How can you tell if a US 100 dollar bill is real?

Answer 1

It depends very much on the bill's date, because newer bills have many more security features.

2009 and later series bills have a large "100" in the lower-right corner that features color-shifting ink. If you tilt the bill back and forth the color will change from copper to green. Similar ink is used for the bell on the inkwell. There are two security strips - a wide blue one to the right of Franklin's portrait, and a smaller strip embedded in the bill's paper to the left. The smaller strip glows under UV light. If you hold the bill up to a light, a watermark image of Franklin appears in the light-colored oval on the bill's right side.

1996 - 2003A bills have the small security thread, a watermark, and color-shifting ink. In addition the large 100 in the bill's lower left corner contains the phrase "USA 100" repeated in extremely small type that's usually visible only with a magnifying glass.

$100 bills printed before 1996 have very few security features on them. You can still look for the following:

• Hold the bill up to a light and look for tiny blue and red fibers embedded in the paper. (Note that there won't be a watermark like newer bills, though.)
• The paper will have a substantial feel to it, the same as modern bills.
• The denticles (teeth) on the Federal Reserve Seal will be sharp and uniform.
• The engraving of Franklin's face will be sharply-defined and appear almost 3D if viewed from a slight distance.