How to calculate print sizes

Hi my friends. Today I want to tell, for those who do not know already how to calculate maximum print sizes, depending on the size of the digital image you produce. Bear in mind that the standard "ppi" - pixels per inch - for "photo quality" prints, is 300 ppi's. Also a big discussion is being held in several foruns I participate and also talking with professional printers, wether a file for printing shall be a TIFF or a HIGH QUALITY JPEG. But first for print sizes. A megapixel is 1 million pixels.It's an area measurement like square feet.
For instance,a 8 megapixel camera produces images that are 3266 x 2450* pixels.
If you multiply 3266 by 2450, you get 8,001,700 or 8 million pixels.
To find the largest photo quality image you can print, simply divide each dimension by 300:
3266 / 300 = 10.89 inches
2450 / 300 = 8.17 inches
If you are not publishing your images in a book or magazine, and you're just making prints for yourself or your friends, you can "cheat". Good quality inkjet printers can make a nice looking print at 250 or 200ppi. At 200ppi, the maximum print size becomes:
3266 / 200 = 16.33 inches
2450 / 200 = 12.25 inches
If you know how to use image editing software like Photoshop, you can "cheat" even more by increasing the image size, and even doubling the number of pixels in the image. The quality of the camera and lense becomes more important at this point bacause any loss of detail or sharpness is magnified. If an image is enlarged too much in this manner, it will look "fuzzy" or "pixelated".
As for TIFF vs HQJPEG's, if I would print at home for a "true photo quality" printing, I would use always a TIFF file, as all the image information is not compressed or lost. However, I learnt that when printing outside, in a professional printing lab, an HQuality JPEG ( 12 compression number in Photoshop, the less compressed one )do make EXCELLENT results. However also learnt that if we want to publish our captures in a magazine or a book, TIFF is allways the best option. Hope this info was helpfull to all of you. GT.