Image Resize

Upscale images 2x, 3x, or 4x with Lanczos interpolation

How It Works

The resize tool enlarges images at 2x, 3x, or 4x using Lanczos interpolation, one of the highest quality resampling algorithms available. The simple bilinear scaling browsers apply by default averages neighboring pixels, which is why enlarged images usually come out blurry. Lanczos computes each new pixel from a weighted window of surrounding pixels, so edges and fine detail stay sharp.

Under the hood the tool uses the open-source Pica library at its highest quality setting, Lanczos3. Everything runs in your browser: the image you pick is read locally and nothing is uploaded to any server.

Why Lanczos? Lanczos resampling uses a windowed sinc function to weigh the surrounding pixels. It produces sharper results than bilinear or bicubic methods, especially when enlarging, and it is the same algorithm professional tools like Photoshop and GIMP offer for resizing.

Key Features

Three scale factors

Choose 2x, 3x, or 4x. The tool multiplies both dimensions and keeps the aspect ratio.

Sharp results

Lanczos3 preserves edges and detail far better than default browser scaling.

Side-by-side comparison

The upscaled image appears next to the original, with the dimensions of each shown.

Private

All processing happens locally. Your images never leave your browser.

Scale Options

Factor	Result
2x	Doubles width and height (4x the pixels)
3x	Triples width and height (9x the pixels)
4x	Quadruples width and height (16x the pixels)

The output keeps the original aspect ratio and downloads as a PNG.

Best Use Cases

Enlarge images for higher resolution printing.
Scale up small photos or thumbnails to usable sizes.
Prepare small source images for high-density screens.
Upscale older, low-resolution photos before sharing them.

Supported Formats

Input can be any image your browser can open:

JPEG / JPG
PNG
WebP
GIF
BMP

The result downloads as a PNG, which keeps the upscaled image lossless. If you need a smaller file afterwards, run it through the converter.

Tips for Best Results

Start with the highest resolution source you have. Lanczos keeps existing detail sharp, but no interpolation can add detail that was never there.
For enlargements where you want new detail generated, try the AI Resize tool instead.
Very large sources multiplied by 4x can exceed browser memory limits, so a 2x pass is safer for big images.

Resize vs AI Resize

Not sure which tool to use? Here is the difference:

Standard Resize	AI Resize
Lanczos interpolation, keeps existing pixels accurate	Neural network predicts new detail
Fast, no model download	Downloads an AI model on first use
Works on any device	Slower, works best on capable devices
2x, 3x, or 4x	4x only

Try Resize Tool →