Resize Images with Social-Media Presets and Lanczos Downscale
14 social-media presets baked in (Instagram square, X header, OG 1200×630, LinkedIn banner). Lanczos downscale; tested 8 MP photo → 1080 px in 0.4 s. All in-browser, no upload.
Resize Image NowWhat this tool does: resize by pixel dimensions, percentage, or social-media preset
Choose from three resize modes. Pixel dimensions let you enter exact width and height with aspect ratio lock. Percentage scales the image up or down by a factor. Social-media presets apply platform-recommended dimensions instantly — pick Instagram Square, X header, LinkedIn banner, and 11 more.
Pixel dimensions
Enter exact width and height. Aspect ratio lock keeps your image proportional. Supports any positive pixel value up to 10000×10000.
Percentage scaling
Scale by percentage — 50% halves the image, 200% doubles it. Useful for bulk resizing where all images need the same relative reduction.
Social-media presets
14 platform-specific presets with correct aspect ratios. Select a preset and upload — the tool handles the rest with Lanczos downscale for maximum sharpness.
Presets included: Instagram square, X header, LinkedIn banner, OG image (1200×630)
All 14 presets cover the most common social-media and content dimensions: Instagram (square, portrait, story), Facebook (cover, post), X / Twitter (header, post), LinkedIn (cover, post), YouTube thumbnail, TikTok, Pinterest pin, Discord banner, and email header.
Each preset maps to exact pixel dimensions recommended by the platform. For example, the X (Twitter) Header preset outputs 1500×500 px — the 3:1 ratio that keeps the header fully visible on desktop and mobile. The OG Image preset (1200×630 px) matches the standard Open Graph image size used by link previews across Facebook, X, LinkedIn, and Slack.
Select any preset from the picker in the tool above. The dimensions fill automatically. You can switch between presets or clear the selection to enter custom dimensions instead.
How resampling works: Lanczos for downscale, bicubic for upscale
When downscaling (reducing image size), the tool uses the Lanczos resampling algorithm via the pica library. Lanczos is a windowed sinc filter that preserves sharp detail better than bilinear or bicubic interpolation — edges remain crisp and text stays readable. The resampling runs in a Web Worker via WebAssembly for performance, keeping the UI responsive.
When upscaling (enlarging an image), the tool uses the browser's built-in bicubic interpolation with high-quality image smoothing. Bicubic is the standard choice for upscaling because it produces smoother results than Lanczos when generating new pixels.
This hybrid approach — Lanczos for downscale, bicubic for upscale — matches industry practice for photo editing software. The result is noticeably sharper downscaled output compared to plain Canvas API interpolation, especially on high-detail images like product photos, screenshots, and text-heavy graphics.
Limits: 100 MP source resolution, batch up to 30 files
Each image must be under 50 MB. The tool supports batch processing of up to 30 files at once — upload multiple images, pick a preset or dimensions, and resize them all in one click. Source resolution is capped at approximately 100 megapixels (roughly 10000×10000 px), which covers virtually all consumer camera photos, including high-resolution smartphone and DSLR images.
All processing happens in your browser using WebAssembly and Web Workers. Images are never uploaded to any server. Resized results can be downloaded individually or as a single ZIP archive.
FAQ
Will resizing distort the image if my target dimensions are a different aspect ratio?
The aspect ratio lock keeps width and height proportional — no distortion when enabled. If you unlock it, the image stretches to fit non-proportional dimensions. For most use cases, keep the lock enabled, or use a preset which is already proportionally correct.
What's the best preset for a Twitter / X header?
Use the 'X (Twitter) Header' preset which outputs 1500×500 px — the current recommended header dimensions as of 2026. The aspect ratio is 3:1, which keeps the full header visible without cropping on desktop and mobile views.
Can I resize while keeping the file under a target byte size?
Not directly. The tool resizes by pixel dimensions and quality, not by file size. To hit a specific byte target, resize to smaller dimensions first, then use the quality slider to reduce the output file size further. For aggressive size reduction, run the result through the Image Compress tool.
Does resizing reduce quality more than compression does?
Resizing down discards pixel data but does not introduce compression artifacts — it simply has fewer pixels. Compression at the same resolution introduces artifacts by discarding image data within each pixel. For the smallest file size, resize first (with Lanczos downscale for best sharpness), then compress.