Bulk Image Resizer
- Free
- No upload
- No watermark
Quick answer
Resize an entire folder to one common width or height in a single pass, with the aspect ratio kept per image and the results handed back as a single ZIP.
What it does
What the bulk image resizer does
A batch of photos rarely shares one aspect ratio — a phone gallery mixes landscape and portrait shots from the same afternoon. Setting a maximum width or a maximum height, rather than a fixed width and height pair, lets every image scale down proportionally to fit that one limit without anything being stretched or letterboxed.
The work is split across several Web Workers, so a folder of eighty photos is not resized one at a time on a single thread while the tab freezes. Each worker decodes, resamples, and re-encodes its own share of the files in parallel, roughly scaling with how many cores your machine can put to work.
When every file is done, Toolvy zips the results client-side and hands you one download. File names are kept from the originals so the batch still matches whatever folder structure or spreadsheet you were tracking them against before you started.
Step by step
How to use it
- 01
Select the folder or files
Choose every image at once — Toolvy reads them all before any processing starts.
- 02
Set a maximum width or height
Enter one number; every image is scaled down to fit it while keeping its own proportions.
- 03
Watch the parallel progress
Multiple Web Workers process files at the same time, and a counter tracks how many are finished.
- 04
Download the ZIP
Grab the single archive once processing completes; original file names are preserved inside it.
Your images never leave your device
Nothing in the folder is transmitted to run this batch — the workers all live inside the browser tab. That is the difference between using this and a cloud batch-resize service when the folder is a wedding shoot still under exclusive licence to the couple, or a set of internal product renders that have not been announced yet. The images stay on the device that opened them.
- No file is ever uploaded to a server
- Works offline after the first visit
- No account, no watermark, no limits
Get better results
Format and quality tips
- 01
Maximum width vs maximum height
Choose maximum width when the images will sit in a fixed-width column, like a blog body or a product grid. Choose maximum height when they will be judged by how tall they are, like a row of thumbnails in a horizontal carousel. Toolvy never resizes past the limit you did not set, so a portrait photo under a width cap can still come out taller than the shortest landscape shot in the same batch.
- 02
Skip images that are already smaller
If a folder mixes high-resolution camera files with a few web-downloaded images already under your target, enlarging the small ones will only soften them. Set the limit to match your largest acceptable size and let the tool leave anything already under it alone where that option is available.
A little more clarity
Frequently asked questions
01How many images can I resize at once?
There is no hard cap from the tool itself, but very large batches are limited by the memory on your device, since every file is held in the browser tab while it processes.
02Does bulk resizing keep the folder structure?
File names are preserved inside the ZIP, but nested subfolders are flattened into one archive level. Rename ahead of time if you rely on folder paths to sort images later.
03Will all my photos come out the exact same size?
No, by design. Only the width or height you cap is shared; the other dimension varies per photo so nothing gets stretched or cropped to force a uniform box.
04Why is bulk resizing faster than doing one image at a time?
Multiple Web Workers run in parallel across your CPU cores, so several images are being decoded and resampled simultaneously instead of queued one after another.
05Can I bulk resize mixed formats like PNG and JPEG together?
Yes. Each file keeps its own format through the resize unless you choose a single output format for the whole batch before starting.
06Does the ZIP get uploaded anywhere before I download it?
No. The archive is assembled in memory in your browser and offered as a direct download; it never touches a server in between.
Guides
Further reading
- Guide6 min readSocial Media Image Sizes: The Cheat SheetThe sizes you actually need, in one table, and the reason a correctly-sized image beats a giant original: every platform re-encodes what you upload, so the pixels you send are never the pixels people see.Read the guide
- Guide6 min readPassport Photo Size GuideThe official sizes for US, UK, EU, India, China, Canada, Australia and Japan photos, converted to pixels at 300 DPI with the arithmetic shown — and a clear line on what a resizing tool can and cannot verify.Read the guide
- Guide6 min readHow to Crop Images Without Losing QualityCropping does not blur anything — it just removes pixels at the edges. What actually costs you quality is re-encoding a JPEG and enlarging the crop afterwards. Here is how to avoid both.Read the guide
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