Rotate Image

Phones, scanners and webcams often save pictures sideways, and a slightly tilted horizon spoils a good photo. This tool turns images by a quarter turn, a half turn or any angle you type, either keeping the whole picture on a larger canvas or cropping it so no empty corners show. It works on a whole batch at once, entirely in your browser.

How to use this tool

1. Choose one or more images.
2. Pick 90° clockwise, 90° counter-clockwise or 180°, or “Custom angle” and type the degrees (positive turns clockwise).
3. For custom angles choose how to handle the corners: expand the canvas, crop to fill, or keep the original size.
4. Set the corner fill (transparent or a colour) and the format, then download the rotated images.

Formula

Expanded size = (W·|cos θ| + H·|sin θ|) × (W·|sin θ| + H·|cos θ|)

Crop to fill keeps the original proportions and shrinks the frame by s = min(W ÷ (W·cos θ + H·sin θ), H ÷ (W·sin θ + H·cos θ)), the largest centred rectangle that fits entirely inside the rotated picture. Quarter turns use exact integer transforms, so every pixel lands in its new place without any blur.

Example

A 4000 × 3000 px photo turned 90° clockwise becomes 3000 × 4000 px. Straightening it by 2° with “expand” gives 4000·0.99939 + 3000·0.0349 ≈ 4102 × 3138 px with thin filled corners, while “crop to fill” gives 3824 × 2868 px (s = 3000 ÷ 3137.8 ≈ 0.956) with no corners at all.