What size does my image need to be to print well?

It can all become very confusing... dpi... pixels.. mega what?

When it comes to printing your photos, there are a few measurements/units you can use to check the file is the right size for printing.  Some units relate to how the image displays on a computer monitor while others relate to how your image will look when it is printed.  Here are the main units explained...

PIXELS/DOTS - ppi/dpi

A pixel is represented by a tiny square on a computer monitor.  When a camera takes an image, it records a certain number of pixels - the more pixels, the more detail, the higher the resolution.  The number of pixels your image has is measured by the pixels per inch displayed (ppi).  This is not to be confused with dots per inch (dpi) which refers to the number of printed dots contained within one inch of an image printed by a printer.  Often printers will use more than one dot to create a pixel so the dpi is often higher than the ppi.

So, how many ppi and dpi do you need to your image to print nicely?  Well, it depends on the type of paper and the printer but generally speaking ... 300ppi printed at 300dpi will give you a good result.


Digital files are also measured in terms of size and information.  A bit is the smallest unit of information. A byte is the next smallest unit, and is equal to 8 bits. A kilobyte (kb) is a thousand bytes and a megabyte (mb) is a million bytes.

For an image to print well at 300ppi,the minimum size is 2mb.  Following are some good guidelines...

Print Size 300ppi
4" x 6" or 102mm x 152mm 2.2mb
5" x 7" or 127mm x 178mm 3.2mb
6" x 8" or 152mm x 203mm 4.4mb
8" x 10" or 203mm x 254mm 7.2mb
A4 or 210mm x 297mm 8.0mb
A3 or 297mm x 420mm 17.6mb
A2 or 420mm x 594mm 28.8mb
A1 or 594mm x 840mm 77.5mb
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