A batch script that converts all .jpg images in a folder to .webp at 100% quality. Just place it in the folder and double-click. Only works if you have cwebp installed: https://developers.google.com/speed/webp/docs/precompiled

jpg2webp-mass-converter.cmd

@echo off

rem Set the number of files to be converted
for /f "delims=" %%i in ('dir /b /a-d /s *.jpg ^| find /c /v ""') do set "numFiles=%%i"

echo Converting %numFiles% file(s)...

rem Convert each .jpg file in the current directory to .webp
setlocal enabledelayedexpansion
set cnt=0
for /f "delims=" %%i in ('dir /b /a-d /s *.jpg') do (
  cwebp -quiet -q 100 "%%i" -o "%%~dpni.webp"
  set /a cnt+=1
  set progress=!cnt!
  set /a progress=!progress! * 100 / %numFiles%
  echo !progress!%% converted
)
endlocal

echo Done!
pause