Resize an image to A4 print size (300 DPI)
The 3508 × 2480 box is preset — the A4 sheet converted to pixels at 300 dots per inch, the number behind every print-shop, office and school requirement — so this page maps your file onto that box in your browser and hands back a JPG ready to print at full sheet size.
Your images
Settings
Set both for an exact pixel size; set one and the other scales to keep the ratio.
Generated images
- Nothing uploaded
- Free, no sign-up
- Strips EXIF
- Batch files
A print requirement is always hiding a number. The photo lab says 300 DPI, the school says A4, the proof-of-concept says 'full sheet, no margins you can't control' — and the number nobody writes down is which edge is which, in pixels. A4's long edge is 297 mm, which at 300 dots per inch is 3508 pixels; the short edge is 210 mm, which is 2480. A file that sits at that resolution prints edge to edge at full A4 with nothing blurry; a file at half that resolution prints fine on a screen and soft on paper, and the lab's rejection notice rarely explains that it was an inches-to-pixels arithmetic problem.
This page does that arithmetic for you. The box is preset at 3508 wide and 2480 tall — A4's long edge over its short edge, in pixels — JPG is preselected because print pipelines list it first, and the mapping is literal: whatever you add comes out exactly 3508 × 2480. A 6000 × 4000 camera frame downscales onto the sheet with high-quality resampling and keeps its composition; a square or portrait source fills the box by stretching, which is the one reason to crop to the sheet's ratio first — and the crop button on the card is there for exactly that.
There is a second everyday role here: slimming a large photo down to fit the sheet. A 48 MP scanner output or a phone burst shot is heavy and oversized by a lot, and the same exact mapping does both jobs — the output is always the sheet size, and the output always weighs a few hundred kilobytes instead of the source's several megabytes. The original on disk is untouched, because all the resampling ran in your browser.
How it works
One decision matters — crop or fill — plus the quality slider if the destination is a size-capped upload.
Add the file
Choose it, drag it on, or paste it with Ctrl+V. A camera frame close to the sheet's own ratio is the cleanest input — it lands on the box with almost no stretch and the composition intact. Square and portrait sources work too, but read the fill behavior below before you generate, because a tall 3:4 frame in the wide sheet box stretches sideways and the face in it starts to read as an oval.
Crop the non-matching frames
The 3508 × 2480 box fills both dimensions, so a portrait or square source arrives stretched — a face in it now reads wider than it stands. Press the crop button on the card, drag the frame over the region that should carry the sheet, and generate from that region. Skip the crop only when the stretch will be invisible: a flat poster, a chart, a texture. If the subject sits center-frame, most of the sheet will still read correctly.
Generate, check the edges, download
Press Generate images. The card shows 3508 × 2480 and the new weight — for photographic content at the default quality of 82, usually between 800 KB and 2.5 MB, which every upload form and e-mail line will accept. Send it to the lab as the sheet file, or print it yourself at 100 percent scale. The Compare slider lets you glance at the result before you save.
Where the 3508 × 2480 number comes from
The pixels behind the preset come from pure mm-to-inch arithmetic. A4 is 210 mm by 297 mm — 8.27 inches by 11.69 inches. At 300 dots per inch, the 297 mm edge is 3508 pixels and the 210 mm edge is 2480. This page presets the wide direction as 3508 and the tall direction as 2480, so the output box is landscape A4 at print resolution; a requirement written 'A4 landscape, 300 DPI' is exactly this number, and 'A4 portrait, 300 DPI' is the same pair with the axes swapped (2480 wide, 3508 tall). At a lower standard like 150 DPI, or a 200 DPI one, the millimetres scale proportionally — 210 mm at those densities is between 1240 and 1654 px, 297 mm between 1754 and 2339 — which is why the same sheet can 'be' three different pixel sizes depending on the resolution the form quotes.
| How the sheet is quoted | Pixel size (w × h) |
|---|---|
| This page's preset — 297 mm side wide, 300 DPI | 3508 × 2480 px |
| The other axis order (210 mm wide), 300 DPI | 2480 × 3508 px |
| Same sheet at 150 DPI | 1754 × 1240 px |
| Same sheet at 200 DPI | 2339 × 1654 px |
Why 300 DPI is the sheet number that matters
A DPI figure on a print requirement is a density promise: how many ink dots the printer is allowed to place per inch. 300 is the floor where a photo on paper stops showing the pixel grid at arm's length, and it is the number labs, proof services and most school submissions quote. A file sized to 300 DPI of A4 — 3508 × 2480 — contains exactly the information a 300 DPI printer can place, no more, no less: print it at 600 DPI and it simply resizes, print it at 150 DPI and it has room to spare.
The practical consequence for this page: the preset is A4 at that density, so the output is print-honest regardless of what software re-interprets the DPI tag later. You do not need to know what your printer's 'photo size' dropdown thinks a sheet is — the pixel count is the sheet, at the density that matters for paper.
Downscaling a large photo to fit the sheet
The same preset is the cleanest way to shrink an oversized file without touching a slider. A 48 MP scanner frame (8192 × 5464), a 24 MP wedding burst, a 4K wallpaper: the exact mapping scales each one onto 3508 × 2480 with the browser's resampler, the output weighs a fraction of the source, and the composition survives because the sheet's ratio (about 1.41, between the 4:3 and 3:2 of most cameras) is close to the ratio of typical photos. The downsampling also quietly solves the weight problem: a file that was 30 MB becomes a few hundred kilobytes at quality 82, because three of its four pixels no longer exist — and no visible loss at printing distance, where the eye resolves 300 dots, not 3000.
What the page does not decide for you
Two design calls stay yours. The tool will not tell you which region of a portrait photo should fill the sheet — the crop frame does that, and it is the difference between a file the lab accepts and one they bounce. And it will not add a white margin, a background or a second image to fill a non-matching source: the box stretches rather than pads, because a padded sheet is a layout decision only you can make. If the sheet needs a white border, a caption or a second photo, that is a different document — a word processor or the studio's layout tool builds it, and this page gives it the correctly sized artwork to place.
Frequently asked questions
Why 3508 × 2480 and not some other A4 number?
Because it is A4's millimetre size — 210 × 297 — converted at 300 DPI: 8.27 inches × 300 dots and 11.69 inches × 300 dots gives the 2480 and the 3508. The same sheet at 150 DPI is half that pair (1240 × 1754), and at 200 DPI it sits in between (1654 × 2339). The 300 DPI pair is the one that prints sharp on paper, which is why the preset uses it; if your form quoted 150 DPI instead, halve the numbers and you have the same sheet.
My photo is tall (portrait 3:4) and the sheet is wide. What happens when I generate?
The box fills both dimensions, so the portrait frame stretches to be wider — nearly 90 percent wider for a 3:4 source, and a face in it starts to read as an oval. A chart or a poster tolerates it; a person does not. Press the crop button on the card, drag the frame over the part that should carry the sheet, and generate from that region; the 3508 × 2480 result then reads exactly as framed.
I need A4 portrait (taller than wide) — my certificate sits vertical. Can I do that here?
The preset is the wide sheet. For the one that stands up, the pair is the same sheet with the axes swapped — 2480 wide × 3508 tall — and any of the site's exact-size flows handles it the same way. If the requirement you are meeting says 'A4 portrait at 300 DPI', the number to enter is 2480 × 3508: the same 210 mm and 297 mm, just standing up.
The form says '3000 × 3000 minimum'. Is 3508 × 2480 acceptable?
It depends on the clause. If it is a minimum-resolution gate, 2480 on the short side may fall just under a 3000 floor — in that case the page's job is done and you need a square master instead. If it is 'sized for A4 at 300 DPI', then 3508 × 2480 is exactly the ask. Read the wording: 'A4 at 300 DPI' and '3000 pixels minimum' are two different requirements wearing similar clothes.
Will the photo be blurry if I print it at the photo lab?
No, provided the sheet is what you intend: at 3508 × 2480 the file carries exactly 300 DPI of A4, which is the lab's working resolution for full-sheet photo prints. Blurriness on a sheet this size almost always means the source was smaller than the box — in which case nothing a tool does after the fact will invent the missing detail, and a tighter crop from a higher-resolution master is the honest fix.
Do I leave my machine's local files, or the file itself, to build this?
Nothing leaves your device. The resampling to 3508 × 2480 and the JPEG encode run in your browser, the original in your camera roll or hard drive is byte-identical afterwards, and the only network event is the site's own assets. For a document with a personal face on the sheet, that matters.