Learn How to Spot Authentic One Hundred Dollar Bills

Understanding the Security Features of U.S. $100 Bills

The United States $100 bill contains multiple security features designed to prevent counterfeiting. The Bureau of Engraving and Printing, a division of the U.S. Department of the Treasury, continuously updates these features to stay ahead of counterfeiters. Learning about these features helps you identify genuine currency in everyday transactions.

Modern $100 bills feature a security thread embedded within the paper itself. This thread runs vertically from top to bottom on the left side of the bill when held up to light. The thread contains text that reads "USA 100" and appears in a specific color. On bills printed after 2013, this thread glows pink under ultraviolet light. This feature cannot be easily replicated because it requires specialized equipment and materials used only by the government.

The paper composition itself is a security measure. U.S. currency is not made from wood pulp like regular paper. Instead, it consists of 75% cotton and 25% linen. This specific blend gives genuine bills a distinctive texture and durability. Counterfeit bills made on regular paper feel different and deteriorate more quickly. The cotton-linen combination also allows the bills to survive washing and normal wear better than paper alternatives.

Color-shifting ink represents another important security element on modern $100 bills. Located in the lower right corner, a numeral "100" appears in ink that changes color when you tilt the bill. Under normal light, it appears copper or green, but when tilted, it shifts to green or blue. Creating this effect requires technology that counterfeiters struggle to replicate accurately.

Practical Takeaway: Start by holding any $100 bill up to light and looking for the security thread on the left side. Feel the texture of the bill between your fingers. Practice distinguishing genuine bills from counterfeit ones by examining these features regularly, so you develop familiarity with what authentic currency should feel and look like.

Examining Watermarks and Their Placement

Watermarks on $100 bills serve as a critical authentication tool that most people overlook. A watermark is an image created during the paper manufacturing process, appearing lighter or darker than the surrounding paper. On $100 bills, the watermark shows a portrait that matches the historical figure featured on the bill—Benjamin Franklin.

To view the watermark, hold the bill up to a light source such as a lamp, window, or flashlight. The watermark should appear on the right side of the bill, positioned where the numeral "100" also appears. The watermark shows Benjamin Franklin's profile and is visible from both sides of the bill. On genuine currency, the watermark appears as a three-dimensional image that matches the main portrait in terms of detail and quality. The watermark should be clear and distinct, not blurry or faded.

The positioning of the watermark is specific and consistent on all genuine $100 bills. It always appears in the same location relative to the bill's borders and other design elements. Counterfeiters often struggle with watermark placement because creating a watermark requires specialized equipment that operates during paper production. Simply printing an image onto regular paper cannot replicate a true watermark. The watermark on a genuine bill appears integrated into the paper itself, not as an overlay.

Different decades of $100 bills may show slight variations in watermark clarity based on when they were printed. Bills printed in the 1990s may show less distinct watermarks than those printed in the 2000s and beyond. However, the watermark should always be visible when held to light. If you cannot see a watermark at all, or if it appears only on one side of the bill, this indicates a counterfeit.

Practical Takeaway: Practice viewing watermarks by holding $100 bills up to light in various environments—near windows, under desk lamps, and with flashlights. Notice how the watermark appears from both sides of the bill. This practice builds your ability to quickly confirm a bill's authenticity during routine transactions.

Identifying Microprinting and Fine-Line Patterns

Microprinting appears on multiple locations of the $100 bill and represents one of the most difficult features for counterfeiters to reproduce. Microprinting consists of extremely small text that is only visible when examined with magnification, typically requiring a magnifying glass or jeweler's loupe. This technique requires specialized printing equipment and precision that counterfeiters rarely possess.

On the $100 bill, microprinting appears on Benjamin Franklin's collar area. When examined under magnification, small text reading "THE UNITED STATES OF AMERICA" becomes visible. The size of this text is so small that it appears as fine lines or shading to the naked eye. If you attempt to photocopy or scan a genuine $100 bill, the microprinting does not reproduce clearly, appearing as a blurry gray area instead. This is by design—it serves as a test for counterfeiting equipment.

Fine-line patterns fill the background areas of the $100 bill, particularly around the borders and behind the portraits. These patterns consist of incredibly thin, closely-spaced lines that create visual texture. The precision required to print these lines is exceptional. Counterfeit bills frequently show broken or uneven lines in these areas because the printing equipment used lacks the necessary precision. When examined closely, genuine bills show consistent, unbroken fine lines throughout these areas.

The number "100" on the bill also contains microprinting elements. Examining this numeral with a magnifying glass reveals additional security details. The level of detail in these numbers far exceeds what standard printing equipment can produce. Counterfeiters attempting to recreate these elements often produce blurry or incomplete results. Professional currency examiners use magnification as one of the primary tools for identifying counterfeits because these details simply cannot be faked with consumer-grade equipment.

Practical Takeaway: Obtain an inexpensive magnifying glass (available at hardware stores for $5-15) and regularly examine the microprinting on $100 bills. Look particularly at Franklin's collar area and the "100" numerals. Familiarize yourself with what clear, precise microprinting looks like so you can spot blurry or incomplete microprinting that indicates counterfeiting.

Checking the Serial Numbers and Ink Quality

Serial numbers on $100 bills follow specific patterns and are printed in specialized inks that exhibit particular characteristics. Each bill has a unique serial number printed twice—once on the left side and once on the right side of the bill. These numbers consist of one letter followed by eight digits, followed by another letter. The format and positioning are standardized across all genuine bills.

The ink used for printing serial numbers has special properties that regular ink does not possess. When you rub your finger across a serial number on a genuine bill, the ink should feel raised and textured, not smooth. This raised printing, called intaglio printing, creates a tactile quality that counterfeiters struggle to replicate. The ink should also resist fading and smudging. If serial numbers appear flat to the touch or if the ink smudges easily when rubbed, these are signs of counterfeiting.

Serial numbers follow specific color standards depending on the series and printing date of the bill. On $100 bills printed after 1996, serial numbers appear in green or black ink depending on which Federal Reserve Bank printed them. The specific shade of green or black used is standardized. If serial numbers appear in unusual colors—such as red, blue, or brown—this indicates a counterfeit. The numbers should also be evenly spaced and aligned straight, not tilted or misaligned.

The quality and consistency of all printed elements on genuine bills reflect high-quality printing processes. The ink density should be uniform across the entire bill. No areas should show excessive ink pooling or dry spots where ink is missing. When examining the overall appearance, genuine bills look crisp and professional. Counterfeits often show variations in ink quality—some areas appear too dark while others appear faded. These inconsistencies result from using different printing equipment and techniques than those employed by the U.S. government.

Practical Takeaway: Gently run your fingernail across the serial numbers on $100 bills you receive. You should feel a slight raised texture. Examine the serial numbers under good lighting to confirm they are evenly spaced and aligned straight. Check that the ink color matches standard colors (green or black), and verify that both serial numbers on the bill are identical.

Understanding the Intaglio