How do I round the corners of a PNG image?
A PNG Corner Rounder is a digital tool that instantly clips the sharp, 90-degree edges of an image to create smooth, curved borders. Using our browser-based engine, you can perfectly crop an image into a circle, apply independent corner radii for UI chat bubbles, and automatically add solid backgrounds or colorful border strokes. All processing happens locally on your device, ensuring a fast, private export that preserves your transparent alpha channel.
🔲 PNG Corner Rounder
Smooth out sharp edges. Add perfect circular crop, independent rounded corners, borders, and solid backgrounds to your transparent images safely in your browser.
How to Use the Corner Rounder
Creating the perfect curved borders or circular avatars takes just seconds:
- Upload Your Image: Drag and drop your PNG or JPG into the upload zone.
- Adjust the Corner Radius: * Use the Radius (All) slider to curve all four corners simultaneously.
- Pro Tip: Sliding it to 50% will create a perfect circular crop (if your image is a square) or an oval (if your image is a rectangle).
- Unlink Corners for Custom Shapes: Uncheck “Link All Corners” to adjust the Top Left, Top Right, Bottom Right, and Bottom Left independently. This is ideal for creating app icons or message bubbles where one corner remains sharp.
- Add a Border or Background: Toggle the Border switch to add a stroke around your new curved shape, or toggle the Background switch to fill the empty space behind your cut-out subject with a solid color.
- Export: Click Export PNG to save your smoothly rounded image directly to your device.
Pro-Level Shaping: Why This Engine is Better
Based on the most common searches from app developers and social media managers, we built this engine to solve the specific clipping errors caused by standard CSS border-radius tools.
1. Dynamic Boundary Insetting (No Clipped Borders)
When you add a thick border to an image in a basic photo editor, the program often draws the stroke on the mathematical edge of the canvas. This causes the outside half of the border to bleed off the screen, leaving you with a clipped, ugly edge. Our engine uses a dynamic inset algorithm. If you add a 20px border, the engine calculates the math, shrinks your clipping path inward by exactly 10px, and draws the stroke perfectly inside the bounds of the image, keeping it razor-sharp.
2. Creating Circular Profile Avatars
If you run a Discord server or a Twitch channel, you need perfectly circular avatars. Standard cropping tools are cumbersome. With this tool, simply upload a square image, drag the radius slider to 50%, turn on the Border feature to add your brand color, and download. It creates a flawless, perfectly anti-aliased circle with transparent padding.
3. Designing App Icons (Independent Radii)
UI/UX designers often need specific corner controls. For example, a “Reply” chat bubble might have three rounded corners and one sharp 90-degree corner pointing at the user. By unchecking the link toggle, you have absolute pixel-perfect control over every individual vertex of your graphic.
4. Absolute Privacy
Clipping personal profile pictures or unreleased app assets on free online tools is a privacy risk. We engineered this tool using native HTML5 Canvas APIs. All geometrical clipping and rendering happens directly within your browser’s memory. Your files are never uploaded to our servers, ensuring total privacy.
Frequently Asked Questions (FAQ)
What does 50% radius mean?
Instead of using absolute pixels (which can be confusing if you don’t know the exact size of your image), our engine calculates the curve as a percentage of your image’s shortest side. At 50%, the curve spans exactly from the center of the edge to the corner, resulting in a perfect circle or oval.
Why isn’t my image becoming a perfect circle?
To make a perfect circle using a corner rounder, your original image must have a 1:1 aspect ratio (a perfect square). If you upload a rectangle and set the radius to 50%, it will create an oblong pill or oval shape. If you need to make your image a square first, use our Aspect Ratio Changer tool.
Will the corners be transparent when I download it?
Yes. When the engine cuts away the sharp corners of your image, the space left behind becomes a true transparent alpha channel. When you upload the PNG to a website, the background of the page will show through those rounded corners seamlessly.
Does the engine reduce image quality?
No. The engine uses your browser’s native, high-quality image smoothing algorithms. It locks in your original file’s dimensions, ensuring the final PNG is never compressed or downscaled.