How do you check the authenticity of a US 100 dollar bill?

Answer 1

Checking for authenticity depends very much on the bill's date and design.

For current multi-color notes:

• There is a watermark on the right side, between the large "100" and the bill's edge.
• A security thread is to the left of Franklin's portrait. It glows pink under UV light.
• When the bill is tilted, the blue security ribbon shows small Liberty Bells that change to "100"; the inkwell disappears and reappears; and the large "100" changes from copper-colored to green
• The words ONE HUNDRED USA are microprinted along the edge of the quill.

• The reverse side is "polka-dotted" with tiny yellow "100"s

For 1990-series "big head" bills:

• There is a watermark on the right side, between the large "100" and the bill's edge.
• A security thread is to the left of Franklin's portrait. It glows red under UV light.
• The wording "USA 100" is repeated inside the "100" in the lower left corner. "The United States of America" appears as a line in the left lapel of Franklin's coat.
• The large "100" in the lower right corner changes color from green to black if the bill is tilted.

For pre 1990-series bills:

Older bills lack all of those more modern features above, so you have to go by appearance and feel:

• The paper will have tiny blue and red threads embedded in it. These should be visible under a strong light.
• The paper will have the same firm feel to it that more modern bills have.
• The denticles (teeth) around the seal on the front will be sharp and evenly spaced.
• The engraving lines of Ben Franklin's portrait will be sharp, and his image will appear to have depth, almost like a photo.