How to Convert JPG Images to JPEG in Bulk

For files that already contain JPEG image data, converting .jpg to .jpeg usually means renaming the filename extension. The bytes do not change, so there is no quality loss and no image conversion step. If the files contain another format, or you need resizing, color-profile changes, metadata edits, or a new JPEG quality setting, use an image converter and accept that JPEG encoding is lossy.

ImageMagick lists JPG and JPEG as JPEG filenames and uses the output extension to select an output format. Its documentation also describes magick as an image conversion and processing tool (format notes; command-line processing).

Decide whether you need a rename or a conversion

Your goal	Use	Do the image bytes change?
Make software accept `.jpeg` instead of `.jpg`	Bulk rename	No
Resize, rotate, sharpen, change color profile, or remove metadata	Image conversion or processing	Usually yes
Convert PNG, WebP, TIFF, or another format to JPEG	Image conversion	Yes
Set a different JPEG quality level	Re-encode with a converter	Yes

A filename change does not turn a PNG into a JPEG. Conversely, re-encoding an already-JPEG file does not improve it; repeated JPEG encoding can reduce quality. JPEG also does not support transparency (ImageMagick JPEG format notes).

A rename changes the filename; re-encoding changes the image data.

Before changing hundreds of files

Copy a small sample into a test directory.
Check that the files are actually JPEGs. On macOS or Linux, run file sample.jpg. With ImageMagick, run magick identify sample.jpg.
Choose a separate output folder if you need an easy rollback.
Decide how to handle a name collision such as both photo.jpg and photo.jpeg already existing.
Keep the originals until you have opened and verified the results.

Replace the suffix; do not append a second suffix. A correct result is photo.jpeg, not photo.jpg.jpeg. Decide whether uppercase names such as PHOTO.JPG should also be changed.

Bulk rename JPG files on macOS or Linux

Bash: copy into a new folder

This script handles spaces and other ordinary characters safely, preserves the original files, and changes both lowercase and uppercase extensions. Run it from the directory containing the images.

#!/usr/bin/env bash
set -euo pipefail

src="."
dst="./jpeg-output"
mkdir -p "$dst"

find "$src" -maxdepth 1 -type f \( -iname '*.jpg' -o -iname '*.jpeg' \) -print0 |
while IFS= read -r -d '' file; do
  name=${file##*/}
  stem=${name%.*}
  target="$dst/$stem.jpeg"

  if [[ -e "$target" ]]; then
    printf 'Skipping existing file: %s\n' "$target" >&2
    continue
  fi

  cp -- "$file" "$target"
done

If you only want .jpg files, remove the -o -iname '*.jpeg' part. If your files are in nested directories, remove -maxdepth 1, but plan how to preserve directory structure and avoid two different folders producing the same basename.

Bash: rename in place after a dry run

First print the proposed changes:

find . -maxdepth 1 -type f -iname '*.jpg' -print0 |
while IFS= read -r -d '' file; do
  name=${file##*/}
  printf '%s -> %s\n' "$name" "${name%.*}.jpeg"
done

After reviewing the list, rename only files whose destination does not exist:

find . -maxdepth 1 -type f -iname '*.jpg' -print0 |
while IFS= read -r -d '' file; do
  dir=${file%/*}
  [[ "$dir" == "$file" ]] && dir="."
  name=${file##*/}
  target="$dir/${name%.*}.jpeg"

  if [[ -e "$target" ]]; then
    printf 'Skipping existing file: %s\n' "$target" >&2
  else
    mv -- "$file" "$target"
  fi
done

This is a filename operation. It does not decode or re-encode the image.

Bulk rename JPG files on Windows PowerShell

Run this in the folder containing the images. The first command previews the changes; the second performs them while skipping collisions.

Get-ChildItem -File | Where-Object { $_.Extension -ieq '.jpg' } |
  ForEach-Object {
    "$($_.Name) -> $($_.BaseName).jpeg"
  }

Get-ChildItem -File | Where-Object { $_.Extension -ieq '.jpg' } |
  ForEach-Object {
    $target = Join-Path $_.DirectoryName ($_.BaseName + '.jpeg')
    if (Test-Path -LiteralPath $target) {
      Write-Warning "Skipping existing file: $target"
    } else {
      Rename-Item -LiteralPath $_.FullName -NewName ($_.BaseName + '.jpeg')
    }
  }

To include .JPG, -ieq already provides case-insensitive matching. To copy into another folder instead, create the destination directory and use Copy-Item with a constructed target path.

Bulk rename with Python

Python is useful when the rename is part of a larger pipeline. This script copies files to jpeg-output, preserves the originals, handles spaces, and refuses to overwrite an existing destination.

from pathlib import Path
import shutil

source = Path('.')
destination = source / 'jpeg-output'
destination.mkdir(exist_ok=True)

for path in source.iterdir():
    if not path.is_file() or path.suffix.lower() != '.jpg':
        continue

    target = destination / f'{path.stem}.jpeg'
    if target.exists():
        print(f'Skipping existing file: {target}')
        continue

    shutil.copy2(path, target)
    print(f'{path.name} -> {target.name}')

copy2 copies the file and attempts to retain filesystem metadata. It does not inspect or re-encode the image.

When you really need to re-encode

Use conversion when the underlying data must change. Examples include PNG-to-JPEG conversion, resizing, flattening transparency, changing an embedded color profile, stripping metadata, or selecting a new JPEG quality level.

ImageMagick command line

Install ImageMagick from its official site, then convert a single file:

magick input.png -background white -alpha remove -alpha off output.jpeg

For a directory of JPG files that must be rewritten as JPEG data, write to a separate directory:

mkdir -p reencoded
for file in ./*.jpg; do
  [ -e "$file" ] || continue
  base=${file##*/}
  magick "$file" -quality 85 "reencoded/${base%.*}.jpeg"
done

The -quality value is an ImageMagick setting; test representative images because the visual result and file size depend on image content. Never assume that a new extension alone changes the format.

macOS Preview

Adobe’s macOS guide describes a graphical batch-export workflow: select multiple images in Finder, open them in Preview, select all files in the sidebar, choose File > Export Selected Images, then choose a destination and format (Adobe’s Preview workflow). Export creates newly encoded files, so use it when you need conversion or processing. Menu labels can vary by macOS release.

Photoshop Image Processor

For broader batch work, Photoshop provides File > Scripts > Image Processor. Adobe documents conversion to JPEG, PSD, or TIFF, resizing, color-profile handling, unique output names, copyright metadata, and a JPEG quality control from 0 to 12 (Adobe Image Processor documentation). That quality scale belongs to Photoshop’s interface and is not a universal JPEG-quality standard.

Verification checklist

Confirm every output ends in exactly .jpeg.
Open several files from the beginning, middle, and end of the batch.
Check dimensions, orientation, and transparency expectations.
Compare file sizes if you re-encoded; a large change may indicate a quality or color-profile setting.
Run file output.jpeg or magick identify output.jpeg to inspect the actual format.
Keep the source folder until the output has been backed up.

Common errors and fixes

Error or symptom	Cause	Fix
`photo.jpg.jpeg`	The new extension was appended.	Replace the final suffix with `${name%.*}.jpeg`, `$($_.BaseName).jpeg`, or `path.stem + '.jpeg'`.
Files with spaces fail	The shell split an unquoted path.	Use null-delimited `find -print0`, quoted variables, or PowerShell’s `-LiteralPath`.
Existing files are overwritten	The destination was not checked.	Preview first and skip or explicitly version collisions.
The file still contains PNG data	Only the name changed.	Use ImageMagick or another converter to re-encode it.
Transparent areas become black or unexpected	JPEG has no transparency.	Flatten onto an intentional background before conversion, or keep PNG.
Images look softer after processing	JPEG was decoded and encoded again.	Use a higher quality setting, keep the originals, and avoid unnecessary generations.
Some files are skipped	They may use uppercase extensions, hidden suffixes, or a different format.	Use case-insensitive matching and inspect file signatures with `file` or `identify`.
Command works in one shell but not another	Bash, PowerShell, and Command Prompt use different syntax.	Run the script in its intended shell and test on copied files first.

Performance, reliability, and cost

A pure rename or copy is limited mainly by filesystem speed and requires no image decoding. Re-encoding is CPU-intensive, reads and writes every pixel, and can create large temporary storage requirements. Process in batches when the folder is very large, write to a different volume only when necessary, and avoid running multiple workers against the same destination names.

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For reliable automation, make the operation idempotent: skip an output that already exists, record failures, and rerun only failed files. A separate output directory gives you a straightforward rollback. The free command-line tools described here have no per-image API charge; paid software such as Photoshop may be useful when its editing features justify it.

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cURL

curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webp

Python

import requests
r = requests.get("https://api.screenshotneo.com/v1/shot", params={"access_key": "YOUR_API_KEY", "url": "https://stripe.com"}, timeout=90)
open("shot.webp", "wb").write(r.content)

Node.js

const q = new URLSearchParams({ access_key: 'YOUR_API_KEY', url: 'https://stripe.com' }); const res = await fetch(`https://api.screenshotneo.com/v1/shot?${q}`);

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FAQ

Are JPG and JPEG different formats?

No. They are common extension spellings for JPEG image data. The extension change alone does not alter the file.

Can I rename files without installing software?

Yes. Finder, File Explorer, Bash, PowerShell, and Python can rename files. Use an image converter only when the bytes must change.

Will renaming improve image quality?

No. Renaming leaves the bytes unchanged. Re-encoding can reduce quality because JPEG uses lossy compression.

Should I convert PNG to JPEG?

Only when JPEG’s smaller photographic files suit your use case. Plan for lost transparency and choose a background before encoding.

How do I undo a bulk rename?

Rename the final .jpeg suffix back to .jpg, or restore the originals from the backup or source directory. This works because the rename did not change image bytes.