Free Image Resizer Online

How the image resizer works

The browser decodes each selected image, calculates the requested output dimensions, draws the pixels onto a new canvas with high-quality smoothing, and encodes a metadata-free JPEG, PNG, or WebP file.

Resize a 2400 × 1600 image to 1200 pixels wide

With the aspect ratio preserved, the scale factor is 0.5 and the output becomes 1200 × 800 pixels. Prevent-upscale mode leaves images smaller than the requested width at their original dimensions.

Using the processed image

Keep the exported dimensions, format, transparency, and compression level appropriate for where the image will be used.

canvas.width = outputWidth;
canvas.height = outputHeight;
context.drawImage(bitmap, 0, 0, outputWidth, outputHeight);

const outputHeight = Math.round(
  sourceHeight * outputWidth / sourceWidth
);

Using the result accurately

Resize to the largest dimensions the final layout actually needs. Keep the aspect ratio locked for photographs and interface assets unless intentional distortion is required, and inspect text or fine detail after a large reduction.

References: MDN CanvasRenderingContext2D drawImage().