What Size Should Blog Images Be?
There is a simple spec for blog images: a width, a file size, and a format. Get those three right and your posts stay sharp and fast. This guide gives the exact numbers, explains why each one matters, and shows the one-step way to hit all three before you upload.
Table of Contents
The short answer
A blog image has three numbers worth getting right: how wide it is, how heavy the file is, and what format it is in. For the images that sit inside a post, the spec is simple:
- Width: 1200 to 1600 pixels wide.
- File size: under 150 to 200 KB each.
- Format: WebP, with JPG as a fallback.
For a featured or hero image, which is shown larger, go 1600 to 2000 pixels wide and keep it to roughly 200 to 300 KB. The rest of this guide explains why each number is what it is, so you can adjust for your own theme.
Width: how many pixels wide
The trick is to match the image width to the space it actually fills, then account for high-resolution screens. Most blog themes have a content column of 700 to 800 pixels. A retina display packs roughly twice the pixels into that space, so to look crisp the image needs to be about double the column width: 1200 to 1600 pixels. Anything beyond that is wasted, because the browser just scales it down to fit the column while still downloading every extra pixel. That is why a 4000-pixel phone photo is not sharper on your blog, only slower.
File size: how many KB
Width is about sharpness, file size is about speed, and they are separate. Even at the right pixel width, an uncompressed image can be large. Target under 150 to 200 KB for in-body images and around 100 KB for thumbnails. The reason matters for more than feel: Google uses page speed as a ranking factor through Core Web Vitals, and images are usually the heaviest thing on a page. One oversized hero image is the single most common cause of a slow post. For the deeper performance angle, see our guide on optimizing images for Core Web Vitals.
Format: WebP first
For photographs on a blog, WebP is the default in 2026. It is 25 to 35 percent smaller than JPG at the same visual quality, and every current browser supports it, so the old reason to avoid it is gone. Keep JPG only as a fallback for ancient software, and reserve PNG for graphics with text, logos, or transparency, never for photos, where it balloons the file. If you are weighing the options, our best image format for the web guide breaks down each one.
Hitting all three in one step
Doing this by hand means three tools: one to resize, one to compress, one to convert to WebP. That is the job BlogDrop collapses into one. You drop a full-resolution photo in, and it comes out resized to a sensible blog width, compressed to a light file size, and converted to WebP, ready to upload. It is the fastest way to meet the whole spec above without thinking about it for every image.
Right width, weight, and format in one drop
BlogDrop resizes, compresses, and converts to WebP in a single step. Free, in your browser.
Open BlogDrop, FreeThe mistakes that slow blogs down
Three mistakes account for most slow blogs. The first is uploading the raw photo, a 4000-pixel, 4 MB file straight off a phone. The second is trusting the CMS to handle it: WordPress makes smaller display versions but keeps your huge original and often still serves oversized files, so resizing first is the only guarantee. The third is skipping the filename and alt text: a descriptive filename and alt attribute help both accessibility and image search, and cost nothing to add while you are preparing the image. For the full WordPress-specific routine, see how to optimize images for WordPress.
FAQ
What size should blog images be?
For most blogs, make in-body images 1200 to 1600 pixels wide, keep each file under about 150 to 200 KB, and serve them as WebP with a JPG fallback. That is wide enough to look sharp on modern screens while staying small enough to load fast.
What is the best width in pixels for a blog image?
Match it to your theme's content width, which is usually 700 to 800 pixels, then double it for retina screens, so 1200 to 1600 pixels wide is the sweet spot. Going much larger just adds weight no visitor will ever see, because the browser scales it down anyway.
How small should a blog image file be?
Aim for under 150 to 200 KB per in-body image, and under about 100 KB for thumbnails. A single image over 1 MB, which is what a raw phone photo often is, is the most common reason a blog post feels slow.
What is the best format for blog images?
WebP. It is 25 to 35 percent smaller than JPG at the same quality and every modern browser supports it. Use JPG only as a fallback for very old software. Use PNG just for graphics with text or transparency, not for photos.
What size should a blog featured image be?
A featured or hero image is usually shown wider, so 1600 to 2000 pixels wide is reasonable, but keep it compressed to roughly 200 to 300 KB. It is also the image used in social previews, so a 1.91 to 1 ratio, around 1200 by 630, works well for sharing cards.
Do I need to resize before uploading, or will the CMS do it?
Resize first. A CMS like WordPress generates display sizes, but it keeps your giant original and often still serves oversized files. Uploading an already correctly sized, compressed image is the only way to be sure the page stays light.
