You can determine both the image magnification and the size of a fossil specimen if an object of known size is included in the image. In following figure , the penny has a known diameter of 0.75 in. However, in this image the penny measures only 0.5 inch across. Now you know that the image is smaller than its actual size. In fact, the magnification is 0.67 times its actual size.

Magnification = diameter of the penny in the image/actual diameter of a penny

Magnification = 0.50 inch/0.75 inch

Magnification = 0.673

Now estimate the actual length of the leaf fossil using the penny for scale. Use the following calculation.