ICO vs RAW — Differences, File Size & When to Use Each

Q: What is an ICO file?

ICO (Icon) is Microsoft&#039;s 1985 multi-resolution icon format, originally shipped with Windows 1.0. A single .ico file holds multiple sizes (16×16, 32×32, 48×48, 256×256) so the OS can pick the best one for the current display context. Since 1999, every website uses a favicon.ico to show its icon in browser tabs.

Q: How do I open an ICO file?

On Windows, ICO files open natively in File Explorer and Photos. On macOS, Preview handles basic display. For editing, use GIMP (free), Photoshop with a plugin, or dedicated icon editors like IcoFX.

Q: How do I convert PNG to ICO?

Use the PNG-to-ICO converter on KaijuConverter — upload a PNG (ideally square, at least 256×256) and download a multi-resolution ICO with all standard favicon sizes embedded.

Q: What size should a favicon.ico be?

A complete favicon pack includes 16×16, 32×32, 48×48, and 256×256 px variants all in one ICO file. The total file size is typically 5-15 KB. Browsers automatically pick the right size for tabs, bookmarks, and desktop shortcuts.

Q: ICO vs PNG for web icons: which?

ICO for /favicon.ico (every browser requests this URL automatically). PNG for everywhere else — social media profile images, in-page icons, app logos. Modern favicon best practice includes both an .ico at the root and multiple .png sizes referenced via &lt;link&gt; tags in HTML.

ICO vs RAW

A detailed comparison of ICO Icon and Generic RAW Image — file size, quality, compatibility, and which format to choose for your workflow.

Convert RAW → ICO

ICO

ICO Icon

Raster & Vector Images

ICO is the icon file format used for favicons and Windows application icons. A single ICO file can contain multiple image sizes and color depths for different display contexts.

About ICO files

RAW

Generic RAW Image

Raster & Vector Images

RAW is a generic term for files containing minimally processed data from a camera image sensor. Various camera manufacturers use proprietary RAW variants, but the term broadly refers to any unprocessed sensor capture that retains maximum editing flexibility.

About RAW files

Strengths Comparison

ICO Strengths

Multi-resolution: one file, many sizes, OS picks the right one.
Universal favicon support in every browser since IE5.
Supports transparency (1-bit since 1985, full alpha since XP).
Tiny file size — an entire favicon pack typically fits in under 15 KB.
No licensing or patent concerns — fully in the public domain spec-wise.

RAW Strengths

Every bit of sensor data preserved for post-processing latitude.
Higher bit depth (12-16 bits) than JPEG (8-bit) — smoother gradients.
Non-destructive editing in raw processors.
Rich metadata (EXIF, makernotes, camera settings).

Limitations

ICO Limitations

Cannot compress continuous-tone images efficiently — use PNG or WebP for photos.
Format is essentially frozen in 1999 — no HDR, no wide gamut, no modern features.
Maximum image dimension is 256×256 px (inside an ICO container).
Editing requires specialized tools — most image editors treat it as a curiosity.

RAW Limitations

Proprietary per brand — Canon CR2 will not open in a pure-Canon-free processor.
Huge files compared to JPEG.
Requires dedicated software (Lightroom, Capture One, Darktable, etc.).
No universal standard — DNG aims to solve this but adoption is partial.

Technical Specifications

Specification	ICO	RAW
MIME type	image/vnd.microsoft.icon	—
Max resolutions per file	65 535 images	—
Max single image size	256×256 px	—
Color depths	1, 4, 8, 24, 32 bits per pixel	—
Compression	Uncompressed bitmap or embedded PNG (Vista+)	—
MIME types	—	image/x-* (varies by vendor)
Common extensions	—	.cr2, .cr3, .nef, .nrw, .arw, .raf, .orf, .rw2, .dng, .pef, .x3f, .raw
Bit depth	—	12-16 bits per pixel
Typical containers	—	TIFF/EP variants with vendor makernotes
Universal exchange format	—	DNG (Adobe)

Typical File Sizes

ICO

Classic favicon (16×16 only) < 2 KB
Multi-size favicon pack (16/32/48/256) 5-15 KB
Full Windows app icon set 20-100 KB

RAW

24 MP raw (APS-C/FF, 14-bit) 25-50 MB
45 MP raw (high-end FF) 50-90 MB
100 MP medium-format raw 120-200 MB

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Convert between ICO and RAW online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.

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Frequently Asked Questions

ICO (Icon) is Microsoft's 1985 multi-resolution icon format, originally shipped with Windows 1.0. A single .ico file holds multiple sizes (16×16, 32×32, 48×48, 256×256) so the OS can pick the best one for the current display context. Since 1999, every website uses a favicon.ico to show its icon in browser tabs.

On Windows, ICO files open natively in File Explorer and Photos. On macOS, Preview handles basic display. For editing, use GIMP (free), Photoshop with a plugin, or dedicated icon editors like IcoFX.

Use the PNG-to-ICO converter on KaijuConverter — upload a PNG (ideally square, at least 256×256) and download a multi-resolution ICO with all standard favicon sizes embedded.

A complete favicon pack includes 16×16, 32×32, 48×48, and 256×256 px variants all in one ICO file. The total file size is typically 5-15 KB. Browsers automatically pick the right size for tabs, bookmarks, and desktop shortcuts.

ICO for /favicon.ico (every browser requests this URL automatically). PNG for everywhere else — social media profile images, in-page icons, app logos. Modern favicon best practice includes both an .ico at the root and multiple .png sizes referenced via <link> tags in HTML.

Yes. Every browser still requests /favicon.ico on every domain as its first icon fallback. Modern sites typically provide both favicon.ico and higher-quality SVG or PNG icons via <link rel="icon"> tags — browsers pick the best match.