Resize a Photo for 4x6 Printing
Four by six inches at the photographic standard of 300 dots per inch comes to 1800 x 1200 pixels, in the 3:2 shape inherited from 35mm film and still native to most dedicated cameras. Phone cameras mostly shoot 4:3, and that mismatch — not megapixels — is what ambushes people at the print kiosk. Below: how to make the crop decision yourself, what resolution the paper actually needs, and what to do when your pixels fall short of the number.
Pixels for common print sizes
| At 300 DPI | At 240 DPI | |
|---|---|---|
| 4 x 6 in | 1800 x 1200 px | 1440 x 960 px |
| 5 x 7 in | 2100 x 1500 px | 1680 x 1200 px |
| 8 x 10 in | 3000 x 2400 px | 2400 x 1920 px |
Your 4:3 phone photo must lose something
A 4:3 image does not fit 3:2 paper. Order the print anyway and the lab makes the choice for you: "fill" trims about a ninth of the image height off the top and bottom, where hats and heads tend to live, while "fit" keeps every pixel and pads the sides with white bands.
Making the call here costs a minute and shows you the outcome. Resize with Fill & Crop to 1800 x 1200 and the download is precisely what the paper will carry — inspect it, and if the trim took something you care about, go to the image cropper, frame the 3:2 window yourself, and resize that instead. If you would rather keep everything and accept borders, order the print as "fit"; no resize can conjure a 3:2 picture out of a 4:3 one without either trimming or bands.
How many dots the paper really needs
The 300 DPI convention marks the point where a photographic print stops gaining at normal viewing distance, and it is the number the 1800 x 1200 target assumes. It is a target, though, not a cliff: prints made from 240 DPI — 1440 x 960 for this paper — are typically indistinguishable in an album held in the hand, which is why the table above carries both columns.
The floor is lower still. Down to around 150 DPI a 4 x 6 remains acceptable on a fridge door; beneath that, softness becomes the first thing anyone notices. Translated into files: a 1500-pixel-wide photo prints this size at 250 DPI and will look simply fine, no enlargement required. Count your pixels before assuming you need more of them.
Short on pixels? Enlarging here won't print sharper
Typing 1800 into the width box when the photo holds 900 doubles the pixel count without adding a single detail — interpolation stretches what exists, and stretched detail prints soft at reading distance. The file satisfies the lab's checklist and disappoints on paper. The panel's anti-enlargement checkbox exists to refuse exactly this request, and it is worth leaving on.
Three routes that actually work. Print the size your pixels support: 900 wide is a solid 3-inch side at 300 DPI. Let the AI upscaler reconstruct detail first — it infers texture with a trained model rather than averaging neighbours — then come back and land the result on exactly 1800 x 1200. Or simply accept the 240 DPI column and print anyway; for a snapshot in an album, that is often the right call, and it costs nothing.
Frequently Asked Questions
What pixel size is a 4 x 6 print?
1800 x 1200 at the 300 DPI standard; 1440 x 960 at 240 DPI still prints well. For portrait-orientation shots, swap the numbers and enter 1200 x 1800 so the box matches the photo.
The lab cropped my photo. How do I prevent that?
Make the trim yourself before ordering: Fill & Crop at 1800 x 1200 shows you exactly what will reach the paper. If nothing may be lost, ask the lab for a "fit" print and accept the white bands.
My file says 72 DPI. Is it unprintable?
The header value means nothing — count pixels instead. A so-called 72 DPI file that measures 1800 x 1200 prints a perfect 4 x 6, because the density on paper comes from pixels divided by inches, not from the label.
Can I prepare a stack of prints in one run?
Ten photos per round, all receiving the same target box. Landscapes and portraits need opposite boxes — 1800 x 1200 versus 1200 x 1800 — so sort them into two runs before you start.
Should I hand the lab a JPEG or a PNG?
A high-quality JPEG. Print pipelines are built around it, and a PNG of a photograph is typically several times heavier with nothing visible gained on paper.