Skip to content

PNG to WebP converter

PNG → WebP kept the alpha channel in our RGBA sample, but the 1,084 byte PNG grew to 1,320 bytes because the test artwork was tiny.

  • Converted with Image engine · nothing stored
  • Free: 5 conversions a day · 5 MB each
  • Higher limits →

From real runs

What you get — and what changes

  • Alpha channel Kept

    Transparent corners in the RGBA PNG stayed transparent after decoding the WebP output with our image engine.

  • Small flat artwork Changed

    The 96×64 icon-style PNG grew from 1,084 bytes to 1,320 bytes at quality 90 instead of shrinking.

  • PNG text chunks Lost

    The input Comment and Source chunks were not visible in the WebP metadata returned by the API.

  • ICC profile Lost

    The sRGB ICC profile in the test PNG did not appear in the WebP info keys after conversion.

  • 16-bit samples Changed

    A 16-bit grayscale PNG decoded to an 8-bit RGB WebP, so high-bit-depth channel precision was reduced.

  • Pixel dimensions Kept

    The default conversion kept the 96×64 dimensions, while resize options are needed for a new raster size.

Sample conversions

Transparent app badge

Input
A 96×64 RGBA PNG with transparent corners, antialiased shapes, text chunks, and an sRGB profile.
Output
A 1,320 byte WebP in RGBA mode. Alpha survived, but the metadata keys changed to WebP container fields.

16-bit grayscale gradient

Input
A 64×32 16-bit PNG gradient running from black to white, 247 bytes on disk.
Output
An 82 byte WebP read back as RGB. The gradient was compact, but no 16-bit channel depth remained.

A real PNG → WebP run

We converted our PNG sample (20 KB) with Image engine on 2026-10-20. It took 219 ms and produced a 23 KB WebP file, about the same size as the input. The engine raised 1 warning, listed below.

Input · sample.png · 20 KB

1200 × 800 px, 8-bit, colour type 6

Width
1,200
Height
800
Encoding
8-bit, colour type 6

Output · sample.webp · 23 KB

1200 × 800 px, extended VP8X

Width
1,200
Height
800
Encoding
extended VP8X
  • Image metadata stripped from output.

Is your file a scan?

For screenshot PNGs, converting to WebP only changes the image container. Use screenshot-to-text if the screen content needs to become copyable text or structured data.

Options and when to change them

quality
Lower it for photographic PNGs headed to the web; leave it high for logos only if the target accepts the larger output.
width
Set width when exporting one canonical WebP size for a CMS slot or responsive image breakpoint.
height
Set height with width when the receiving layout requires an exact box rather than proportional scaling.
fit
Use contain for padded thumbnails, cover for cropped previews, and fill only for deliberately stretched graphics.

Do it yourself

Pillow 11

bash
from PIL import Image

Image.open("in.png").save("out.webp", format="WEBP", quality=90)

Install WebP-enabled Pillow. High-bit-depth PNGs are decoded before writing and may not stay high precision.

PNG to WebP by API or MCP

The HTTP API and the MCP server run the exact engine this page uses (Image engine); the response carries the same warnings the web converter shows. Check support first with GET /api/v1/pairs?from=png&to=webp.

curl
curl -X POST https://filetypeconverters.com/api/v1/convert \
  -H "Authorization: Bearer $FTC_API_KEY" \
  -F "file=@input.png" -F "from=png" -F "to=webp" \
  -F 'options={"dpi":96}' \
  --output output.webp

Options this engine accepts for PNG → WebP

KeyApplies toTypeDefault
dpiReading PNGnumber96
widthWriting WebPnumber0
heightWriting WebPnumber0
fitWriting WebPcontain · cover · fillcontain
qualityWriting WebPnumber90
backgroundWriting WebPstring#ffffff
stripMetadataWriting WebPbooleantrue
API reference

When this is the wrong conversion

  • Keep PNG for source artwork that carries important text chunks, palette details, or high-bit-depth data.
  • Use AVIF for browsers and apps where smaller photographic output matters more than WebP compatibility.
  • Use PNG → PDF when the goal is an uploadable document page rather than a web image.

PNG to WebP questions

Will transparent PNGs stay transparent as WebP?

Yes for the tested RGBA case. The decoded WebP still had alpha at the transparent corners.

Why did my PNG become larger as WebP?

Very small flat images can grow because WebP has its own container and prediction overhead. Photos are where quality settings usually produce clearer byte savings.

Does PNG → WebP keep 16-bit precision?

No in our API run. A 16-bit grayscale PNG came back from WebP as 8-bit RGB when inspected with our image engine.

Related conversions