Resize image
Scale images to exact pixel dimensions or by percentage. Lock the aspect ratio optionally. Output as JPG, PNG or WebP. No upload.
About this tool
In shortResize an image to new pixel dimensions — lock-aspect, Lanczos resampling, locally in your browser.
Scaling means producing a new pixel grid for an image — usually smaller (the common case: reducing an original photo to web size), occasionally larger (rarely worth it, since upscaling doesn't add real detail). The resize uses a mathematical resampling algorithm: each target pixel is computed from a weighted blend of multiple source pixels.
This tool resizes images locally in your browser. The default resampler is Lanczos — a high-quality method also used by Adobe Photoshop for premium resizes. Compared to simpler methods like Nearest-Neighbor (pixelated) or Bilinear (mushy), Lanczos delivers the sharpest results at the same file efficiency.
Keep lock-aspect on.The most important default. Forcing a 4:3 photo to 1920×1080 without lock-aspect stretches it horizontally — faces widen, circles become ellipses. Keep lock-aspect on and enter only one dimension (width or height); the other adjusts automatically. For a different framing, crop first via the cropper.
Sensible target dimensions.Rules of thumb: web (standard container) — max 1200 px wide. Hero images with Retina — 2400 px. Thumbnails — 400 px. Email attachments — 1600 px. WhatsApp — 1280 px. Application photos — 800 px tall. Print (A4 at 300 dpi) — 2480 × 3508 px. Detailed table in resize an image online — guide.
What you shouldn't do.Upscale beyond the original resolution. The tool will produce a larger file, but the extra pixels are interpolated, not pulled from reality. The result looks softer and less sharp than the original. If you need a larger source, go back to it (camera RAW, higher CMS resolution) — AI upscalers like Topaz Gigapixel are an option for extreme cases, but no miracle.
Two-axis input.You can enter width OR height. To force both (e.g. a specific aspect), turn off lock-aspect — but the image will stretch if the target ratio differs from the source.
Output format.The tool outputs in the same format you uploaded (unless you actively pick another). To resize AND optimize in one step, use the Multi-Format Compare instead.
Privacy.Local in your browser. No upload. Related: resize an image online — guide, scaling images — guide.