How to Convert Images for WordPress: Formats, Sizes, and Optimization
WordPress powers over 40% of websites on the internet, and images are usually the heaviest assets on any WordPress page. Using the wrong format or oversized images can tank your page speed, hurt your search rankings, and frustrate visitors who abandon slow-loading sites.
The good news is that converting your images to the right format before uploading makes a massive difference. This guide walks you through exactly which formats WordPress supports, how to choose the right one for each use case, and how to convert images quickly without installing any software.
Step-by-Step Instructions
- Check your current image formats
Before converting anything, audit what you already have. Open your WordPress Media Library and look at the file extensions on your existing images. If you see a mix of PNG screenshots, HEIC photos from your phone, and random BMP files, those are prime candidates for conversion. WordPress natively supports JPG, PNG, GIF, WebP (since WordPress 5.8), and AVIF (since WordPress 6.5).
- Choose the right format for each image type
Use WebP as your default format for most images. It delivers 25-35% smaller files than JPG at the same quality and supports transparency like PNG. Use JPG for photographs where you do not need transparency. Use PNG only when you need pixel-perfect transparency, such as logos with transparent backgrounds. Avoid BMP and TIFF entirely since they are uncompressed and will slow your site.
- Convert your images with imageconvert.co
Open imageconvert.co, select your target format (WebP is recommended for WordPress), and drag your images onto the converter. You can batch convert multiple images at once. The conversion happens entirely in your browser, so your images never leave your device. Download the converted files individually or grab them all as a ZIP.
- Resize images before uploading
WordPress generates multiple thumbnail sizes automatically, but uploading a 5000x3000 pixel photo when your content area is 800 pixels wide wastes storage and processing time. Resize your images to roughly 2x your content width (around 1600 pixels wide for most themes) before uploading. This gives WordPress enough resolution for retina displays without the excess.
- Upload and verify in WordPress
Upload your converted images through the WordPress Media Library or directly in the block editor. After uploading, check your page speed using Google PageSpeed Insights. Look for the Properly size images and Serve images in next-gen formats audit results. If those pass, your images are optimized correctly.
Why WebP Is the Best Format for WordPress in 2026
WordPress added native WebP support in version 5.8, and it has quickly become the recommended format for web images. WebP files are significantly smaller than their JPG and PNG equivalents while maintaining virtually identical visual quality. For a typical WordPress blog post with 5-10 images, switching from JPG to WebP can reduce total page weight by 200-500 KB.
Google explicitly recommends WebP in its PageSpeed Insights audits. If you are seeing the Serve images in next-gen formats suggestion, converting to WebP is the fastest way to resolve it. Every major browser now supports WebP, so there are no compatibility concerns for your visitors.
WordPress Image Size Limits and Recommendations
WordPress has a default upload limit that varies by hosting provider, typically between 2 MB and 128 MB. But just because you can upload a 50 MB image does not mean you should. Large uploads slow down your admin panel, consume hosting storage, and increase server processing time as WordPress generates multiple thumbnail sizes.
- Blog post featured images: 1200x630 pixels in WebP or JPG, aim for under 100 KB
- In-content images: match your theme content width (usually 800-1200px wide), under 150 KB
- Hero/banner images: 1920x1080 pixels maximum, under 200 KB in WebP
- Thumbnails and icons: 300x300 pixels or smaller, under 30 KB
- Logo: PNG with transparency if needed, SVG if your theme supports it
Handling HEIC Photos from Your Phone
If you take blog photos with an iPhone, your images are saved as HEIC by default. WordPress does not support HEIC uploads, so you will get an error if you try to upload them directly. The fix is simple: convert HEIC to WebP or JPG before uploading. imageconvert.co handles HEIC conversion entirely in your browser using WebAssembly, so your personal photos stay private.
Frequently Asked Questions
Does WordPress automatically convert images to WebP?
WordPress 5.8 and later can generate WebP versions of uploaded images if your server supports it, but this depends on your hosting environment and PHP configuration. Many hosts do not enable this by default. Converting images to WebP before uploading guarantees the format regardless of your server setup.
Should I convert all my existing WordPress images to WebP?
If you have hundreds of existing images, batch converting them is worth the effort. Use imageconvert.co to convert them in bulk, then re-upload. The page speed improvement is immediate and can positively impact your search rankings.
What happens if a visitor's browser does not support WebP?
As of 2026, every major browser supports WebP including Chrome, Firefox, Safari, and Edge. Browser support is over 97% globally, so compatibility is not a practical concern for any modern website.
Is PNG or JPG better for WordPress product images?
For product images with solid backgrounds, JPG is usually the better choice due to smaller file sizes. If your product images need transparent backgrounds (for overlay effects or white backgrounds), use PNG. For the best of both worlds, use WebP which supports both transparency and excellent compression.
Convert images to WebP for WordPress