A4, US Letter or original size
Image en PDF editorial team ·
The page size decides the size of the paper, not the quality of the image. Above all it determines whether the image is enlarged, reduced or left at its own dimension.
A4 and US Letter: pages of fixed size
A4 measures 210 × 297 mm and US Letter 216 × 279 mm. Both give every page the same dimension, which is essential for printing a document or sharing one with a predictable layout.
Each image is reduced or enlarged to fit the usable area without being distorted. A panoramic image therefore leaves white space above and below; that is the expected behaviour of the whole-image mode.
Original size follows the image
With the original size, each page takes the physical dimension of its image. The converter reads the resolution declared in the file (most often pixels per metre for a PNG, points per inch for a JPEG) and uses 96 PPI when the file declares none.
One consequence to know: raising that value later in another program creates no detail. An image 1400 pixels wide at 96 PPI measures about 370 mm; the same image declared at 300 PPI would measure 118 mm, with exactly the same pixels.
Margins: room, not a crop
Margins reduce the area where the image can be placed. In whole-image mode they never cut the image: they simply leave a white border. The offered values are 0 mm, 5 mm and 12 mm, and a custom value is accepted up to 50 mm.
Cropping only happens with the fill-the-page mode, which cuts the overflowing edges. The preview then shows exactly the part that is kept.
Choosing by use
To print a document, or to send it to someone who will print it, A4 (or US Letter depending on the country) is the safest default. To archive screenshots or attach diagrams, the original size avoids any unnecessary enlargement.