How many megapixels do you "need"?

When buying a digital camera don't become a sucker to megapixel marketing. Almost all digital cameras today have enough megapixels to satisfy the average consumer, however more megapixels don't always mean a better quality picture.

For photos you plan to only use on the Internet or send by e-mail, you can shoot at a lower resolution. If you know you want to print the photo, you'll need to shoot at a higher resolution.

Determining how much camera resolution you'll ultimately need for a print depends on the size of the print you want to make. The table listed below should help you decide on the proper resolution.

Source: http://forums.adoramapix.com/entries/228318-Resolution-and-image-quality

Camera

megapixels                   Approximate standard image resolution in pixels

2 megapixels                                     1600 x 1200

3 megapixels                                     2048 x 1536

4 megapixels                                     2274 x 1704

5 megapixels                                     2560 x 1920

6 megapixels                                     2816 x 2112

7 megapixels                                     3072 x 2304

8 megapixels                                     3456 x 2304

10 megapixels                                   3648 x 2736

12 megapixels                                   4288 x 2848

Print size      Optimal Resolution              Minimum Resolution

                        For good print quality            less optimal image quality

                        300px per inch                      100px per inch

3.5x5               1500 x 1050                          500 x 350

4x5                  1500 x 1200                          500 x 400

4x6                  1800 x 1200                          600 x 400

4x12                3600 x 1200                          1200 x 400

5x5                  1500 x 1500                          500 x 500

5x7                  2100 x 1500                          700 x 500

6x9                  2700 x 1800                          900 x 600

8x8                  2400 x 2400                          800 x 800

8x10                3000 x 2400                         1000 x 800

8.5x11            3300 x 2550                          1100 x 850

8x12                3600 x 2400                          1200 x 800

9x12                3600 x 2700                          1200 x 900

10x10             3000 x 3000                          1000 x 1000

11x14             4200 x 3300                          1400 x 1100

12x12             3600 x 3600                          1200 x 1200

12x18             5400 x 3600                          1800 x 1200

16x20              6000 x 4800                          2000 x1600   

20x30              9000 x 6000                          3000 x 2000

24x36              10800 x 7200                        3600 x 2400