Rounded corners give images a softer, more modern appearance. They're standard in app design, social media graphics, blog post thumbnails, and product cards — but applying them to an actual image file (not just via CSS) typically requires Photoshop or a similar editor.
This guide explains how to round image corners using BestPNG's round corners tool, what radius values to use for different effects, and practical design applications where rounded images work best.
Why Round Image Corners?
Softer Visual Feel
Sharp rectangular corners feel rigid and technical. Rounded corners feel friendly, modern, and approachable. This is why almost every mobile app, operating system, and modern website uses rounded elements — from buttons to cards to profile pictures.
Consistency with UI Design
If your website or app uses CSS border-radius on cards and buttons, images inside those elements should match. An image with sharp corners inside a rounded container looks misaligned. Rounding the image itself ensures visual consistency even when the image is used outside the CSS context (downloaded, shared, or printed).
Platform Requirements
Some platforms display images with rounded corners automatically (iOS app icons, Notion blocks), but others don't. If you need rounded corners in a presentation, document, or platform that doesn't apply CSS styling, you need to round the corners in the image file itself.
How CSS border-radius Relates to Image Files
In web development, border-radius is a CSS property that visually clips the corners of any element — including images. But this is purely a display effect. The underlying image file still has square corners.
img {
border-radius: 16px;
}
This works perfectly on websites, but the moment you download the image, share it in a message, paste it in a Google Doc, or print it, the corners are square again.
BestPNG's round corners tool applies the rounding to the actual pixel data, creating a new image file with permanently rounded corners and transparent areas where the corners were cut.
How to Round Image Corners with BestPNG
Step-by-step:
- Go to bestpng.com/tools/round-corners
- Upload your image (PNG, JPG, or WebP)
- Set the corner radius — use the slider or type a specific pixel value
- Preview the result in real-time
- Download the rounded image as PNG (transparency preserved)
The output is always PNG format because JPG doesn't support transparency. The areas where corners were removed become transparent, allowing the image to sit cleanly on any background.
Radius Values: What Different Settings Look Like
The corner radius determines how much of the corner is removed. Here's a practical reference:
| Radius | Effect | Common Use |
|---|---|---|
| 4-8px | Barely noticeable softening | Subtle UI refinement |
| 12-16px | Gentle rounding, clearly visible | Blog thumbnails, cards |
| 24-32px | Pronounced rounding | App icons, feature images |
| 50-80px | Very rounded, pill-shape on narrow images | Tags, badges, buttons |
| 50% of width | Perfect circle (on square images) | Profile pictures, avatars |
The "right" radius depends on the image size. A 16px radius looks proportionally different on a 200px image versus a 2000px image. As a general rule, aim for a radius that's 3-8% of the image width for a natural look.
Creating Circle Crops
A circle crop is simply a corner radius set to half the image's width (or height, if it's square). This creates a perfect circle, which is the standard shape for profile pictures and avatars across virtually every platform.
To create a circle crop:
- Upload a square image (or crop to square first using BestPNG's crop tool)
- Set the corner radius to 50% (or half the pixel width)
- Download the circular result
If your image isn't square, setting the radius to 50% will create an ellipse rather than a circle. Crop to a 1:1 ratio first for a perfect circle.
Transparent Corners Explained
When corners are rounded, the removed corner areas need to be transparent — not white, not black, but actually empty. This is critical because:
- On a white webpage, white corners look fine — but on a dark page, they create visible white triangles
- In a presentation with a colored background, non-transparent corners look like a mistake
- When layered over other images or patterns, transparency is essential
BestPNG exports rounded images as PNG with a proper alpha channel, ensuring the corners are truly transparent. If you need the image in JPG format (which doesn't support transparency), the transparent areas will be filled with a solid color of your choice.
Design Use Cases for Rounded Images
Blog Post Thumbnails
Rounded thumbnails in a blog grid look more polished than sharp rectangles. A radius of 12-20px is standard for blog cards. Consistent rounding across all thumbnails creates a professional, cohesive grid.
Product Cards in E-commerce
Product images with slightly rounded corners (8-12px) fit naturally inside card components with rounded borders. This is the standard look in modern e-commerce design, used by Shopify themes, Amazon, and virtually every modern online store.
App Icon Design
Mobile app icons on iOS use a specific "squircle" (superellipse) shape with continuous corner curvature. While BestPNG's tool uses standard circular radius (CSS-style), this is close enough for most design purposes. Apple's icon radius is approximately 22.37% of the icon width.
Social Media Graphics
Rounded images in social media posts stand out from the sea of rectangular photos. Use rounded corners for quote graphics, testimonial cards, and feature highlight images. A radius of 16-24px works well for most social dimensions.
Profile Pictures and Avatars
Circle-cropped images (50% radius on a square image) are the universal standard for profile pictures. Every major platform — LinkedIn, Twitter/X, Instagram, Slack, Discord — uses circular avatars. Use BestPNG to create a pre-cropped circular avatar for platforms that don't auto-crop.
Presentation Slides
Images in presentations benefit from subtle rounding (8-12px) to match the modern design language of tools like Keynote, Google Slides, and Figma. Sharp corners in a slide full of rounded UI elements look inconsistent.
Combining Rounded Corners with Other Effects
Rounded corners work well as part of a multi-step workflow:
- Remove the background to isolate the subject
- Resize the image for the target platform
- Add a border if desired
- Round the corners as the final step
Apply rounding last, because subsequent cropping or resizing could affect the corner radius proportions.
Frequently Asked Questions
Can I apply different radius values to each corner?
BestPNG's tool applies a uniform radius to all four corners. For asymmetric rounding (e.g., only top corners rounded), you'd need a CSS approach on a website or a manual editor like Figma.
What happens if I round a JPG image?
The tool converts the output to PNG to support the transparent corners. If you specifically need JPG output, the transparent corners will be filled with a solid background color (white by default).
Will rounding corners reduce my image quality?
No. The pixel data inside the rounded area is preserved at original quality. Only the corner pixels are made transparent. There is no compression or quality reduction applied during the rounding process.
What radius should I use for iOS-style app icons?
Apple uses a squircle (continuous curvature) rather than standard circular border-radius. The effective radius is approximately 22-23% of the icon width. For a 1024x1024 icon, that's about 230px. BestPNG's circular radius at this value will be very close to the Apple shape.
Can I round corners on a transparent PNG?
Yes. If your image already has transparency (like a background-removed photo), rounding the corners works correctly. The existing transparency is preserved, and the corners gain additional transparency.
Conclusion
Rounded corners are a fundamental design element in modern UI, and applying them to image files (not just via CSS) is necessary for consistent visuals across platforms, documents, and presentations.
BestPNG's round corners tool makes this a 10-second task — upload, set your radius, download the result with transparent corners. No Photoshop, no account, no installation.