Rounded Corners Image

Introduction

Rounded corners signal modern UI design — from avatar circles on social profiles to card thumbnails in dashboard mockups. CSS border-radius handles live web layouts, but static image exports for slide decks, email templates, and app store screenshots often need the corner clip baked into the PNG itself. Achieving consistent radius across a batch of assets without Figma access on a travel laptop is a common friction point. Cloud "round image corner" tools exist, but they upload your brand photography and team headshots to unknown servers.

Certoflow's Rounded Corners Image tool clips any raster image to a custom corner radius and exports PNG with transparent regions outside the rounded rectangle. Adjust radius with a slider, preview live, and download — all in the browser via Canvas clipping paths. Light and dark theme support helps you judge edge anti-aliasing against both light and dark preview backgrounds.

What this tool does

The rounded corner workflow targets avatars, cards, and marketing tiles:

1. Upload — load JPEG, PNG, or WebP files with batch support.
2. Set corner radius — choose pixel radius from subtle rounding to full circle on square crops.
3. Process — apply rounded clip to active image or entire batch.
4. Download — save PNG with transparent corners outside the clip region.

Corners outside the rounded rectangle become fully transparent in PNG output — ideal for overlaying on varied backgrounds in slides and email HTML.

Dimensions of the output canvas match the source bitmap. Only the corner geometry changes.

No server processing. No forced watermark.

How it works

Certoflow loads the image to canvas at native resolution, defines a rounded-rectangle path using the canvas roundRect API (or equivalent path arc composition), clips drawing to that path, and paints the source image inside. Pixels outside the path remain transparent in PNG export.

For a perfect circle on square images, set radius to half the image width — a 200-pixel square with 100-pixel radius produces a circular clip. Avatar workflows often use 24–48 pixel radius on smaller square crops for subtle rounding without full circular masks.

Batch mode applies the same radius to every loaded file. Change radius and reprocess if previews look too sharp or too circular for your design system tokens.

Processing is entirely client-side. Certoflow does not upload logos or portraits.

Radius recommendations

Image size	Suggested radius	Visual result
64×64 avatar	12–16px	Subtle rounded square
128×128 avatar	24–32px	App-icon style rounding
200×200 square	100px	Full circle
400×300 card	16–24px	Modern card thumbnail

Crop to square with Crop Image before applying circle-radius math when you need perfect circular avatars from rectangular photos.

Real-world examples

Team page headshots

HR exports rectangular portrait JPEGs from the photographer. Crop to square, apply 48-pixel rounded corners, and upload PNGs to the static site team grid where CSS radius is inconsistent in legacy email embeds.

App store screenshot cards

A mobile developer wraps promotional screenshots in rounded cards for Google Play feature graphics. Batch-process six PNGs with identical 20-pixel radius for visual consistency.

Email marketing tiles

An ESP template places product images on colored table cells. Rounded PNG corners with transparency avoid white fringing that JPEG squares cause on non-white backgrounds.

Design system documentation

A UX team documents avatar specs: 96-pixel square source, 16-pixel radius export. Rounded Corners Image produces reference PNGs matching the written spec without opening Sketch.

Social profile picture prep

An influencer prepares a square logo mark with circular clip (radius = half width) for platforms that crop uploads to circles but benefit from pre-clipped PNG uploads with anti-aliased edges.

Common mistakes

Using JPEG output expectation. Rounded corners require transparency outside the clip — this tool exports PNG. Convert to JPEG only if you accept white matte corners on non-white backgrounds.

Applying circle radius to non-square images. A 400×200 image with 100-pixel radius produces a stadium shape, not a circle. Crop square first for circular avatars.

Radius larger than half the shorter side. Canvas clamps path geometry; extreme values may not behave as expected. Keep radius at or below half the minimum dimension for predictable rounding.

Ignoring anti-aliasing on dark backgrounds. Preview PNG on both light and dark backgrounds before publish — fringe pixels may need radius adjustment or source padding.

Rounding before cropping. Crop to final composition first, then round. Rounding a wide photo keeps empty transparent corners that waste layout space.

Expecting drop shadows or borders. This tool clips corners only. Add shadows in design tools or CSS after export.

Batch processing mixed dimensions with one radius token. A 48px radius looks subtle on 512px images but circular on 96px images. Group similar sizes per batch.

Related tools

Prepare square sources with Crop Image and scale with Image Resizer. Favicon Generator produces small square brand icons for tabs. Flip Image fixes mirrored selfies before rounding. PNG to JPG flattens transparency when a JPEG destination requires it — corners become white. Image Compressor shrinks rounded PNGs for web.

FAQ

Are my images uploaded to a server?

No. Corner clipping uses Canvas locally in your browser.

Is the background outside corners transparent?

Yes. PNG output includes alpha outside the rounded clip region.

What radius works for avatars?

Try 24–48px on square crops, or half the image width for a full circle effect.

What formats can I upload?

JPEG, PNG, and WebP. Output is PNG with transparency.

Can I batch apply the same radius?

Yes. Load multiple files and process all with shared radius settings.

Does rounding change image dimensions?

Canvas dimensions match the source width and height. Transparent corners occupy the same pixel grid.

Can I use this offline?

Yes, after the page loads.

Will JPEG sources get transparency?

Yes in PNG output. Original JPEG had no alpha, but clipped corners export as transparent PNG.

How do I get a perfect circle?

Use a square crop and set radius to half the side length.

Does Certoflow support light and dark theme?

Yes. Preview panels follow Certoflow's light and dark interface themes.