How to Batch Resize Images
Resizing photos one at a time is a time sink nobody needs. A real-estate shoot, a product catalog, or a week of blog photos can mean hundreds of files that all need the same treatment. Batch resizing applies one set of dimensions, format, and quality settings to the entire set in a single pass. Here's the workflow in Re-Sizefy, which processes everything locally in your browser.
The batch workflow
- Decide your target size first. Work backwards from where the images will be shown: 1600px wide for a portfolio gallery, 1200px for blog heroes, 800px for marketplace thumbnails. Resizing to the actual display size is the biggest file-size win you can get.
- Drag the whole folder in. Drop dozens or hundreds of files into the tool at once — drag and drop accepts mixed JPG, PNG, and WebP in one batch.
- Set dimensions and lock the aspect ratio. Enter the target width (or height) and keep the aspect ratio locked so nothing stretches. Mixed portrait and landscape shots in one batch are fine; each scales to fit the same long edge.
- Choose the interpolation. Re-Sizefy's multi-step downsampling shrinks large images in gradual stages rather than one harsh jump, and bicubic interpolation preserves fine detail better than bilinear when the size reduction is large. For big reductions (4000px → 800px), multi-step bicubic is worth it.
- Set format and quality once. Pick the output format (WebP for web delivery) and a quality level — 80 is a reliable starting point for photos. The same settings apply to every file.
- Name and download. Apply a file renaming rule (for example, appending
-1600w) so the batch is distinguishable from your originals, then download everything as one ZIP archive.
Tips for clean batches
- Spot-check before committing. Run 2–3 representative files (one dark, one detailed, one with text) through your settings first. If they look right, run the full batch.
- Keep originals untouched. Never overwrite your source folder. Export to new filenames so you can re-run with different settings later without quality loss.
- Separate by purpose. One batch per target size. Thumbnails and hero images need different settings; mixing them in one run forces a compromise that serves neither.
- Watch the ZIP. Batches of several hundred large photos can produce a heavy ZIP — split into groups of ~100 if your browser feels sluggish.
Common mistakes
The biggest one is upscaling: setting a target size larger than the source. Upscaling invents pixels that were never there and just inflates the file. If a photo is smaller than your target, exclude it or accept its native size. The second mistake is resizing already-resized files — each re-encode loses a little quality, so always batch from the highest-resolution originals you have.
Try it now
Open the free Re-Sizefy batch tool — drop in your folder, set one size, download the ZIP. No sign-up, nothing uploaded.