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BulkPicTools

Round Image Corners — Free, Batch, No Upload

Add rounded corners to images — free, batch, no upload. Per-corner control, Circular or Smooth curve style, transparent PNG output. Process entire folders at once.

Drop images to round corners

Batch process any number of images. Output is always PNG to preserve transparent corners.

PNG transparency preserved · Batch processing · 100% local
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Key Features of Round Image Corners

Per-Corner Control

Set each corner independently — top-left, top-right, bottom-right, bottom-left. Or use uniform mode for quick consistent rounding. **Lock diagonal pairs** (TL=BR, TR=BL) for asymmetric designs in one click.

Batch Process Entire Folders

Drop 50, 100, or 500+ images at once. One set of settings applies to all — consistent corner radius across your entire icon library, product catalog, or social media asset set. **No file count limit.**

Circular & Smooth Curve Styles

Circular uses standard arc geometry. Smooth uses Bézier curves for an **Apple-style squircle** feel — the curve starts earlier and flows more naturally. The difference is subtle but designers notice immediately.

Guides & Tips

Why your output is always PNG — and why that's the right choice

When you add rounded corners to an image, the four corner regions become transparent. That transparency has to live somewhere in the file format. PNG supports alpha channel transparency natively — every pixel can have an opacity value from fully transparent to fully opaque. JPEG does not support transparency at all; if you save a rounded-corner image as a JPEG, the transparent corners will be filled with a solid color (usually white or black), completely defeating the purpose of rounding the corners in the first place.

This is why this tool always outputs PNG regardless of whether your input was a JPG, PNG, or WebP. It is not an arbitrary restriction — it is the technically correct behavior. The output file is larger than a JPEG would be, because PNG is a lossless format, but the transparency is preserved exactly. If the PNG file size is a concern after rounding, run it through the Bulk Image Compressor to reduce it — all processing stays local.

The one exception: if you choose a solid background color instead of transparent (using the Background color picker), the corner regions will be filled with your chosen color rather than being transparent. In this case, a JPEG output would technically be possible, but the tool still outputs PNG to maintain lossless quality of the image content itself.

Circular vs. Smooth corners: what's the actual difference?

Both styles use the same corner radius value — the difference is in the mathematical curve that defines the corner shape.

Circular (standard arc)

A circular arc is the curve you get from CSS border-radius or HTML Canvas's roundRect() function. The corner is a quarter-circle: the curve has a constant radius at every point. It transitions abruptly from the straight edge to the curved corner at a precise point. This is the standard rounded corner you see in most UI frameworks, Windows UI elements, and web design that hasn't been updated recently.

Smooth (squircle / superellipse)

A smooth corner uses cubic Bézier curves instead of a circular arc. The key difference is that the curve begins earlier — instead of transitioning sharply from a straight line to a circular arc, the curvature builds up gradually from zero. This is the corner style used by Apple for iOS app icons since 2013, and by Figma for its frame corner rounding. It feels more natural because it more closely matches how corners look in the physical world (the edge of a rounded piece of metal, for example).

The mathematical basis is the superellipse: |x/a|^n + |y/b|^n = 1. When n=2, you get an ordinary ellipse. When n approaches infinity, you get a square. The sweet spot for app icons and modern UI is n≈4–5, which the Smooth option approximates using Bézier control points. The visual result is a corner that looks slightly more "relaxed" or "pillow-like" compared to the harder transition of a circular arc.

For most use cases — product images, social media cards, general design work — either style works. For app icons intended to sit next to iOS or macOS system icons, Smooth is the correct choice. For UI elements in a design system that uses border-radius, Circular matches what the browser renders exactly.

Per-corner radius: when to use it and what it enables

Uniform rounding — where all four corners share the same radius — covers the majority of use cases. But there are specific design patterns where independent corner control matters.

Tab navigation active state

A selected tab often has rounded top corners but square bottom corners (or vice versa), creating a connected look with the content panel below. Setting TL=TR=16px with BR=BL=0px produces this effect.

Directional cards and banners

Cards that "point" in a direction — like a speech bubble callout or a banner with a directional accent — may use a large radius on three corners and zero on the corner that points toward the referenced element.

Asymmetric product images

E-commerce product cards sometimes use different radii on opposing corners to create a distinctive brand look. Large radius top-left and bottom-right with small radius top-right and bottom-left creates a diagonal rhythm when cards are arranged in a grid.

The lock diagonal buttons

The "Lock TL=BR" and "Lock TR=BL" buttons let you set opposing diagonal corners to the same value simultaneously. This is the most common asymmetric pattern: different values between the two diagonal pairs, but symmetry within each pair. Most design systems that use asymmetric rounding follow this convention — it creates visual balance while still differentiating the corners.

Batch processing rounded corners: app icons, product catalogs, and design assets

The batch mode is the feature that separates this tool from most alternatives. round-corner.imageonline.co and similar tools process one image at a time. allrounderimagetool.com supports batch but offers only a single uniform radius slider. pinetools has a dedicated bulk version but no per-corner control.

App icon sets (iOS, Android, macOS)

A complete iOS app icon set contains 20+ sizes: 20×20, 29×29, 40×40, 60×60, 76×76, 83.5×83.5, 1024×1024, and several @2x and @3x variants. If you're rounding corners on exported icon assets before submission, batch processing with a consistent percentage-based radius (rather than pixel-based) ensures the rounding is proportionally correct at every size. Set unit to % and use 22% — this approximates the iOS system icon corner radius applied by the operating system at display time.

Product image libraries

E-commerce product photos often need consistent corner rounding for category pages, thumbnail grids, and social media posts. Drop the entire product folder, set a radius, and process in one run. Output filenames preserve the original name with "-rounded" appended, making it straightforward to replace files in the original asset folder.

Design system screenshots

Documentation screenshots for design systems, component libraries, or app store listings often need rounded corners added before placement in Figma or Keynote. The transparent PNG output drops cleanly into any design tool frame without needing masking or clipping. If you're preparing multiple screenshots for an App Store submission (which requires specific sizes and often rounded corners for display), batch processing all screenshots at once takes seconds instead of minutes. After rounding, if you need to add a watermark or copyright notice, the Image Watermark tool handles that in the same local, no-upload workflow.

Rounded corners vs. circle crop: which do you need?

This question comes up often enough to be worth answering directly, because the two tools are related but serve different purposes.

Rounded corners (this tool)

Applies a corner radius to a rectangular image. The output shape is a rounded rectangle — the image remains its original aspect ratio and proportions, just with soft corners instead of sharp 90-degree angles. The image content is fully preserved; you only lose the four corner triangles. Best for: app icons, product cards, thumbnails, UI screenshots, any image that needs softer edges while remaining fundamentally rectangular.

Circle crop (Circle Image Cropper)

Crops the image into a perfect circle. This is equivalent to setting rounded corners to 50% on a square image — but the Circle Cropper also handles the aspect ratio: it crops the image to a square first, then applies the circular mask. Best for: profile pictures, avatars, social media headshots, any context where the image needs to be a perfect circle rather than a soft rectangle.

The practical rule: if you want to see most of the image and just soften the edges, use rounded corners. If you want a profile picture circle or avatar, use the circle cropper. At a corner radius of exactly 50% on a square image, the two tools produce identical output — a perfect circle.

How to use

1

Upload images

Drag and drop images or click to browse. JPG, PNG, and WebP accepted. **No file size limit**, no count limit.

2

Set corner radius

Choose uniform rounding with a single slider, or switch to per-corner mode for independent control. Set values in **px or %**.

3

Pick curve style and background

Choose Circular (standard arc) or Smooth (squircle Bézier). Set background to **transparent** or any custom color.

4

Download as PNG

Download individually or **batch ZIP** — all outputs are PNG to preserve transparent corners. Filenames get a "-rounded" suffix.

Frequently Asked Questions About Round Image Corners

Rounded corners create transparent corner regions — areas where the original image is removed. PNG supports this transparency natively. JPEG does not support transparency at all; corners in a JPEG would be filled with a solid color, defeating the purpose of rounding them. This is why the output is always PNG regardless of your input format. If you choose a solid background color (instead of transparent), the corners will be filled with that color, but the output remains PNG to keep image quality lossless. If the PNG file is larger than needed, use the Bulk Image Compressor to reduce the file size.