Batch Image Resizer

Resize multiple images at once to specific dimensions, percentages, or max widths/heights.

Tested tool guide Tested browser tools Checked August 16, 2026

What Batch Image Resizer does, with a checked example

Give one sizing instruction to a group of image files instead of repeating the same resize by hand. Batch Image Resizer accepts multiple images and applies explicit pixel dimensions, a percentage scale, or maximum width and height constraints. The files are handled in the browser and are not uploaded. The common misunderstanding is that a maximum-size setting makes every output identical. A maximum defines a boundary, so images with different proportions can finish at different widths or heights.

Worked example

A concrete input and expected output from the current implementation.

Input

Image 1: 1200 x 800 px
Image 2: 640 x 480 px
Mode: percentage
Scale: 50%

Expected output

Two resized images: Image 1 is 600 x 400 px; Image 2 is 320 x 240 px.

A 50 percent scale multiplies both dimensions of each source by 0.5. The calculation is performed separately for every image, preserving the 3:2 and 4:3 proportions in this example.

How the result is produced

Choosing the sizing rule

Specific dimensions express a fixed pixel target. Percentage mode scales each source relative to its own width and height, so a mixed batch remains mixed in absolute size. Maximum width and height describe a boundary within which images must fit. Choose according to whether you need a fixed target, proportional scaling, or a size ceiling.

Applying the batch instruction

The same selected sizing instruction is evaluated for every source image. Results therefore depend on each file's original pixel dimensions and proportions. Processing stays on the device in the browser, which avoids uploading the selected images. Very large source files or batches can still be constrained by the browser and the device resources available to it.

Good uses

Preparing a product-image folder so every listing image fits a storefront's maximum width and height without resizing files individually.
Creating 50 percent copies of a mixed set of photographs while retaining the relative proportions of each original image.
Converting a collection of avatars, thumbnails, or presentation graphics to requested pixel dimensions before importing them into another system.

Limits and checks

Maximum dimensions are not exact dimensions. A portrait and a landscape image can both fit within the same width-height boundary while ending with different dimension pairs.
Percentage scaling starts from each source file. At 50 percent, a 4000-pixel-wide photograph and a 1000-pixel-wide graphic become 2000 and 500 pixels wide, not a common width.
Do not assume that changing pixel dimensions preserves animation, metadata, color profiles, filenames, or every source format. Inspect a representative output before processing an important batch.

Common questions

Will every resized image have identical dimensions?

No, not when you use percentage scaling or maximum width and height. Those rules begin with each file's own dimensions and proportions, so outputs can differ. Choose specific dimensions when a fixed width-height pair is required. Test an image whose aspect ratio differs from that target and inspect its appearance before processing the full batch.

Does resizing guarantee a smaller file in KB or MB?

No. Resizing changes pixel dimensions, while byte size also depends on the image format, encoding, visual detail, transparency, and metadata. Reducing dimensions often lowers storage requirements, but there is no fixed conversion from pixels to bytes. If another service imposes a file-size limit, measure the actual output files rather than inferring their sizes.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.