This table shows you up to which recommended size you can print your digital images.  Because almost all digital cameras record images with a resolution of 72 dpi, we have calculated the respective print sizes for the dpi values listed.
Resolution guide:

150 dpi for good results.
300 dpi for excellent photo prints and professional prints.
Chart 1: Print sizes resulting from the photo's resolution
Default image resolution
in camera (72 dpi)		   Print (Width x height
at 150 dpi)		   Print (Width x height
at 300 dpi)
640 x 480 pixels   10.84 x 8.13 cm   5.42 x 4.06 cm
1024 x 768 pixels   17.34 x 13.00 cm   8.67 x 6.50 cm
1280 x 960 pixels   21.67 x 16.26 cm   10.84 x 8.13 cm
1600 x 1200 pixels   27.09 x 20.32 cm   13.55 x 10.16 cm
2048 x 1536 pixels   34.68 x 26.01 cm   17.34 x 13.00 cm
2288 x 1712 pixels   38.74 x 28.99 cm   19.37 x 14.49 cm
2560 x 1696 pixels   43.35 x 28.72 cm   21.67 x 14.36 cm
2560 x 1920 pixels   43.35 x 32.51 cm   21.67 x 16.26 cm
2816 x 2112 pixels   47.68 x 35.76 cm   23.84 x 17.88 cm
3200 x 2400 pixels   54.19 x 40.64 cm   27.09 x 20.32 cm
Chart 2: Pixel sizes for desired print sizes
Desired
paper format		   Necessary resolution
(at 150 dpi)		   Necessary resolution
(at 300 dpi)
13 x 9 cm   768 x 531 pixels   1535 x 1062 pixels
15 x 10 cm   886 x 591 pixels   1772 x 1182 pixels
18 x 13 cm   1063 x 768 pixels   2126 x 1535 pixels
Chart 3: As a comparison, standard formats are
Width x height   DIN format    
118.90 cm x 84.10 cm   A0    
84.10 cm x 59.40 cm   A1    
59.40 cm x 42.00 cm   A2    
42.00 cm x 29.70 cm   A3    
29.70 cm x 21.00 cm   A4    
21.00 cm x 14.80 cm   A5    
14.80 cm x 10.50 cm   A6    
10.5 cm x 7.40 cm   A7    
7.40 cm x 5.20 cm   A8    
5.20 cm x 3.70 cm   A9    
3.70 cm x 2.60 cm   A10    
 
...many photos can usually even be printed in good quality in larger formats. The resolution (given in dpi) can be viewed and changed in many image editing programs under the menu option “Picture Size”.