How to Convert and Resize Images in Bulk
Converting images one at a time is fine for a single file — but when you have a folder of photos to prepare for a website, a batch of screenshots to shrink, or a set of product images to standardize, you want to do them all at once. Here's how to batch-process images for free, without uploading them anywhere.
Why bulk (and why WebP)
Doing images in bulk saves obvious time, and it's also where format choice pays off. Converting to WebPtypically cuts file size 25–35% versus JPG at similar quality — across dozens of images, that's a big speed win for a website.
Convert and resize a whole batch
Use the Bulk Image Converter & Resizer:
- Open Bulk Image Converter and add your images.
- Choose the output format (WebP, JPG, or PNG), quality, and an optional max size.
- Convert them all and download individually — or as one ZIP with Pro.
Everything runs in your browser, so even a large batch of photos never leaves your device.
Just one image?
- Convert a single image's format with the image converter.
- Resize one image to exact dimensions with the image resizer.
- Turn a set of images into a document with Images to PDF.
Tips for web images
- Cap the dimensions — most sites never display images wider than ~1600px, so set a max size to save weight.
- Use WebP for photos and JPG-like content; keep PNG only when you need transparency or crisp text.
- Aim for 70–85% quality — usually indistinguishable from full quality at a fraction of the size.
FAQ
How many images can I process at once?
The free tier processes up to 3 images per batch; OhoTool Pro removes the limit and adds one-click ZIP download.
Are my images uploaded?
No — all conversion and resizing happens locally in your browser using a canvas, so nothing is uploaded.