Documents, reports and covers printed in the US or Canada
Flyers and handouts for a North American audience
Certificates, in landscape
Anything going to a North American office printer
Resizing to US Letter
Letter is not A4, and the difference matters
US Letter is wider and shorter than A4: 8.5 × 11 inches against 8.27 × 11.69. A Letter design printed on A4 paper loses about 6 millimetres of width and gains 17 millimetres of height, which shifts every margin and can clip a full-bleed edge.
Software papers over this by scaling to fit, which is worse than it sounds. Scaling a Letter page onto A4 shrinks everything by about 3% and adds an uneven margin; the page still prints, and it no longer matches the design.
For a document with an international audience, either produce both sizes from one source or design the content inside the area common to both, and accept slightly larger margins on one of them.
Why 2550 × 3300
8.5 inches at 300 dots per inch is 2550 pixels, and 11 inches is 3300. The arithmetic is simpler than A4's because the physical size is already in inches, which is the unit DPI is defined against.
For full bleed, the North American convention is 0.125 inches on each side, making the working canvas 2625 × 3375 for a page that trims to 2550 × 3300. Keep anything you need to survive at least 0.5 inches inside the trim.
Between bleed and safe margin, roughly the outer 0.6 inches of the design is either discarded or at risk.
Portrait, landscape, and certificates
Letter is quoted portrait. Rotated to 3300 × 2550 it becomes the standard North American certificate size, which is landscape by convention — and the reason certificate templates come in Letter landscape and A4 landscape variants rather than one universal size.
If a certificate will be framed, note that Letter frames are stocked in North America and A4 frames largely are not, and the reverse is true everywhere else. Print to the size your recipient can frame.
Yes. Resizing JPG, PNG, and WebP images is completely free with no sign-up, no watermark, and no file limit. Resizing runs entirely in your browser, so there is nothing for us to charge for. Pro plans add the AI tools, but everyday resizing stays free forever.
Are my images uploaded to a server?
No. OpusImg resizes images on your own device using WebAssembly and your browser's own canvas. Your files never leave your computer or phone — there is no upload, no cloud processing, and nothing stored on our side. That makes it safe for confidential documents, client work, and personal photos.
How do I resize an image to exact pixel dimensions?
Choose the "By dimensions" mode and type the width and height you need in pixels. Leave the aspect-ratio lock on to keep the image's proportions — change one field and the other follows automatically. Turn the lock off when you need an exact, possibly non-proportional canvas, such as a specific banner size.
What is the lock aspect ratio toggle for?
When the lock is on, the width and height stay proportional: setting the width to 1000px updates the height to match the original shape, so the picture is never squashed or stretched. When the lock is off, you can set width and height independently, which is useful for fitting an exact canvas even if it distorts the image slightly.
Which resampling algorithm should I pick?
Use Lanczos for photographs — it produces the sharpest, most natural result and is the default. Bicubic is a fast, smooth alternative handled by your browser. Choose Nearest neighbour only for pixel art, sprites, or icons where you want hard edges and no blending between pixels when scaling up.
What does the DPI setting do?
DPI (dots per inch) is metadata that tells print software how large to print the image. It does not change the pixel dimensions or how the image looks on screen — 72 DPI is standard for the web, while print shops usually want 150 or 300 DPI. We embed the value you choose into the file (PNG and JPG) so a print workflow reads the right density.
Can I resize for Instagram, YouTube, or other platforms?
Yes. The "By preset" mode includes 18 ready-made sizes — Instagram square, portrait, and story; Facebook and LinkedIn covers; X/Twitter headers; YouTube thumbnails and channel art; Pinterest pins; plus HD, QHD, and 4K. Pick a preset and your image is resized to the exact canvas that platform expects.
Will resizing reduce image quality?
Making an image smaller (downscaling) keeps it looking crisp — Lanczos and bicubic both average pixels cleanly. Making it larger (upscaling) can only invent so much detail, so very large enlargements look soft; for big upscales the AI upscaler in Pro reconstructs detail far better. We encode the result at high quality so the resize itself adds no visible compression artifacts.
Can I resize many images at once?
Yes. Drop a whole folder and apply one target to the batch. In percentage mode every image is scaled by the same percentage, so each keeps its own aspect ratio; in dimensions or preset mode every image is fitted to the same canvas. Results are bundled into a single ZIP for download, all processed on-device.
What formats can I resize?
You can drop in JPG, PNG, WebP, AVIF, GIF, BMP, TIFF, and HEIC. Each file is decoded in your browser, resized, and re-saved — JPG and HEIC come out as JPG, PNG/BMP/TIFF as PNG, and WebP/AVIF/GIF as WebP, so the result always opens everywhere. To change format deliberately, use the converter tool linked below.