Resize images online free — set custom pixel dimensions with aspect ratio lock. Export as PNG, JPG, WebP, BMP or GIF. Browser-based.
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Image Resizer lets you set width and height in pixels with an aspect ratio lock option. Output in PNG, JPG, WebP, BMP, or GIF format.
Yes, with the 'Lock Ratio' option, entering either width or height will automatically maintain the aspect ratio.
Turn the ratio lock off and type the width and height directly, and the output matches those pixels exactly. If the numbers do not match the original ratio the picture will stretch, so for fixed formats like avatars or thumbnails crop to the right ratio first and resize afterwards.
Yes. Pixels that were never captured have to be invented from neighbouring values, so edges soften and detail smears as you scale up. Scaling down discards information and stays clean, but beyond about 2× enlargement the loss becomes obvious — go back to the original high-resolution file whenever you can.
Instagram uses 1080×1080 for square posts, 1080×1350 for portrait and 1080×1920 for stories and reels. Profile pictures work best as squares of at least 400×400, YouTube thumbnails are 1280×720, and Open Graph share images should be 1200×630.