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Choosing the right file size for stock photos

Assorted ten round different colors various sizes diameters balls cricket golf pool tennis football soccer beachball squash - AGTGRC ©
© Dinodia Images / AlamyBefore you download your stock photos, it's important that you check that the image/s you have chosen will meet the needs of the job in hand. To do this, you will need to take two factors relating to the final output into account:

The dimensions indicate the size that your image will appear when printed, whilst the resolution indicates how much detail will be included in every inch printed. You always need to consider both the size that the image will be reproduced (shown in inches and millimeters below) and the print resolution (shown as dpi) that will be used.

For book and magazine printing, the print resolution for your stock photos typically needs to be 300dpi and above. Large format prints, such as billboards, are usually printed at lower resolutions of under 150dpi (the image is less detailed because it is viewed from farther away) although it's worth checking with your print department before you start. If they require a higher resolution, Alamy can help you by applying interpolation or upsizing. However, once you've received the stock photo, whilst you can shrink it, it cannot be easily expanded without losing quality.

Here are some standard uses of stock photos, showing dimensions, dpi and file size required:


© Juniors Bildarchiv / Alamy

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Paper sizes

A Series

Used for general printing, such as stationery and publications. The most common sizes are A4 for stationery and documents, A5 for books, A6 for postcards.

Approximate file sizes for A-Series paper
Size Millimeters MB Approx Inches
A0 841 x 1189 > 70* 33 1/8 x 46 3/4
A1 594 x 841 > 70* 23 3/8 x 33 1/8
A2 420 x 594 > 70* 16 1/2 x 23 3/8
A3 420 x 297 49 - 70 16 1/2 x 11 3/4
A4 297 x 210 25 - 48 8 1/4 x 11 3/4
A5 210 x 148 13 - 24 5 7/8 x 8 1/4
A6 105 x 148 3 - 12 4 1/8 x 5 7/8
* Or use interpolation

B Series

Used for bigger jobs like posters.

Approximate file sizes for B-Series paper
Size Millimeters MB Approx Inches
B0 1000 x 1414 > 70* 39 3/8 x 55 5/8
B1 707 x 1000 > 70* 27 7/8 x 39 3/8
B2 500 x 707 > 70* 19 5/8 x 27 7/8
B3 353 x 500 49 - 70 13 7/8 x 19 5/8
B4 250 x 353 25 - 48 9 7/8 x 13 7/8
B5 176 x 250 13 - 25 7 x 9 7/8
B6 125 x 176 3 - 12 4 7/8 x 7
* Or use interpolation

C Series

Used for envelopes, designed to take A series paper. For example C4 for A4, C5 for A5 and so on. DL envelopes take A4 sheets folded twice.

Approximate file sizes for C-Series paper
Size Millimeters MB Approx Inches
C0 917 x 1297 > 70* 39 3/8 x 51
C1 648 x 917 > 70* 25 1/2 x 36 1/8
C2 458 x 648 > 70* 18 x 25 1/2
C3 324 x 458 49 - 70 12 3/4 x 18
C4 229 x 324 25 - 48 9 x 12 3/4
C5 162 x 229 13 - 24 6 3/8 x 9
C6 114 x 162 3 - 12 4 1/2 x 6 3/8
C7 81 x 114 3 - 12 3 1/4 x 4 1/2
C8 57 x 81 3 - 12 2 1/4 x 3 1/4
DL 110 x 220 13 - 48 4 3/8 x 8 5/8
* Or use interpolation
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