The cheapest print in the world and the one ratio that matches a camera sensor exactly. Whether your photo needs cropping depends entirely on what took it.
Standard photo prints from a kiosk, drugstore or online lab
Postcards and small mailers
Photo album and wallet-sized sleeves
Contact prints and proofs
Resizing to 4 × 6 inch photo print
3:2 is a camera ratio, not a phone ratio
A 4 × 6 print is 3:2, and that is not a coincidence: 35 mm film was 36 × 24 mm, also 3:2, and digital SLR and mirrorless sensors inherited it. A photograph from a dedicated camera fits a 4 × 6 print with nothing cropped at all, which is why 4 × 6 became the default size.
Phones are mostly 4:3. A 4:3 photograph cropped to 3:2 loses about 11% of its height — a band off the top, the bottom, or both. That is usually harmless and occasionally fatal, and the difference is whether anything you care about was near an edge.
The practical habit is to leave a little air above heads and below feet when you shoot on a phone knowing the result will be printed. You are not composing for the frame you see; you are composing for a slightly shorter one.
Why 1800 × 1200
Six inches at 300 dots per inch is 1800 pixels, and four inches is 1200. Three hundred DPI is roughly where the eye stops resolving individual dots at reading distance, which is the standard for anything held in the hand.
A photograph with fewer pixels can still be printed at 4 × 6 — it will simply be printed at a lower DPI and look softer. A 1200 × 800 image prints at 200 DPI, which most people would accept; a 600 × 400 image prints at 100 DPI, which most would not.
Going the other way is free. A 12-megapixel phone photograph has roughly nine times the pixels a 4 × 6 needs, so downscaling to 1800 × 1200 discards data you were never going to see and produces a smaller, cleaner file.
Orientation and the lab
4 × 6 is normally quoted landscape and printed either way — labs rotate the paper rather than the image. Supply the image in the orientation you want it printed and the aspect ratio takes care of the rest.
Most labs also expect a little bleed, or trim a millimetre or two from each edge. Keep faces and anything you would notice losing away from the very edge of the 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.