You’ve probably held one today. Or maybe you’re lucky enough to have a stack of them tucked away. The Benjamin. The C-note. Whatever you call it, the $100 bill is the most frequently circulated—and most frequently counterfeited—denomination of U.S. currency outside the country.
It’s heavy lifting for a piece of paper. Honestly, it isn't even paper; it's a blend of 75% cotton and 25% linen. That's why it survives the washing machine when your jeans go in for a scrub. But the real magic isn't in the fabric. It’s in the high-tech, borderline sci-fi US 100 dollar bill security features that the Bureau of Engraving and Printing (BEP) has spent decades perfecting.
Most people just look for the watermark. Big mistake. While the watermark is great, modern counterfeiters have gotten scary good at bleaching lower-denomination bills and printing a hundred over them. If you only look at the ghost of Ben Franklin, you might get burned.
The blue ribbon that actually moves
Take a close look at that 3D Security Ribbon. It’s the thick, blue vertical stripe woven into the center of the bill. Not printed on it. Woven through it. If you see a bill where the blue stripe looks like it’s just sitting on the surface, give it back. It’s fake.
When you tilt the note back and forth, something weird happens. The little bells inside the ribbon change to 100s. If you move the bill side to side, they move up and down. If you move the bill up and down, they move side to side. It feels counterintuitive because it is. This uses hundreds of thousands of micro-lenses to create the illusion of movement. It is incredibly expensive to replicate, which is why it's the first thing professional bank tellers check.
That copper ink isn't just for show
Next to Franklin’s shoulder, there’s an inkwell. Inside that inkwell is a bell. At first glance, it looks like a simple copper graphic. But tilt it.
The bell changes color from copper to green. This shift makes the bell appear and disappear within the copper inkwell. This is known as Color-Shifting Ink. You'll find the same tech on the large "100" in the bottom right corner of the note’s front.
Counterfeiters hate this stuff. Genuine color-shifting ink is metallic and crisp. Fakes often look dull, or the color shift is "chunky" rather than a smooth, liquid transition. If it doesn't "flip" color instantly, it’s a red flag.
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The "secret" texture of Ben’s coat
Run your fingernail across Benjamin Franklin’s shoulder. Seriously, do it right now if you have a bill.
You should feel a distinct, rough texture. This is the result of intaglio printing. The paper is forced into recessed plates under massive pressure, creating a raised ink effect that you can actually feel. Most desktop printers—even the $5,000 ones—apply ink flatly. If Franklin’s jacket feels smooth like a glossy magazine, you’re holding a counterfeit.
The Fed spent a lot of time on the portrait. The engraving is so fine that the lines are almost microscopic. Look at the eyes. On a real bill, they are sharp, clear, and look "alive." On a fake, the eyes often look muddy or blurred because the printer couldn't handle the resolution.
Finding the hidden messages
Microprinting is another one of those US 100 dollar bill security features that most people never notice because, well, it’s tiny. You basically need a magnifying glass or a very good phone camera to see it.
- Look at the collar of Franklin’s jacket. You’ll see "THE UNITED STATES OF AMERICA" in tiny letters.
- Check the space around the watermark. There is "USA 100" printed there.
- Look along the golden quill. More tiny words.
If these letters look like a solid line or a series of dots, the bill is a dud. Real microprinting is legible under magnification, no matter how small it gets.
The glow-in-the-dark test
If you work in retail, you’ve seen the UV lamps. When you put a real $100 bill under ultraviolet light, a vertical security thread glows pink. It’s located to the left of the portrait.
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This thread has "USA" and "100" printed on it in an alternating pattern. It’s visible from both sides of the note. Most importantly, it glows a very specific shade of pink. Counterfeiters sometimes try to bleach $5 bills (which have a blue glow) or $10 bills (which glow orange) to print $100s on them. If that strip glows any color other than pink, the bill is a "fraken-note."
Why the "Series 2009" and later matters
The "New 100" was actually delayed for years. It was supposed to come out sooner, but they had "creasing" issues at the printing press. It finally hit the streets in 2013. This version is the gold standard of currency security.
If you come across an older bill—the ones with the smaller portraits—they are still legal tender. However, they lack the 3D ribbon and the disappearing bell. Because those older bills are easier to fake, many businesses are hesitant to take them. If you’re traveling abroad, specifically in places like Southeast Asia or the Middle East, many money changers will flat-out refuse any $100 bill that isn't the "blue" 2009 series or later.
Common myths about fake money
People think the "counterfeit pen" is foolproof. It’s not.
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Those pens react to starch. Real currency paper is starch-free, so the pen stays yellow. If a counterfeiter prints a fake on high-quality starch-free paper, or even just sprays a fake bill with a specific chemical, the pen will "pass" it. Never rely solely on the pen.
Another myth: "If the ink rubs off, it's fake."
Actually, real bills can sometimes smudge if they are brand new and you rub them hard against white paper. It's not a definitive test. Stick to the 3D ribbon and the raised printing.
Summary of what to check right now
Don't overcomplicate it. If someone hands you a hundred, do these three things:
- Feel it: Rub the shoulder. It must be rough.
- Tilt it: Watch the blue ribbon and the copper bell. They must move and change color.
- Hold it to light: Look for the watermark on the right and the security thread on the left.
If any of those feel "off," it probably is. The U.S. Secret Service estimates that about $147 million in counterfeit currency is in circulation. Don't let your wallet be the place it ends up.
Your Actionable Checklist
- Invest in a 10x jeweler's loupe: If you handle a lot of cash, this is the only way to truly see the microprinting.
- Download the "Cash Assist" app: Created by the U.S. government, it uses your camera to identify security features in real-time.
- Check the serial numbers: If you have two bills with the exact same serial number, at least one (and likely both) are fake.
- Report it: If you get a fake, do not try to spend it. That’s a felony. Take it to the local police or the nearest bank. They won't give you a real $100 in exchange, but they will take the fake out of circulation and report it to the Secret Service.