JPG のサイズ変更

Halving the width and height of a photo leaves a quarter of the pixels, and file size follows. Our 1200 × 800 test JPG of 224,092 bytes became 84,961 bytes at 800 × 533, quality 90. A 2400 × 1600 photo of 631,537 bytes resized into the 1080 × 1080 Instagram preset with Fit came out at 1080 × 720 and 133,858 bytes. Most upload forms and messaging apps scale large photos down anyway; doing it yourself means you choose the size and the quality instead of the website.

For a hard file size limit, such as 200 KB, resize first to the dimensions the form asks for, then use the compressor to reach the number.

Fit keeps the proportions and stays inside the box, which is why a 3:2 photo in a 1080 × 1080 box becomes 1080 × 720. Cover fills the box completely and trims the overflow from the centre, so the same photo becomes a full 1080 × 1080 square with its sides cut. Fill and Exact dimensions both force the exact numbers and stretch faces and buildings if the shapes differ.

When the subject is not in the middle, press Crop on the photo and move the frame yourself; it is locked to the target shape, and the area you pick fills the output exactly. Presets include Instagram post (1080 × 1080) and story (1080 × 1920), Facebook cover (820 × 312), LinkedIn post (1200 × 1200), YouTube thumbnail (1280 × 720), Pinterest pin (1000 × 1500) and X (Twitter) header (1500 × 500).

The output is encoded at quality 90 by default, high enough that the resize itself is the only visible change; lower the slider if you also want a smaller file. PNG, WebP, BMP and GIF images added here are converted to JPG, and any transparent areas turn white. The resized file carries no EXIF data, so the camera details and GPS location are gone. The photo is drawn upright first, so a portrait phone photo stays portrait.

Your photos are decoded, scaled and saved in the browser tab. Nothing goes to a server, and closing the tab discards everything. Each file may be up to 50 MB and each side up to 10,000 pixels; Download all saves the whole batch as a ZIP.