Fit images to target aspect ratios by adding letterbox bars or cropping.
Cameras produce 4:3, 3:2, and 1:1 photos, but the frames you place them in - social posts, video timelines, print sizes - usually want 16:9, 1:1, or 9:16. This tool compares the photo's width and height with the ratio you enter and matches the frame exactly one of two ways: letterboxing adds solid-color bars on the short side and keeps every pixel; cropping removes the overflow and fills the frame completely. Content is never stretched or resampled. What surprises people: the bars are permanent pixels in the output file, visible in prints and thumbnails, and cropping permanently deletes what it cuts away.
A concrete input and expected output from the current implementation.
Input
1920x1080 photo, target ratio 1:1, run in both modes
Expected output
Letterbox: 1920x1920 image, 420px bars across top and bottom. Crop: 1080x1080 image, 420px removed from each side.
A square must be built from the 1080px height, since the photo is wider than 1:1. Letterboxing pads the height from 1080 to 1920, adding 420px of bars above and below; cropping cuts the width from 1920 to 1080, removing 420px from each side.
The tool divides the photo's width by its height and compares that ratio with the one you entered. If the photo is wider than the target, the fit is built on the height: letterboxing pads above and below, cropping trims left and right. If the photo is narrower, the roles swap: bars go on the sides, or the top and bottom get cut. When the ratios already match, nothing changes.
Letterboxing appends solid-color rows or columns so the image's pixel dimensions match the target ratio while every original pixel stays untouched. Cropping discards the overflow rows or columns, shrinking the pixel dimensions. Neither mode scales the photo, so fitting is not resizing: a 4000x3000 photo fitted to 16:9 becomes about 5333x3000 with bars, or 4000x2250 cropped - never 1920x1080. Fractional results like 5333.33px round to whole pixels.
No. The bars are baked into the file as ordinary pixels, so every destination shows them - the post, the thumbnail, the print. Platforms that add their own frame stack it on top of yours, which can double the bars. If you want the frame filled edge to edge, crop instead and accept the lost edges.
Neither mode resamples, so the pixels that remain are the original pixels at full quality: no blur, no softening. Letterboxing adds pixels, cropping removes them. The real cost is compositional - bars change the frame's shape, cropping changes the content. To hit a specific resolution afterward, resize separately.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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