PNG to ICO 256x256 Converter

Some programs want exactly one thing: an .ico whose image is 256 × 256 px. This page is set to that single size, so the PNG you upload becomes one large, transparent Windows icon instead of a stack of small favicon sizes.

or drop JPG, JPEG, JPE … files here ·

Max 95 MB per file· Up to 20 files· Deleted after 30 minutes

Output

Convert to

Files are processed on our servers and deleted after 30 minutes.

How to use this tool

1
Upload a square PNG
Use artwork that is 256 × 256 px or larger, with a transparent background if the icon should float on the desktop. Up to 20 PNGs per batch.
2
Leave Icon sizes on 256 px
Icon sizes is preset to 256 px. Switch to All sizes (16–256) only if the same file must also serve as a browser favicon.
3
Convert and download
Press Convert to ICO. Each PNG returns as its own .ico file, or as one ZIP when you converted several.

Answer

How do I get a 256 × 256 ICO from a PNG?

Upload a square PNG of at least 256 px and press Convert to ICO. The page writes one 256 × 256 image into the .ico with its transparency, which is the size Windows uses for Extra large icons.

Why 256 × 256 px is the size Windows asks for

Until Windows Vista shipped in 2007, desktop icons topped out at 48 × 48 px. Vista added the 256 × 256 size so that icons could scale smoothly in Explorer's zoomable views, and every release since, including Windows 10 and 11, uses it for the largest view. If an icon file has no 256 px entry, Windows enlarges a smaller one and it looks soft.

The scale below shows which image Explorer picks in each view at 100% display scaling. Only Extra large icons uses the full 256 px image directly; the others are reduced from it when a file holds only that one size.

Recommended

16 px48 px96 px256 px

16 px
Small icons, List and Details views
48 px
Medium icons view
96 px
Large icons view
256 px
Extra large icons and installer artwork

PNG-compressed entries inside a 256 px ICO

PNG

Portable Network Graphics

PNG is a lossless raster format published in 1996 by the PNG Development Group and later standardised by the W3C and ISO. It keeps every pixel exactly, supports full alpha transparency and handles text, sharp edges and flat colours without artefacts. That precision makes it ideal for screenshots, logos, icons and interface graphics. The trade-off is size: photographs saved as PNG are often several times larger than the same photo as JPEG or WebP. All browsers, operating systems and editors open PNG files.

Compression: Lossless
Transparency: Yes
Animation: No
Introduced: 1996 · PNG Development Group

PNG converter

ICO

Windows icon

ICO is the Microsoft icon format used for Windows program icons and website favicons. One .ico file can contain several images at different sizes, such as 16×16, 32×32, 48×48 and 256×256 pixels, so the system can pick the best fit. Each image can be stored as a bitmap or as PNG data and supports full alpha transparency. ICO is not meant for photos or large artwork. Browsers, Windows and most icon editors can read it.

Compression: Lossless
Transparency: Yes
Animation: No
Introduced: Microsoft

ICO converter

A PNG becomes a single 256 × 256 ICO when an installer, launcher or Explorer's largest view needs one high-resolution icon image, rather than the small multi-size bundle a favicon wants.

PNG-compressed icon entryVista icon · PNG icon image: An image inside an .ico that is stored as a complete PNG file instead of an uncompressed bitmap. Introduced with Windows Vista for the 256 px size, it keeps a full alpha channel while shrinking an entry that would otherwise take about 256 KB of raw pixels.

One 256 px image or a multi-size ICO

A raw 256 × 256 image with 32-bit color takes 262,144 bytes before compression, which is why large icons are normally stored as PNG data inside the ICO. Small sizes stay tiny either way, so a single-size file saves little space; the real reason to choose it is that something asks for exactly one image, or you want Windows to do the downscaling.

If you care how the icon looks at 16 or 32 px, a multi-size file is better: designers often simplify the artwork for small sizes, dropping thin outlines and text, and a multi-size PNG to ICO file lets each view pick its own image. Starting from a vector logo? SVG to ICO renders each size from the paths.

Prepare the PNG as a square with a transparent background and roughly 8 to 16 px of empty margin. Non-square artwork should be cut to shape first with crop image, because icon slots are square.

256 × 256 ICO questions

When should an ICO hold only the 256 px image?

When the tool that consumes it asks for that, as some installer builders, game launchers and theme packs do, or when you set a folder or shortcut icon that is mostly seen in Large and Extra large views. For a website favicon, a multi-size file from PNG to ICO is the better choice.

Will Windows scale a 256 px icon down for small views?

Yes. Explorer resamples the one image it has, so the icon still appears in Small icons and Details views. Fine lines and text can turn muddy at 16 px, which is the trade-off of a single-size file.

Why does an icon editor list my 256 px icon as 0 × 0?

The ICO directory stores width and height in one byte each, so the largest value it can write is 255. By convention a 0 means 256. Some older viewers print the raw byte instead of interpreting it.

Does a 256 × 256 ICO work on Windows XP?

Usually not. Windows XP predates the 256 px size and cannot decode PNG-compressed icon images, so such an entry may show as blank. Every Windows version since Vista reads it.

Is the transparent background of my PNG kept?

Yes. ICO supports full alpha transparency, and soft shadows and anti-aliased edges carry over. Check the result on a dark desktop wallpaper, where stray light pixels around the edge show up first.

What does electron-builder need for a Windows app icon?

Its documentation asks for an icon.ico of at least 256 × 256 px, or a 256 px PNG that it converts itself. A single-size 256 px ICO from this page meets that minimum.