How to open .ICO files (Windows icons) on Android, Windows and Linux

You’ve found a favicon.ico in a website project, unpacked an icon pack full of .ico files, or downloaded a .cur cursor. Double-clicking it on Windows may do something unhelpful, and on a phone it isn’t obvious what could open it at all.

Folders opens ICO icons and CUR cursors in its image viewer on Android, Windows and Linux, and can make an ICO from any picture. It’s free and works offline.

What is an .ICO file?

ICO is the icon format of Windows. Unlike most image files, one ICO is a small container that can hold several versions of the same icon at different sizes, typically 16 × 16, 32 × 32, 48 × 48 and 256 × 256 pixels, so Windows can pick a sharp one for the taskbar, the desktop or a big folder view. Each version is stored either as a bitmap, laid out much like a BMP, or, for large sizes since Windows Vista, as a compressed PNG.

Websites use ICO too. Browsers look for a file called favicon.ico at the root of a site for the little picture in the tab. Many favicon.ico files are really PNGs under that name, and browsers don’t mind.

Extension	What it is
.ico	An icon: one or more pictures of the same image at different sizes and colour depths
.cur	A static mouse pointer. Same structure as an ICO, plus a “hotspot”: the exact pixel that does the clicking

The two are so close that their first four bytes differ by a single number: an ICO starts 00 00 01 00, a CUR 00 00 02 00. Animated pointers use a different format, .ani.

How to open an .ICO file with Folders

Android

1. Install Folders from the download page and allow file access.
2. Icon packs often arrive as a ZIP. Open the ZIP in Folders and tap an icon inside it to see it straight away, or extract the lot first.
3. Tap an .ico or .cur file to open it in the image viewer. From another app, choose Open with → Folders.

Windows and Linux

1. Browse to the icon in Folders and double-click it.
2. On Windows the installer adds Folders to File Explorer’s Open with menu for ICO and CUR files: right-click → Open with → Folders.

What you can do with an ICO in Folders

• See the icon, zoom in to check its edges, and move through a folder of icons with swipes or the arrow keys.
• Turn an icon into a normal picture. Select it and choose Convert to ▸ PNG, or JPEG, WebP and the rest of the list. This works for cursors too: Folders reads CUR files itself.
• Make an icon from a picture. Select a PNG, JPG or other image and choose Convert to ▸ ICO (icon). Folders makes a square icon up to 256 × 256 pixels, with your picture fitted and centred on a transparent background, so a wide logo isn’t stretched. A PNG with a transparent background gives the cleanest result.
• Resize… first if you want a smaller icon, giving the size in pixels or as a percentage.
• Details, Share and Open with another app work as for any picture.

An ICO made this way holds one picture, which Windows scales down for smaller sizes. If you want hand-tuned 16- and 32-pixel versions in the same file, build the icon in GIMP, where each size is a layer.

Other ways to open .ICO files

• GIMP (free): opens every size in an ICO as a separate layer and exports multi-size icons.
• A web browser: drag the file into a tab to see it.
• XnView MP or IrfanView on Windows show both ICO and CUR files.
• Online favicon generators if you need a full set of website icons.

Problems opening an .ICO file?

The icon looks blurry. An ICO holds several sizes, and an app may pick a small one and stretch it. If the file only contains small sizes, there’s no sharp version to show; look for a 256-pixel version of the icon.

An old program can’t read it. Icons with PNG-compressed pictures, usual for 256-pixel sizes, aren’t understood by software from before Windows Vista. Convert a copy to PNG, or rebuild the icon with bitmap pictures in GIMP.

Windows won’t take your PNG as an icon. The Change Icon dialog for shortcuts and folders wants .ico files (or icons inside programs). Use Convert to ▸ ICO first.

A .cur works but an .ani doesn’t. Animated pointers (.ani) are a different format; Folders can only show their raw bytes in its hex viewer. Use a cursor editor for those.

Questions people ask

How do I convert a PNG to ICO? In Folders, select the PNG and choose Convert to ▸ ICO (icon). The icon is saved beside the PNG, which stays as it was.

Can I open an .ico file on Android? Yes. Folders shows ICO and CUR files from any folder, or straight from inside a ZIP.

Is an .ico file safe? An icon is just a few pictures; it can’t run anything. Be wary of names that only look like icons, such as icon.ico.exe: that’s a program, and because Windows hides known file endings by default, it can appear as icon.ico.

ICO vs PNG: which do I need? PNG for most websites and apps (modern browsers accept PNG favicons); ICO for Windows shortcuts, folders and programs, and for the classic favicon.ico.

ICO pictures are often stored like BMPs: see the BMP guide. For transparent source images, read the PNG guide, or browse all 382 file types Folders opens.