Why this comparison is simple
Preview on Mac, Paint (or Photos) on Windows, and similar built-in tools aren't competing products — they're general-purpose image viewers with a resize dialog bolted on, built for opening and editing one file at a time. Comparing a batch tool to a one-file-at-a-time workflow isn't really a contest between two products; it's a description of what changes once "resize a photo" turns into "resize forty photos."
Side-by-side
| Resizing one at a time (Preview / Paint) | Bulk Image Resizer | |
|---|---|---|
| Steps to resize 40 images | Open, resize, save, close — repeated 40 times | Select the folder once, pick your sizes, and process the whole batch in one run |
| Generating several sizes from the same photo | Resize and re-save once per target size, per image — a thumbnail and a full-size version means doing it twice per file | Pick multiple sizes up front; every image in the batch is resized to all of them in one pass |
| Consistency across a batch | Depends on typing the same dimensions correctly every time — easy to end up with slightly different sizes by mistake | The same preset or custom size is applied identically to every image in the batch |
| File naming across the batch | Whatever "Save As" or "Save a Copy" defaults to, decided one file at a time | Automatic, consistent batch naming with width/height/index placeholders |
| Smart presets for common targets | None — you look up and type exact pixel dimensions yourself each time | Built-in presets for web, icon, and social-platform sizes, plus custom dimensions |
Where resizing one at a time is still fine
If you only need to resize one or two photos — a single profile picture or one attachment — opening Preview or Paint and resizing it directly is still the fastest option. Installing and opening an extension for a single file is more steps, not fewer. This comparison is about the point where "resize a photo" turns into "resize a folder of them": product shots, a batch from a photo shoot, or any set of images you'd otherwise be resizing one at a time, repeatedly.
The honest takeaway: for one or two images, just use Preview or Paint — that's what they're built for. Once you're resizing more than a handful, or you need the same photo set in multiple sizes, batching it through one pass removes the repetition, keeps every output consistent, and is where a dedicated batch tool like Bulk Image Resizer actually earns the extra step of installing it.
For exactly how batching and presets work, see the step-by-step guide. For privacy and data-handling questions, check the FAQ, or read why local, browser-based processing differs from upload-based resize tools. Prefer a different comparison? See how Bulk Image Resizer stacks up against another batch-resizing extension.