Convert JPG to WebP on Mac

No. macOS reads WebP, so you can open and even convert WebP to other formats. Writing it is the missing piece. We ran this on macOS 27.0.1:

sips -s format webp photo.jpg --out photo.webp
Error: Can't write format: org.webmproject.webp

Preview’s Export list has no WebP either. You need a separate tool. The reverse direction is easy and is covered in WebP to JPG on Mac.

Google’s cwebp is the reference command line tool. Install it with Homebrew, then run:

brew install webp

cwebp -q 80 photo.jpg -o photo.webp

# a whole folder
for f in *.jpg; do cwebp -q 80 "$f" -o "${f%.jpg}.webp"; done

-q runs from 0 to 100. Higher means better quality and a bigger file. Version 1.6.0 was used here.

We measured one 2000 × 2000 JPEG saved at quality 85 (447,047 bytes). It is a smooth wallpaper image, which WebP handles especially well, so a busy photograph will save less.

Two lessons. Quality settings are not comparable between formats, so judge by eye, not by the number. And lossless WebP made from a JPEG is bigger than the JPEG, because it faithfully stores every artifact the JPEG already has. Use lossy.

Not by default with cwebp. Our source JPEG carried a Display P3 profile. exiftool found no profile in the WebP written with default options. Without it, browsers treat the pixels as sRGB, and saturated colors can look flatter. For web photos that is usually fine. If color accuracy matters, add -metadata icc to the command, or keep the JPEG. We checked: with that flag exiftool reported Display P3 in the WebP, and the file grew from 71,968 to 72,530 bytes. The flag -metadata all also keeps EXIF, which can include GPS, so avoid it on photos you plan to publish; our EXIF removal guide explains why.

Dimensions matter more than format. Shrinking the picture to the size it is displayed at saves more than any format change. cwebp can do both at once, with 0 meaning “keep the aspect ratio”:

cwebp -q 80 -resize 1000 0 photo.jpg -o photo-1000.webp

On our 2000 × 2000 test image that produced a 1000 × 1000 WebP of 30,452 bytes, less than half of the 71,968 byte full-size version. Pick the width from the largest size the image appears on your page, then double it only if you serve high-density screens.

For a website, yes in most cases: every current browser displays it, and the files are smaller. For email attachments, printing, or uploads to sites that only accept JPG, stay with JPG. Many forms still reject WebP. For the newest and smallest option, see AVIF on Mac. Our image optimization and Core Web Vitals post covers what moves page speed.

For one image, cwebp is free and gives you exact control over every flag. If you already live in Terminal, a loop is faster than any app. Smol is not the fastest tool.

Smol is for people who do not want Homebrew: drop a mixed folder of JPG, PNG and HEIC files in, set the output format to WebP, and get copies beside the originals. By default Smol strips metadata, resizes images to fit 2000 × 2000 pixels unless you change it, and keeps originals. Nothing is uploaded. Quality is set on the compress operation. Smol is $29, once, for one Mac. The best image converter for Mac compares the alternatives, and PNG to WebP covers the other common source.