Image Resizer

Resize JPEG, PNG and WebP images in your browser by pixel dimensions or percentage, keep the aspect ratio, and download the new file — nothing is uploaded.

Runs 100% in your browser — nothing you enter leaves your device.

Drop images here or click to browse
JPEG, PNG, WebP, GIF or BMP · up to 20 files, 30 MB each · resized on this device, never uploaded
50% halves each side (a quarter of the pixels). Above 100% enlarges — which adds no new detail.
Applies to JPEG and WebP output only — PNG is lossless.
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How to use

  1. Drop images onto the box, or click it to browse — JPEG, PNG, WebP, GIF or BMP, up to 20 files and 30 MB each.
  2. Choose how to size them under Resize by: Percentage of original scales every image by one factor, while Width & height fits each to a target box.
  3. In percentage mode, set the slider anywhere from 1% to 200%. In dimensions mode, type a width and/or height and keep Lock aspect ratio ticked so each photo holds its own shape.
  4. Set the Output format — keep the source type, or convert to JPEG, PNG or WebP — then move the Quality slider, which only affects JPEG and WebP output.
  5. Images resize the moment they land; after you change any setting, press Resize with current settings to re-run the batch, then take each file or press Download all.

How it works

Every image is decoded off the main thread, with its EXIF orientation flag applied so a photo shot sideways still lands upright. The tool then computes the target size, hands the pixels to pica — a resampler running a Lanczos3 filter in a Web Worker — and writes the result back to a file through the canvas API.

What the target size comes to depends on the mode. Percentage multiplies both sides by the slider value. In Width & height mode with the ratio locked, the two numbers act as a bounding box: the image is scaled by the smaller of width ÷ original-width and height ÷ original-height, so it fits inside without stretching. Load a 4160 × 3120 phone photo (a 4:3 frame) and set the box to 1080 × 1080. The tool weighs 1080 ÷ 4160 = 0.2596 against 1080 ÷ 3120 = 0.3462, keeps the smaller, and scales everything by 0.2596 — the output is 1080 × 810, saved as beach-1080x810.jpg. The box was square, but the picture kept its 4:3 shape. Because JPEG carries no alpha channel, choosing it composites the image onto a white background first, and the 0.85 quality value is passed straight to the encoder.

Use cases & limitations

Reach for this the moment an upload form rejects your photo for being too big, when a blog or CMS expects images at a fixed column width, or when a folder of screenshots needs trimming to one consistent size before you file a bug report. Enlarging is possible too, though interpolation can’t reinvent detail the sensor never recorded, so blown-up images read soft.

Two limits are worth knowing. Everything is written back through a canvas, so an animated GIF collapses to its first frame — that one frame is saved as a PNG, not a moving image. And any lossy round trip recompresses: resizing a JPEG at 0.85 quality re-encodes it, so putting the same file through repeatedly will slowly soften its edges. When you want a smaller file at the same resolution, the image compressor trades quality for bytes without changing dimensions; to swap only the file type, the image converter is the direct path; and for square app icons at set sizes, the favicon generator handles the crop-and-scale in one pass.

Privacy note

Nothing you drop here is uploaded. Decoding, resizing and re-encoding all happen inside the tab — pica’s filter runs in a Web Worker on your device, and the page never issues a request that carries pixel data, so a batch finishes just as readily with the network switched off after the page has loaded. The file you download is a fresh copy; where it goes next is entirely your call.

Frequently asked questions

How do I resize an image without distorting it?

Leave Lock aspect ratio ticked. The width and height you enter then act as a box: each image is scaled to fit inside it and keeps its own shape, so nothing is stretched. Type one dimension and the other fills in from the loaded image's ratio — a 4032 × 3024 photo fitted to a 1200 px width becomes 1200 × 900. Untick the lock only when you deliberately want to force an exact width and height, which can squash the picture.

Does resizing an image make the file smaller?

Usually, because fewer pixels means fewer bytes to store. Halving both sides removes about three-quarters of the pixels — a 4000 × 3000 image at 50% becomes 2000 × 1500, a quarter of the area — and JPEG or WebP output shrinks roughly in step. If you want a smaller file at the same dimensions, the image compressor is the better fit: it trades quality for size without changing resolution.

Can I enlarge a small image?

Yes — set a percentage above 100, or a target larger than the source — but know what you get. Upscaling invents pixels by interpolating between the ones already there; it cannot recover detail that was never captured, so a 320 × 240 thumbnail blown up to 1280 × 960 looks soft. The Lanczos filter used here keeps edges cleaner than a plain browser stretch, but no resampler adds real detail that isn't in the original.

What resampling method does the resizer use?

Every image is resized with pica, which runs a Lanczos3 filter in a Web Worker. Against the bilinear scaling a browser does when you just set an <img> width, Lanczos holds fine edges and text with far less blur and fewer stair-step artefacts — which is why a downsized screenshot stays legible here. Large images are handled in tiles so the tab keeps responding while they process.

Are my photos uploaded anywhere?

No. Each file is decoded, resized and re-encoded entirely inside your browser tab — the resizing runs in a Web Worker on your own device, and the page makes no network request carrying image data. Open your browser's network tab while you drop a file to confirm it, and note the tool keeps working with the connection switched off once the page has loaded.

Does resizing keep transparency and photo orientation?

PNG and WebP output preserve the alpha channel, so transparent backgrounds survive. JPEG has no transparency, so converting to JPEG fills any transparent areas with white rather than the black a raw canvas would give. Orientation is read from the EXIF flag before resizing, so a portrait phone shot stays upright. The round trip through a canvas drops all other EXIF metadata, including GPS — a side effect, not a promise; use the EXIF remover when scrubbing metadata is the actual goal.