BYTETOOLS

PNG to ICNS Converter

Turn one square PNG into a macOS .icns icon file containing every size from 32 to 1024 pixels, built entirely in your browser.

Drop a square PNG (1024 × 1024 is ideal)The .icns container is written in your browser — your artwork is never uploaded

macOS apps ship their icon as a single .icns file holding every size at once. Choose your artwork and this tool renders each slot and writes the container by hand.

What is the PNG to ICNS Converter?

macOS apps ship a single . icns file that carries the icon at every size the system might need — a small one for a Finder list, a huge one for the App Store.

  • Eight macOS icon slots from 32 × 32 up to 1024 × 1024, each individually selectable
  • Stepped canvas downscaling so small sizes stay legible instead of turning to mush
  • Non-square sources are centre-cropped automatically
  • Container written by hand with the icns magic, total length and per-size typed chunks
  • Preview of every rendered size with its PNG byte count
  • Runs completely offline in your browser — the artwork is never uploaded

How to use the PNG to ICNS Converter

  1. 1

    Drop a square PNG — 1024 × 1024 gives the best result at every size.

  2. 2

    Untick any icon sizes you do not need; each one is labelled with the macOS context it is used in.

  3. 3

    Click Build .icns and watch each size render with a preview.

  4. 4

    Check the container size, then click Download .icns and drop the file into your app bundle or Xcode project.

About the PNG to ICNS Converter

macOS apps ship a single .icns file that carries the icon at every size the system might need — a small one for a Finder list, a huge one for the App Store. This tool rescales your artwork to each of those slots with stepped high-quality resampling, then writes the .icns container by hand: the icns signature, the total byte length and one typed chunk per size holding raw PNG data.

The type codes are the ones Apple's own iconutil emits from an .iconset folder: ic11 and ic12 for the retina 16 pt and 32 pt slots, ic07 and ic13 for 128 pt, ic08 and ic14 for 256 pt, and ic09 and ic10 for 512 pt including the 1024-pixel retina version. Tick only the slots you want and the file shrinks accordingly.

Nothing is uploaded. Your artwork is drawn to a canvas, exported as PNG by the browser and assembled into the container in JavaScript on your own machine, which matters when the icon belongs to an unreleased product. A square 1024-pixel source gives the sharpest result because every other size is derived from it.

Frequently asked questions

How do I make an ICNS file without a Mac?

Drop a square PNG into this tool and it renders every macOS icon size and writes the .icns container for you in the browser. You get the same file structure Apple's iconutil produces, without needing macOS or the command line.

What size should my source image be for an ICNS file?

1024 × 1024 pixels is ideal because that is the largest slot in the container, and every smaller size is scaled down from it. A smaller source still works but the biggest icon will look soft.

Which sizes does a macOS icon file need?

A complete set covers 16, 32, 128, 256 and 512 points at both standard and retina scale, which is 32 through 1024 pixels. Including all of them is safest, but you can leave out the largest slots if the icon is not going to the App Store.

Can I open the .icns file to check it?

Yes. On macOS you can open it in Preview or run iconutil against it, and the sizes listed here are exactly the ones it will report. The tool also shows the byte count of each embedded PNG before you download.

Is my icon artwork uploaded?

No. Rescaling, PNG export and container assembly all happen in your browser with a canvas and plain JavaScript, so the artwork never leaves your device.

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