If I recall correctly (& the older I get the less that seem to happen :-), the way you figure out render size is by multiplying the DPI you plan to print at by the finished picture size... if you're printing at 300dpi you'd figger it as 300X8=2400 300X10=3000 so to get an 8X10 printed at 300dpi the render would be 2400X3000