The available image detail also determines the largest size print you can obtain from your image. The following chart, adapted from the help screens at ClubPhoto and then augmented, shows the available size prints they offer, and also the minimum resolution they recommend. I added the Min MegaPixels column to their chart, which shows the minimum MegaPixel rating for the camera to produce their resolution, before being cropped to the aspect ratio of the print, and which is derived exactly from their Min Resolution column. I'm not sure that all their resolutions are consistently related to the Print Size, and that may have something to do with the type of equipment they have, their expectations of viewing distance for different size products, and/or their opinions of customer satisfaction with different size products.

Personally, I'd recommend about twice their minimum resolutions. Note that twice the resolution would become 4 times the minimum MegaPixels, becausewidth and height get multiplied together to obtain MegaPixels. Even more MegaPixels are better yet, because that allows the image to be cropped in all directions before being printed, and still have enough image detail remaining to produce a decent print.

It is good to note that if you want complete control over what gets printed, you should pre-crop your pictures to the exact aspect ratio you wish to print, and leave a bit of border around the desired image, to allow the print vendor to crop just a little in all directions to be sure they leave no white edges on the picture itself, and to allow for a bit of obscuring of the edge of the print when matting or framing.

Product | Min. Resolution | Min MegaPixels | Print Size |

4 x D Digital Reprint(s) | 640 x 480 | 0.3 (640x480) | 4 x 5.33 |

4 x 6" | 640 x 427 | 0.3 (640x480) | 4 x 6 |

5 x 7 | 800 x 571 | 0.5 (640x480) | 5 x 7 |

3.5 x 5" | 640 x 448 | 0.3 (640x480) | 3.5 x 5 |

8 x 10 | 1024 x 819 | 1.2 (1280x960) | 8 x 10 |

4 Wallets 2 x 3" | 200 x 142 | 0.04 (320x240) | 2 x 3" |

8 x 12 | 1280 x 854 | 1.2 (1280x960) | 8 x 12 |

Poster 12 x 18" | 876 x 580 | 0.75 (1024x768) | 12 x 18 |

Poster 10 x 13" | 1536 x 1182 | 1.8 (1576x1182) | 10 x 13 |

Poster 16 x 20" | 1024 x 728 | 0.75 (1024x768) | 16 x 20 |

Poster 11 x 14" | 1536 x 1209 | 1.9 (1612x1209) | 11 x 14 |

Poster 16 x 24" | 1320 x 728 | 1.25 (1320x990) | 16 x 24 |

Poster 20 x 20" | 1024 x 1024 | 1.33 (1365x1024) | 20 x 20 |

Poster 20 x 24" | 1320 x 1024 | 1.33 (1365x1024) | 20 x 24 |

Poster 18 x 24" | 1320 x 876 | 1.25 (1320x990) | 18 x 24 |

Poster 20 x 30" | 1800 x 1200 | 2.3 (1800x1350) | 20 x 30 |

Poster 24 x 36" | 2400 x 1600 | 4.1 (2400x1800) | 24 x 36 |

Poster 30 x 40" | 2600 x 2100 | 5.6 (2800x2100) | 30 x 40 |