Hello, I am asking how to calculate the area of a cell from pixels to mm.
total pixels in image- 577,918 pix
pixels in cell- 17128
diameter of microscope image- 4mm
magnification- 40x
please help, thank you
48582

Try this. There are a number of other online converters.
mm to px Converter, Chart -- EndMemo (http://endmemo.com/sconvert/millimeterpixel.php)

Thank for this but I need to know how to do the physical calculations. Can you help me with that :)

17128 pixels in a cell. Then use the table I gave you.