Image guides
How to Convert PNG to ICO in Your Browser
A PNG to ICO conversion isn’t just a file-extension swap — it builds a real multi-resolution Windows icon container, embedding several resized copies of your image as their own compressed entries. This guide covers how that container is built, what happens to non-square images, and when ICO is actually the format you need.
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How PNG becomes ICO
The browser resizes the source PNG to each requested square size — 16 through 256 px by default, or a single size you choose — re-encodes each resized copy as genuine PNG-compressed image data, then packages every size into one ICONDIR-format .ico container. That’s the difference between a real ICO and a fake one that’s just a renamed bitmap with a swapped extension.
What changes when you convert
Alpha transparency survives at every embedded size, since each entry is real PNG data rather than a flattened bitmap. A non-square source gets stretched, not cropped, to fill the square canvas at each size, which visibly distorts non-square subjects — starting from square source art avoids this entirely.
When ICO is the right choice — and when it isn’t
ICO is specifically for Windows application icons, desktop shortcuts, and favicons, where the OS or browser expects exactly that multi-size container format — nothing else reads or benefits from an ICO. If you just want a small square image for the web, PNG itself (or a single resized copy) is simpler and more broadly usable; ICO’s value is entirely in the Windows-icon convention.
Limitations and privacy
Every generated ICO is a real, inspectable icon container, not a renamed image with a swapped extension. Conversion runs locally in your browser; the file is not uploaded to Looty Tools servers.
Convert PNG to ICO FAQ
- Can I choose just one icon size instead of the full package?
- Yes. You can pick a single size instead of the default 16–256 px multi-size package.
- Does stretching a non-square image look bad?
- It depends on the subject — a non-square source is stretched, not cropped, to fill each square canvas, so cropping to square beforehand gives a more predictable result.
- Are the embedded icons compressed or raw bitmaps?
- Compressed. Every size is embedded as genuine PNG-compressed image data, not a raw bitmap.
- What’s the largest icon size in the default package?
- 256 px, alongside 16, 32, 48, 64, and 128 px in the same .ico file.
- Is my image uploaded anywhere?
- No. Conversion runs locally in your browser and does not upload your file to Looty Tools servers.
Related guides
- Convert JPG to ICOConvert a JPG, JPEG, or JFIF file to a real Windows ICO icon locally: generate a single size or a multi-size package (16–256 px) and download the result.
- Best Format by Use CaseA quick reference for choosing between JPG, PNG, WebP, AVIF, TIFF, ICO, TGA, QOI, and PPM based on what you are actually trying to do.
- Convert Images Without UploadingLearn what browser-local image conversion means on Looty Tools, what stays on your device, and how Image Converter avoids a conversion upload.
