what size photo can I print knowing the pixels of the picture?

Print quality is usually 300 dpi so your pixel dimensions would roughly only make 3x4.5" print in full quality.

to get a 24x32" poster at full quality you'd need a roughly 7200 x 9600 pixel image.

An 8 megapixel digital camera could only put out 100dpi at 24x36 which wouldn't look terrible at a few feet away, to get only 100dpi out of your image it could be about 9x14".

Maybe try running you image through something that turns it into halftone dots to blow it up, this site is really awesome for that and you can make posters out of whatever printer you have access to by piecing sheets together. http://homokaasu.org/rasterbator/

Hi Sally The Resize Wizard in PS7 was never the easiest thing to use so I used to ignore it and do it the other way around. In PS go to New, in the dialogue box that appears go to Presets>International Paper and from the Size drop down menu select A4. Set the Units to Inches. Now we set the resolution, there is a formula long used by professionals for this which is 1M of file size to 1 Inch of picture on the longest edge. This guarantees a good picture if you have enough pixels to start with. For this size a resolution of 206 works a treat. Note this is a minimum you can set it for any resolution higher, but and this is the important part, it can reduce picture quality with small files. Setting this value to the formula suggested gives a good picture with the minimum of interpolation, if your file is small setting the resolution higher means more interpolation, more 'invented' pixels. Whilst this dialogue box is open set the bit depth to 8bit and in the Advanced part set the Profile to sRGB. Press OK. This will open the new canvas in portrait if your picture is landscape go to Image>Rotate Canvas 90° (it doesn't matter which way). Open your image and drag it onto the canvas whilst holding the Shift Key down (this will plop it bang in the centre). Call up the Transform Tool (Ctrl + T) and holding down the shift Key (this time to maintain aspect ratio) drag the corner 'anchor points' out to cover the canvas. Press Enter, flatten and save. This is the file you send to the printer and it is guaranteed to give the best result as the number of pixels in the original allow. The resolution inside PS is PPI (pixels per inch) and this is what determine the size and quality the file will print. I see over and over on this site and others people trotting out 300 dpi as if this is some magic resolution for a decent print. DPI is dots per inch and is the PRINTERS resolution, in other words this is the resolution the printer is going to print your file at. It has NOTHING to do with print size and NOTHING to do with print quality, in fact its too good for an A4 and not good enough for a 6" X 4". Its an compromise value for quality vs print time and ink usage, its used by most print shops as kind of an industry standard. Chris

Put it on the computer and use the zoom.

This will enlarge the image and then you will see how big it can go before you can see the pixels.

If it shows pixels then the image is not suitable to be printed out large.

I do that all the time to see how far an image will take enlarging to. It's a quick and easy tester!