Bulk Image Resizer

How to resize images in bulk

1. Select or drop all your photos into the box above. You can pick a whole folder’s worth at once with Ctrl+A (Cmd+A on a Mac) in the file picker.
2. Choose how to resize by: Percentage, Width, or Fit inside width × height.
3. Set the number. Percentage runs from 5% to 200% in steps of 5. Width and height start at 1200 pixels.
4. Optional: type a Max size per file in KB, such as 200. Every file then comes out at or under that size.
5. Pick a format and, for JPG or WebP, a quality (default 90%). The quality slider hides when a KB limit is set, because the tool picks the quality itself.
6. The batch starts on its own and shows “Processing 3 of 40” as it goes. Changing any option runs it again.
7. Click Download all (ZIP), or save single files with their own Download buttons.

The three resize modes, with real numbers

The mode decides what happens to photos of different shapes in the same batch. This matters more than people expect, because a phone shoots landscape and portrait photos at the same pixel count. Here is what each mode does to three typical files:

• Percentage treats every file the same way relative to its own size. Use it when you just want everything smaller, such as 50% to halve the width and height.
• Width gives every image the same width and lets the height follow. Portrait photos end up taller than landscape ones, which can surprise you: at 1200 wide, a portrait photo is 1600 tall.
• Fit inside width × height makes sure no side goes past your box. It’s the safest choice for mixed batches, because both landscape and portrait photos stay within 1200 pixels on their longest side.

The shape of each photo is always kept. Nothing is cropped or stretched in bulk mode.

Worked example: 40 phone photos for a website

Say you have 40 photos from a 12-megapixel phone, some landscape and some portrait, for a product page or blog. Pick Fit inside width × height, keep 1200 × 1200, set Format to WebP and quality to 80%.

Each landscape photo comes out at 1200 × 900 and each portrait at 900 × 1200. That is 1,080,000 pixels per photo instead of 12,000,000, or about 9% of the original pixels. File names show the new size, such as IMG_2041-1200×900.webp, and the ZIP downloads as bulk-image-resizer.zip.

If the page builder or form also has a KB limit per file, type it in Max size per file in KB before you download. For a 150 KB cap, type 150, and each photo is saved at the highest quality that stays at or under 150 KB.

What we measured

We ran a mixed batch of three files through the bulk resizer’s code in Chrome on 19 October 2026: a 3840 × 2525 photo of the Taj Mahal (4.42 MB JPG), a 1200 × 675 website screenshot (430.9 KB PNG) and an 800 × 800 logo (9.3 KB PNG).

Three things stand out. WebP came out about 28% smaller than JPG for the photo and about 41% smaller for the screenshot at the same quality setting. The screenshot was already 1200 wide, so Fit left its pixels alone and only the format change shrank it. And the small logo was enlarged from 800 to 1200 pixels by Fit mode, which is rarely what you want for a logo.

Format and quality settings

For photos, a quality of 80% to 90% is hard to tell apart from the original on a screen. Drop to 70% only if file size matters more than fine detail. PNG files ignore the quality setting, so if a batch of PNG screenshots is still too heavy, switch the format to WebP.

Capping every file at a size in KB

Type a number in Max size per file in KB and every file in the batch is saved at or under it. The tool searches for the highest quality that fits, file by file, so a plain screenshot keeps more quality than a busy photo under the same cap.

• PNG becomes JPG. PNG has no quality setting, so its size can’t be steered. With a KB limit set, PNG files are saved as JPG and transparent areas turn white. Pick WebP in the Format menu to keep transparency.
• Pixels shrink only if they must. If a file is still too big at 5% quality, its width and height drop by 20% at a time until it fits, and its result says “Dimensions reduced to reach the target size.”
• Leave a small margin. The minimum is 5 KB, and the tool counts 1 KB as 1,024 bytes. Some portals count 1,000, so type 1 KB under their limit.

Resize mode and the KB limit work together. Fit inside 1200 × 1200 with a 150 KB cap gives sharper files than a 150 KB cap on full-size photos, because the encoder has fewer pixels to squeeze.

How the ZIP download works

As soon as two or more files finish, a Download all (ZIP) button appears above the results. The ZIP is built in your browser, so it starts without any upload or wait for a server.

• Each file is named after the original plus its new size, so beach.jpg resized to 1200 × 900 becomes beach-1200×900.jpg.
• If two results end up with the same name, the second one gets a number in front, so nothing is overwritten inside the ZIP.
• If one file can’t be read, it shows as an error card with its name and the rest of the batch still finishes.

Each result also shows its new pixel size and file size, so you can spot any odd one before downloading.

Bulk resizing for Indian use cases

• Office and college submissions: event photos, ID scans or project images often need to be under a size limit for email. Fit inside 1600 × 1600 with JPG at 85% is a sensible start, and the files stay readable on any phone.
• Online sellers: product photos for a shop or catalogue look neater when they share one width. Use Width mode for a uniform look, or Fit if you have both tall and wide shots.
• WhatsApp groups and Google Drive: halving 50 photos with Percentage at 50% cuts the pixel count to a quarter, which makes sharing over mobile data quicker.
• Exam forms: these need one photo and one signature with exact pixel sizes as well as KB limits. Use the single image resizer for those, because it sets exact width and height. For a stack of documents that only has a KB cap, the bulk KB limit is quicker.

Tips for a clean batch

• Check for small images first. Width and Fit modes also enlarge files that are smaller than your setting, as the 800 × 600 row in the table shows. Enlarged photos look soft. Remove small files from the batch or use Percentage.
• Convert iPhone HEIC photos first with HEIC to JPG if your browser can’t open them. They will show an error card otherwise.
• Split very large batches. Every photo is held in your device’s memory while the batch runs. Hundreds of 12-megapixel photos can slow down an older phone, so do them in a few rounds.
• Crop first when shape matters. Bulk mode never trims. If every image must be square, crop each one with the crop tool or use a preset ratio in the single resizer.

Limitations

• KB limit is a maximum. It never pads a file up to a portal’s minimum size. For that, raise the width or remove the limit.
• No cropping or fixed ratio. Every image keeps its own shape.
• No rename pattern. Files keep their original name plus the new size.
• Metadata is dropped. EXIF details such as camera model and location are not copied to the new files.
• Animated GIFs become a single still frame.
• Very large outputs may fail on phones. At 200%, a 4000 × 3000 photo becomes 8000 × 6000, which is beyond what iPhones and iPads allow in the browser.

Key facts

• Most browsers allow canvas images above 10,000 × 10,000 pixels, but iOS devices limit canvas size to 4,096 × 4,096 pixels. (MDN (opens in new tab))
• Halving width and height leaves a quarter of the pixels: 4000 × 3000 is 12,000,000 pixels and 2000 × 1500 is 3,000,000.
• JPG has no transparency channel, so transparent PNG areas become a solid colour when saved as JPG. This tool uses white.