Picovert

How to Batch Resize Images Free: 5 Methods for Bulk Resizing

By Picovert Team2026-01-225 min read

Need to resize 50 product photos to 1000×1000px? Preparing a batch of portraits for a website? Batch resizing saves hours compared to processing images one at a time. This guide covers five free methods — from browser-based tools to command-line power tools — so you can pick the approach that fits your workflow.

Why batch resize images?

  • Uploading to a website or CMS — most content management systems expect images at consistent dimensions. A folder of photos from different cameras or phones will have wildly different sizes. Batch resizing normalizes them before upload.
  • Sharing via email or Google Drive — full-resolution photos from a modern smartphone are 4–12 MB each. Batch resizing to 1500px wide reduces a 20-photo folder from 200 MB to under 10 MB without visible quality loss.
  • E-commerce product images — platforms like Amazon require exact pixel dimensions (1000×1000px minimum, 2000×2000px recommended). Batch processing ensures every product image meets requirements in one pass.
  • Social media bulk preparation — scheduling tools work best when all images are already sized for the target platform. Resizing in bulk before scheduling saves repetitive manual work.

Method 1: Online tool — fastest, no install

Picovert's Image Resizer supports multiple file uploads and processes everything in your browser — no files are sent to a server.

  1. Open the Image Resizer.
  2. Click or drag to upload all your images at once. Supports JPG, PNG, WebP, AVIF, GIF, and HEIC.
  3. Set your target width and height in pixels, or enter a percentage to scale proportionally. Enable "Maintain aspect ratio" to avoid distortion.
  4. Click Resize. All images are processed simultaneously and downloaded as a ZIP file.

This is the fastest option for occasional batch jobs or when you are on a shared computer. After resizing, you can also run the images through the Image Compressor to reduce file size further before uploading.

Method 2: Windows — Image Resizer PowerToy

Microsoft's free PowerToys suite includes an Image Resizer that integrates directly into Windows Explorer.

  1. Install PowerToys: winget install Microsoft.PowerToys (or download from the Microsoft Store).
  2. Open File Explorer and select all the images you want to resize. You can use Ctrl+A to select all files in a folder.
  3. Right-click the selection and choose Resize pictures.
  4. Pick a preset size (Small, Medium, Large, Phone) or select Custom and enter exact pixel dimensions.
  5. Choose whether to resize the originals or make copies (copies are recommended). Click Resize.

Resized copies are placed in the same folder with the size appended to the filename (e.g., photo (Small).jpg). Originals are always preserved when using the copy option.

Method 3: Mac — Automator

Automator is built into macOS and requires no installation. It can resize an entire folder of images in seconds.

  1. Open Automator (search in Spotlight with Cmd+Space).
  2. Click New Document and choose Workflow.
  3. In the search bar on the left, search for Scale Images and drag it into the workflow area.
  4. When prompted, choose Add a Copy Finder Items action to preserve originals — this adds a copy step before resizing so your original files are not overwritten.
  5. Set the pixel width in the Scale Images action. Check Don't scale images up to prevent small images from being enlarged.
  6. Drag your image folder onto the workflow and click Run.

You can also save the workflow as an application and drop folders onto it directly from the Finder in the future — useful if you resize images regularly.

Method 4: Photoshop — Image Processor script

Photoshop's built-in Image Processor script handles batch resizing without requiring any actions or macros.

  1. Go to File → Scripts → Image Processor.
  2. Under Select the images to process, click Select Folder and choose your source folder. Check Include All Sub-Folders if needed.
  3. Under Select location to save processed images, choose a destination folder (recommended) or save in the same location.
  4. Under File Type, check Save as JPEG and set quality (8–10 is recommended for web). You can also save as PSD or TIFF.
  5. Check Resize to Fit and enter your target width and height. Photoshop preserves aspect ratio and will not exceed either dimension.
  6. Click Run. Photoshop processes all images non-destructively — originals are never modified.

Method 5: ImageMagick — command line (most powerful)

ImageMagick is free, open-source, and handles thousands of images in seconds. It is ideal for automated pipelines or when you need precise control over output.

Install ImageMagick: brew install imagemagick on Mac, winget install ImageMagick.Q16 on Windows, or sudo apt install imagemagick on Linux.

Common resize commands:

  • Resize all JPGs in a folder to 1200px wide (preserves aspect ratio):
    mogrify -resize 1200x *.jpg
  • Resize to fit within a 1200×1200px box (neither dimension exceeds 1200px):
    mogrify -resize 1200x1200 *.jpg
  • Resize and convert to WebP at the same time:
    mogrify -resize 1200x -format webp *.jpg
  • Resize to output copies without modifying originals (saves to an output/ folder):
    mkdir output && convert '*.jpg[1200x>]' -set filename:base "%[basename]" output/%[filename:base].jpg

The mogrify command modifies files in place — always work on a copy of your images or use the convert command with an output directory when the originals must be preserved.

Tips for batch resizing

  • Always work on copies — batch operations process dozens or hundreds of files and are difficult to undo. Keep originals in a separate folder.
  • Resize to the dimensions you actually need — resizing to 2000px when the display size is 800px wastes storage and bandwidth. Match the resize target to the actual use case.
  • Combine resize with compression for web — resizing reduces file size significantly, but running the resized images through a compressor afterward can reduce file size by another 40–70% without visible quality loss. This two-step approach gives the smallest files.
  • Check aspect ratio handling — some tools crop to fill exact dimensions, others fit within the dimensions while preserving the ratio. Verify your tool's behavior before processing a large batch.