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pdfconversionapi

WebP to ICO API

POST a WebP to /v2/convert/webp/to/ico and get an icon file with one 32-bit image of up to 256 × 256, stored as PNG. Transparency from the WebP is kept, including anti-aliased edges; ImageWidth picks the icon size.

Endpoint
POST /v2/convert/webp/to/ico
Accepts
webp
Sample timing
4 ms median of 5 runsHow we measure
Request size
Up to 10 MB on the Free plan or 100 MB on paid plans, all files together

Request and response

Every sample below ran against the API before this page was published. Set PDFCONVERSIONAPI_KEY to your key and run it as is.

curl -sS -X POST \
  https://api.pdfconversionapi.com/v2/convert/webp/to/ico \
  -H "Authorization: Bearer $PDFCONVERSIONAPI_KEY" \
  -F File=@guest-badge.webp \
  --form-string ImageWidth=128 \
  -o response.json

# FileData is base64. Save the first file in converted/,
# or print the JSON error.
if jq -e '.Files' response.json > /dev/null; then
  mkdir -p converted
  name=$(jq -r '.Files[0].FileName' response.json)
  jq -r '.Files[0].FileData' response.json \
    | base64 --decode > "converted/$name"
else
  cat response.json
fi
200 OK4 ms median1 file, 15 KB
{
  "ConversionCost": 1,
  "ConversionTime": 0.004,
  "Files": [
    {
      "FileName": "guest-badge.ico",
      "FileExt": "ico",
      "FileSize": 15255,
      "FileData": "AAABAAEAgFMAAAAAIACBOwAA…"
    }
  ]
}

Response from our test run on 2026-11-03. ConversionTime shows the median of 5 runs. FileData is shortened here; the real response carries the whole file as base64.

The sample, converted

The same file the code sends. Download the input and the output and compare them yourself.

First page of guest-badge.ico, rendered by the API
Input
guest-badge.webp (9.4 KB)
Output
guest-badge.ico (15 KB)
Source
A guest pass for a made-up trade show that we drew for this page, saved as a lossy WebP with a transparent background and a soft shadow. (CC0-1.0). How it was made
Made by
2026-11-04, API build 9eeeb0640aba

Parameters

Send these as form fields next to the file. Names are case-insensitive. If you set one of the documented options below that we don't support yet, the request fails with a 400 that names it instead of returning a file made without it.

ParameterWhat it does
ImageWidthintegerIcon width. The sample asks for 128 and gets 128 × 83; 32 gave 32 × 21 in 1,526 bytes. Anything above 256 is capped.Values: 1–20000
ImageHeightintegerIcon height; together with ImageWidth the badge is fitted inside the box, so 64 × 64 gave 64 × 42.Values: 1–20000
ScaleProportionsboolean, default truefalse with a 64 × 64 box made a square, squashed 64 × 64 icon.
ScaleIfLargerboolean, default falsetrue skips enlarging WebPs that are already smaller than the box.
ScaleImageboolean, default truefalse with 64 × 64 cut the badge's top-left corner out at full scale instead of shrinking it.
ColorSpaceenum, default defaultgray gave a 38,492-byte gray icon at 256 px, alpha kept. monochrome leaves only black and white even after the fit, also with the alpha kept (6,213 bytes at 256 px). cmyk returns 400.Values: default, rgb, gray, monochrome
FileNamestringName for the .ico; guest-badge.ico unless set.
StoreFileboolean, default falsetrue makes the API store the icon for 3 hours and answer with its URL.

What carries over, and what doesn't

Kept

  • Transparency, partial included: the 128 × 83 icon has 253 fully clear pixels and 1,768 partly clear ones along the rounded corners and shadow.
  • Color depth: 32 bits per pixel, stored as a PNG inside the ICO (15,233 of 15,255 bytes).
  • The badge's proportions when you set one side: 400 × 260 became 128 × 83.
  • The heading and GUEST PASS lettering, still readable at 128 px wide.
  • EXIF orientation: a 300 × 200 WebP tagged 6 was stood upright before fitting, giving a 171 × 256 icon.

Lost or not yet supported

  • Small detail: the QR code no longer decoded at 128 × 83.
  • Sizes above 256 pixels: with no options the icon is 256 × 166.
  • Every size but one, and every frame but the first of an animated WebP.
  • EXIF, XMP and ICC data from the WebP.

Limits

  • One WebP per request; one image per .ico, at most 256 × 256.
  • Requests up to 10 MB on the Free plan or 100 MB on paid plans, all files and fields together.
  • The WebP may have up to 100,000,000 pixels; above that the answer is 413.
  • 120 seconds per conversion, then 504.

Where teams use it

App and shortcut icons from web artwork

Logos and badges published as transparent WebP can become .ico files for a Windows shortcut, an installer or a desktop app, with clean edges on any background.

Favicons in one request per size

Request 16, 32 and 48 pixel versions one by one with ImageWidth. Each .ico holds one image, so combine them yourself if you need a multi-size file.

Questions

Does the icon keep the WebP's transparency?

Yes, partial alpha included. The 128 × 83 sample icon has 253 clear pixels and 1,768 partly clear ones, with alpha from 1 to 254 after scaling.

What size is the icon if I don't set one?

The WebP is fitted inside 256 × 256 with its proportions kept. The 400 × 260 badge became 256 × 166 (42,864 bytes).

Can one .ico contain 16, 32 and 48 pixel versions?

No. Each response holds a single image, so make one request per size with ImageWidth.

Can I make a square icon from a wide image?

Set ImageWidth and ImageHeight to the same value with ScaleProportions=false to stretch it, or with ScaleImage=false to crop the top-left square. Fitted normally, a 64 × 64 box gives 64 × 42.

Convert your first WebP file in a minute.