A4 size in pixels depends on a number the paper does not carry: the DPI. ISO 216 fixes the sheet at 210 × 297 mm, or 8.27 × 11.69 inches, and each DPI turns that into a different grid: at 72 DPI, 595 × 842; at 96, 794 × 1123; at 150, 1240 × 1754; at 200, 1654 × 2339; at 300, 2480 × 3508; at 600, 4961 × 7016, which most charts round down to 4960. Scanners, print shops and PDF makers assume the 300 DPI pair, and this page produces it.
Drop a photo or a scan and it comes back at 2480 × 3508 without a click. The boxes already hold 210 and 297 in mm with 300 as the DPI, and “Crop to fill” is on, so a picture of another shape loses an equal strip from two opposite edges instead of being squashed. The JPG or PNG carries 300 DPI inside it, so a viewer or a print counter reports A4 rather than guessing from 72 or 96.
Before and after
2400 × 1597 px559 KBJPG
2480 × 3508 px975 KBJPG
The dashed frame on the left marks the part that fits the new shape. It was scaled to exactly 2480 × 3508 px, and the left and right edges outside the frame were trimmed.
The file went from 559 KB to 975 KB.
The numbers are from a real run of the tool above. The pictures here are smaller previews of the actual files.
How to use it
- Add the image to resize to A4 size: a phone photo of a page, a scanned certificate, a poster design.
- Read the result card: 2480 × 3508 means the sheet is filled at 300 DPI; the file weight sits beside it.
- For another figure, change the DPI box, or type 297 and 210 for landscape, then press Resize. Tapping px shows the same size in pixels.
- Download the file, or take it to the image-to-pdf tool when the office wants a PDF page rather than a picture.
Where the pixel figures come from
A pixel count for paper is inches multiplied by dots per inch. The sheet is 8.268 inches wide and 11.693 tall, so at 300 DPI the width needs 2480.3 dots and the height 3507.9, rounded to the A4 pixel size at 300 DPI of 2480 × 3508. Change the DPI and only the multiplier moves: 150 halves both figures, 600 doubles them to 4961 × 7016, the width rounding up because 4960.6 sits past the halfway mark. The shape stays put: height is always 1.414 times width, the square root of two.
The 72 and 96 figures are screen conventions rather than print sizes. PDF counts 72 points to the inch, so a reader describes an A4 page as 595 × 842 points; CSS counts 96 pixels to the inch, which gives 794 × 1123. Neither prints well: 794 pixels at 300 DPI cover only 67 mm of the sheet.
What a phone scan keeps and loses
The 12-megapixel camera in most phones gives a 3000 × 4000 frame, a 3:4 shape; A4 at 1:1.414 is a little narrower. “Crop to fill” keeps the full 4000-pixel height, takes about 86 pixels off each long side and scales the remaining 2828 × 4000 down to 2480 × 3508, so little is lost and nothing is enlarged. A sideways shot aimed at a portrait sheet fares far worse, keeping only 2121 of its 4000 pixels of width, so turn the sheet to landscape for it.
The tool resizes the whole frame and does not look for the edges of the paper, so a certificate photographed on a desk becomes an A4 picture of the desk. Crop to the paper first. Shadows, keystone and the camera’s softness all stay: the stored DPI only says how densely the pixels are to be printed and adds no detail a flatbed scanner would have recorded. A colour page photo typically weighs 1 MB to 3 MB at this size; a tighter cap wants a lower DPI or the compressor.
A4 against Letter, and the PDF case
North American offices print on Letter, 8.5 × 11 inches or 216 × 279 mm; at 300 DPI that sheet needs 2550 × 3300 pixels. It is about 6 mm wider and 18 mm shorter than A4, and its 1:1.29 shape sits closer to a 4:3 phone photo. For the United States or Canada, enter 216 and 279 here, or switch the unit to inch and type 8.5 × 11.
Some portals want the sheet as a PDF, not a picture. The IBPS notification for CRP PO/MT-XV (2025) says of the 10th standard certificate: document must be in PDF format; page size of the document to be A4; size of the file should not be exceeding 500 KB. The CSA-XV, SPL-XV and RRBs XV notices carry the same lines. Resize here at 200 DPI (1654 × 2339), then open the image-to-pdf tool, choose A4 and type 500 as the cap.
Frequently asked questions
- What is A4 size in pixels at 300 DPI?
- Portrait 2480 × 3508, landscape 3508 × 2480: 8.27 × 11.69 inches multiplied by 300 and rounded, what a flatbed scanner produces at 300 and what this page makes unless the DPI box is changed.
- Is A4 at 72 DPI 595 × 842 or 595 × 841?
- 595 × 842. The height works out at 841.89 and rounds up; a chart showing 841 cut the decimals off. A PDF describes the page as 595.28 × 841.89 points, so converters land on 842 too.
- Can I make A4 at 600 DPI here?
- No. 4961 × 7016 is close to 35 million pixels, over twice what a phone browser can build safely, so the tool declines it. 400 DPI (3307 × 4677) is the most it makes for a full sheet.
- How do I get A4 size in px for landscape?
- Make the width 297 and the height 210, keep mm and 300, and press Resize for 3508 × 2480. Tap px first and the boxes show those pixel values to type directly.
- Will my picture be stretched to fit the sheet?
- Not on the starting setting. “Crop to fill” keeps the proportions and cuts the overflow from two opposite edges; “Lock aspect ratio” keeps every pixel but leaves one side short; “Stretch” is the only choice that distorts and must be picked on purpose.