Free ICO Converter

About ICO Format

The ICO (Icon) format is the standard format for website favicons displayed in browser tabs, bookmarks, and address bars. This converter supports multiple sizes in a single .ico file, which is the modern standard.

Frequently Asked Questions

What is an ICO file?

An ICO file is a binary image format used for icons in Windows applications and website favicons. It can contain multiple images at different resolutions, allowing browsers to display the appropriate size for different contexts.

What sizes should I include?

16x16 and 32x32 are the most common for browser favicons. Include 64x64 and 128x128 for Windows shortcuts and high-DPI displays. 48x48 is useful for legacy support. 256x256 is sometimes used for large icon representations.

How do I use the favicon on my website?

Place the favicon.ico file in your website's root directory, or reference it in your HTML with: <link rel="icon" href="/favicon.ico">. Most browsers will automatically find it in the root directory.

A short history of ICO

Microsoft introduced ICO with Windows 1.0 in November 1985, originally as a resource format for monochrome 32×32 pixel application icons stored inside .EXE and .DLL files. The standalone .ico extension was formalised so icons could be edited and shared independently of executables. Windows 3.x added 16-colour and 256-colour support; Windows 95 made ICO a true multi-resolution container (one file holding 16 / 32 / 48 px renderings, with the OS automatically picking the best for each context); Windows XP added 32-bit alpha for smooth anti-aliased edges and translucent shadows; Windows Vista (2007) introduced 256×256 pixel icons and allowed each entry to store either a classic BMP or a complete PNG file. The PNG-encoded entry is now standard for sizes above 48×48 because a 256×256 32-bit BMP would be roughly 256 KB per icon, wasteful. Many old icon editors still default to BMP-only ICOs and produce files 8–10× larger than necessary.

The format jumped from "Windows internal" to "global web standard" in March 1999 when Microsoft Internet Explorer 5 introduced the /favicon.ico convention. When a user added a page to "Favorites," IE would request /favicon.ico from the website's root and display the 16×16 image alongside the bookmark. The name "favicon" is a portmanteau of "favorites icon", straight from IE's Favorites menu. The convention was never an official W3C standard at launch; Microsoft simply documented the path, browsers and webmasters adopted it, and the rest of the industry followed. Twenty-seven years later every major browser still requests /favicon.ico on first visit even when no <link rel="icon"> tag exists, which is why server logs from any web property in the world show favicon requests from browsers, crawlers, RSS readers and link-preview bots, and 404s when the file is missing.

Why ICO over PNG in 2026

Given how flexible PNG is, why does ICO still matter? Three reasons:

• Windows desktop shortcuts and taskbar pinning. When a user creates a desktop shortcut or pins a site to the taskbar, Windows Explorer needs an ICO to render the shortcut at all the OS's current shell sizes (16, 24, 32, 48, 64, 96, 256). Pointing a .lnk at a PNG produces only one size with bilinear-scaling artefacts.
• Cross-browser favicon compatibility. Modern browsers happily use PNG and SVG via <link>, but the implicit /favicon.ico request still fires on cold visits, and corporate / locked-down environments running older Edge or IE 11 (still extant in 2026 in industrial, healthcare and government contexts) will only render the ICO. A small multi-size .ico in your root is the safest universal default.
• Multi-size in one file. ICO can hold 16, 32, 48, 64, 128 and 256 in a single download, which is what this tool generates. Browsers and OS shells pick the best variant for each context automatically.

The MIME type oddity worth noting: ICO files are technically served as image/vnd.microsoft.icon (the IANA-registered type), but the older image/x-icon is what most servers and CMS templates emit, and it's universally accepted by modern browsers. Both work.

The 2026 favicon recommendation

A modern site shouldn't rely on favicon.ico alone, but it shouldn't skip it either. The "modern minimum" set, advocated by realfavicongenerator.net and the MDN Web Docs, is now:

• favicon.ico (this tool's output), auto-fetched by every browser; required for legacy and IE/old-Edge users.
• favicon.svg: single file, scales to any density; supports light/dark via prefers-color-scheme. Supported in Chromium 80+ (early 2020) and Firefox 41+ (2015), but Safari only added support in version 17 (September 2023). 2026 is the first year you can realistically rely on SVG-only across most browsers.
• favicon-32x32.png and favicon-16x16.png: pixel-perfect raster fallbacks for browsers that prefer PNG over SVG when both are listed.
• apple-touch-icon.png (180×180), for iOS home-screen shortcuts. Apple does not use ICO or SVG; PNG is required.
• android-chrome-192x192.png and android-chrome-512x512.png: referenced from a web manifest for Android launchers and PWA installs.
• manifest.webmanifest: declares the PNG icons, theme colour, app name and display mode for PWAs.

The HTML head block exposes all of this:

<link rel="icon" href="/favicon.ico" sizes="any">
<link rel="icon" type="image/svg+xml" href="/favicon.svg">
<link rel="apple-touch-icon" href="/apple-touch-icon.png">
<link rel="manifest" href="/manifest.webmanifest">
<meta name="theme-color" content="#ffffff">

The sizes="any" attribute on the .ico link tells modern browsers "this file contains arbitrary sizes, use it as a fallback only," so they prefer the SVG when available. The 2024–2026 trend in best-practice guides is to prune aggressively: ship those four files plus a manifest. The old "16-file favicon packages" with mstile and yandex tiles are no longer recommended unless you specifically target those platforms.

Inside an ICO file

For the curious: the binary layout is straightforward. A short ICONDIR header (6 bytes, reserved, type=1 for icons, count of images), followed by N ICONDIRENTRY records (16 bytes each, listing width / height / colour count / size / file offset), followed by N image bitmaps. Each image entry can be either an old-style BMP/DIB or (since Vista) a complete PNG file with its own header. The ICONDIRENTRY record always stores width and height as bytes, with 0 meaning 256 (the maximum). This is why ICO supports up to 256×256 but not larger; the format would need to be revised to store bigger images.

Tools to test what you generate

• realfavicongenerator.net's checker: visits your site and reports per-platform rendering issues. Strict but accurate.
• favicon.io's tester: quick visual check across mocked browser tabs.
• Browser DevTools. Force-refresh with Ctrl+F5 (or Cmd+Shift+R) to bypass favicon cache, which is famously aggressive, Safari in particular caches favicons across restarts and sometimes ignores updates for hours.
• Direct URL. Visit yoursite.com/favicon.ico in a new tab to confirm the file is actually served. A common issue: the file exists but the server returns 404 because it's outside the configured static-file path.

When you'd reach for this

• Building a new site's favicon set. Generate the multi-size .ico here, plus a SVG and apple-touch PNG using other tools.
• Updating an existing favicon. Re-export the multi-size .ico after a logo refresh.
• Pinning a Windows desktop shortcut to a custom-icon URL.
• Generating an Electron / Tauri app icon: Windows desktop apps want ICO for the executable's resource section.
• Replacing a tofu / 404 favicon on a previously-shipped site that never had one.

More questions

My favicon updated but my browser still shows the old one, why?

Favicon caching is famously aggressive. Browsers cache favicons across restarts and don't always honour HTTP cache-control headers. Force-refresh (Cmd+Shift+R on Mac, Ctrl+F5 on Windows) usually works in Chromium and Firefox; Safari sometimes needs a full quit-and-restart, and on iOS the home-screen icon may need the page to be re-added entirely. Adding a query string (/favicon.ico?v=2) forces a refresh in most browsers but doesn't always work for the implicit /favicon.ico request, for that, declare the new URL in a <link rel="icon"> tag.

What sizes should I include?

For browser favicons: 16 and 32 are essential. 48 helps with high-DPI Windows tabs. For Windows desktop shortcuts and taskbar pinning: include 64 and 128 (and 256 for the largest "Extra large" Explorer view). The default selection on this tool (16/32/48/64) covers 99% of cases. Adding 128 or 256 increases file size noticeably (PNG-encoded 256×256 alone is around 30–40 KB) so include them only if you actually need Windows shell rendering.

Should I use a transparent background?

Almost always, yes, modern browsers display favicons against the tab's chrome colour, which differs between light mode, dark mode and tab pinning. Transparent PNGs (or transparent input to the converter) produce clean edges across all backgrounds. The exception is logos that are unreadable without a coloured backing, for those, baking in the background colour is fine. PNG and ICO both support full alpha; JPEG doesn't, so JPG inputs lose transparency.

Is favicon.ico still really needed in 2026?

Yes, but only as a fallback. Every browser still implicitly requests it on first visit even with modern <link> tags in place; Windows desktop shortcuts and taskbar pinning need it; corporate environments still running IE11 or old Edge (yes, those exist in healthcare, manufacturing and government) need it. A 4–8 KB multi-size .ico in your root is the safest universal default, paired with SVG and PNG via <link> tags for everyone else.

Does anything get sent to a server?

No. The image is decoded in your browser, scaled to each requested size via the Canvas 2D API, and assembled into an ICO binary by JavaScript. The result is downloaded straight to your device. Nothing about your image (including any logo design you might still be iterating on) leaves the page.

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