Processed locally in your browser — nothing is uploaded.
Image Resizer
Quick answer
Resize an image by exact pixels or by percentage, with the resampling handled by a Lanczos3 filter instead of a browser default that was built for speed, not sharpness.
What the image resizer does
Most in-browser resizing runs through the canvas drawImage call, a fast bilinear scale. It is fine for a thumbnail nobody will inspect closely, but it blurs fine detail and lets diagonal edges go ragged. Pixora instead runs the resize through jsquash/resize, a WebAssembly build of the same Lanczos3 kernel used in ImageMagick and Photoshop, so text and fabric patterns survive the scale.
You can drive the resize by target width and height in pixels, or by a percentage of the original — useful when you want "half size" but have not calculated the pixel value. The aspect-ratio lock keeps width and height moving together so a portrait photo does not turn into a stretched oval when you only meant to shrink it.
The preset row covers the sizes people search for most: Instagram square at 1080×1080, Instagram or TikTok story at 1080×1920, YouTube thumbnail at 1280×720, Facebook cover at 820×312, X post image at 1600×900, LinkedIn banner at 1584×396, plus flat 1080p and 4K for video work. Click one and the width and height fields fill in on their own.
How to use it
Add the image
Drop a file onto the canvas, click to browse, or paste it from the clipboard.
Pick pixels or percentage
Switch the input mode, then type a target width or height, or a scale percentage.
Lock the aspect ratio
Toggle the lock so the other dimension updates automatically and nothing distorts.
Use a preset if it fits
Tap a social or video preset button to fill in a common target size in one click.
Export
Download the resized file as PNG, JPEG, or WebP once the preview looks right.
Your images never leave your device
The resize runs entirely on the canvas and WebAssembly inside your tab. That matters when the file is not really yours to send elsewhere — a contractor resizing floor plans under an NDA, or a hospital admin shrinking a scanned form before it enters a records system with a small upload limit. The pixels never leave the machine.
- No file is ever uploaded to a server
- Works offline after the first visit
- No account, no watermark, no limits
Format and quality tips
Downscaling and upscaling are different problems
Shrinking an image means many source pixels collapse into one output pixel, and a filter that only samples a couple of neighbours will alias — shimmering moire on brick walls, striped shirts, and small text. Lanczos3 averages a wider neighbourhood, which is why it holds up on detailed photos. Enlarging is the opposite problem: stretching a 400 px photo to 2000 px produces a soft 2000 px image, not a sharper one. No filter invents detail that was never captured.
Nearest-neighbour has exactly one good use
A nearest-neighbour or "pixelated" mode belongs to pixel art and icon sprites, where each source pixel is a deliberate block of colour. Applied to a photograph it produces jagged, blocky edges, because it repeats the closest sample instead of blending.
Frequently asked questions
Will resizing a photo make it sharper?
No. Resizing only changes pixel count; it cannot add detail the camera never captured. A good filter avoids making the image worse, not better than the source.
What resampling method does this tool use?
Lanczos3, run through a WebAssembly module rather than the browser canvas default. It preserves edge contrast and fine texture noticeably better than a plain bilinear scale.
Should I resize by pixels or by percentage?
Use pixels when a platform or form specifies an exact size, like a 1280×720 thumbnail. Use percentage when you just want smaller and have no target number in mind.
Why does my resized image look soft compared to the original?
Any downscale discards information, and any upscale stretches what is already there. Some softness is unavoidable; Lanczos minimises it but cannot eliminate it.
Does locking the aspect ratio crop anything?
No. The lock only keeps width and height proportional as you type; it never removes pixels. Use the crop tool if you need to cut part of the frame away.
Can I resize to an exact file size instead of pixel dimensions?
Not here — this tool only controls dimensions. Pair it with the compressor on Pixora if you also need to hit a byte limit.
Further reading
- Social Media Image Sizes: The Cheat SheetThe sizes you actually need, in one table, and the reason a correctly-sized image beats a giant original: every platform re-encodes what you upload, so the pixels you send are never the pixels people see.6 min read
- Passport Photo Size GuideThe official sizes for US, UK, EU, India, China, Canada, Australia and Japan photos, converted to pixels at 300 DPI with the arithmetic shown — and a clear line on what a resizing tool can and cannot verify.6 min read
- How to Crop Images Without Losing QualityCropping does not blur anything — it just removes pixels at the edges. What actually costs you quality is re-encoding a JPEG and enlarging the crop afterwards. Here is how to avoid both.6 min read