Resizing sounds simple until you have to decide what happens when your target dimensions do not match the original proportions. This tool gives you three explicit answers to that question rather than guessing. It accepts PNG, JPG, WebP and HEIC, and shows a live preview of the actual output shape before you commit.
Fit treats your numbers as maximum bounds and keeps the entire image visible, so the result may be smaller than requested in one dimension. Crop gives you exactly the dimensions you asked for by cutting off the overflow, centred. Stretch also gives exact dimensions but squashes the image to reach them.
No. If your requested size has the same proportions as the original, there is nothing to crop or stretch, so all three produce the same result. Change one number to a different shape and the difference becomes obvious immediately.
Not in Fit mode, which caps scaling at 100 percent to avoid producing a blurry upscale. Crop and Stretch will honour dimensions larger than the source, but enlarging cannot add detail that was never captured.
The same format as your input, so a PNG stays a PNG. The exception is HEIC, which is converted to JPG because browsers cannot write HEIC.