all fully supported and indexable, so "wrong format" rarely explains a ranking problem — an oversized file usually does.

In practice: convert whatever your camera or screenshot tool spits out with the Image Converter if you need a different format, then run every image through the Image Compressor before it goes into a post. Both run entirely in your browser, so nothing uploads to a server — useful if the images aren't public yet. Dropping a 4MB phone photo to under 150KB with no visible quality loss is normal, and it's the fastest page-speed win available to anyone without touching code.

Dimensions, lazy loading, and layout shift

Two more habits matter for the "speed" half of image SEO, and both are easy to get backwards:

• Resize before upload, not after. Uploading a 4000px-wide photo and letting your theme's CSS shrink it to 800px in the browser means the visitor still downloads the full 4000px file. Resize to roughly the largest size the image will ever display at.
• Set width and height attributes (or use a theme that does), so the browser reserves the right amount of space before the image loads. Skipping this is a leading cause of layout shift — content jumping around as images pop in — which is itself one of the three Core Web Vitals metrics.
• Lazy-load images below the fold, but not the one at the very top of the post. Lazy-loading your hero image can actually delay it further, which hurts the "largest contentful paint" metric instead of helping it.

Sitemaps and structured data: worth it, but not first

For most blogs, an image sitemap and image-specific structured data are second-tier — they help Google discover images faster and can unlock richer results for recipes and products, but they don't compensate for a slow, badly-named, alt-text-free image. If your platform already generates a sitemap with images included, that's usually enough; hand-rolling structured data pays off mainly for recipe and product sites, where the markup is well-defined and the reward (recipe cards, product badges) is concrete.

A realistic pre-publish workflow

Rather than treating this as a long checklist to memorize, fold it into how you already handle images before a post goes live:

1. Take or select the photo. Crop it to roughly the size it'll display at — no need for pixel precision.
2. Rename the file to something specific and hyphenated before doing anything else.
3. If it's not already in the format you want (WebP for most photos, PNG for anything with transparency or sharp text), convert it with the Image Converter.
4. Compress it with the Image Compressor — check the preview at full size before accepting a lower quality setting.
5. Write one sentence of real alt text describing what's in the frame, not what you want to rank for.
6. Publish, and only then worry about sitemaps and structured data if the content type warrants it.

None of this takes more than a couple of minutes per image once it's a habit, and unlike a lot of SEO advice, every step here has a direct, verifiable payoff: a faster page, an accessible page, and an image Google can actually describe correctly.