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

Q: What is an ICO file?

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.

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 tags in HTML.

ICO vs TIFF

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

Convert ICO → TIFF Convert TIFF → 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

TIFF

TIFF Image

Raster & Vector Images

TIFF is a flexible, high-quality image format widely used in publishing, printing, and professional photography. It supports multiple compression methods and color spaces including CMYK.

About TIFF 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.

TIFF Strengths

Lossless by default — no generation loss on successive edits and saves.
Supports any bit depth (1 to 32 bits per channel), any color model, any number of channels.
Extensible tag system means vendor-specific data survives alongside standard tags.
Multi-page containers are perfect for scanned documents, faxes, and DICOM-like stacks.
Industry-standard for archival, museums, scientific imaging, and high-end print prepress.

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.

TIFF Limitations

File sizes are huge compared to JPEG/WebP/AVIF — often 10-30× larger.
Not a web format — no browser displays TIFF natively.
Ambiguous spec areas mean some TIFFs only open correctly in the tool that created them.
Weak animation support — designed for still imagery.

Technical Specifications

Specification	ICO	TIFF
MIME type	image/vnd.microsoft.icon	image/tiff
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+)	—
Extensions	—	.tif, .tiff
Standard	—	TIFF 6.0 (1992); BigTIFF extension for 64-bit offsets
Max file size	—	4 GB (TIFF); 2^64 bytes (BigTIFF)
Compression options	—	None, LZW, Deflate, JPEG, CCITT G3/G4, PackBits, JBIG

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

TIFF

Scanned A4 page (300 dpi, B&W) 100-300 KB
Scanned A4 page (600 dpi, color) 15-40 MB
Print-quality magazine photo 30-150 MB
Satellite GeoTIFF tile 50 MB - 5 GB

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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.