Rats don’t actually eat money. They shred it. Despite viral photos of destroyed banknotes inside ATMs and safes, rats gain zero calories from currency and their digestive systems can’t process it. What looks like a meal is really a combination of two powerful biological drives: the need to grind down teeth that never stop growing, and the instinct to build insulated nests from soft, fibrous material.
Teeth That Never Stop Growing
A rat’s front teeth (incisors) grow continuously throughout its entire life, renewing completely every 40 to 50 days. Left unopposed, a single incisor can grow as much as 1 millimeter per day. That’s roughly an inch a month. If a rat doesn’t wear its teeth down through constant gnawing, the incisors overgrow, curve inward, and eventually make it impossible to eat. This condition is painful and, in the wild, fatal.
To keep their teeth at a functional length, rats chew on anything firm or fibrous they can find: wood, plastic, wiring, concrete, and yes, stacks of paper currency. The gnawing action grinds the upper and lower incisors against each other, wearing them down at roughly the same rate they grow. It’s not a choice. It’s a survival mechanism hardwired into every rodent’s behavior. A rat locked inside an ATM for 12 days with nothing but bundled banknotes will chew through those banknotes relentlessly, not because it’s hungry, but because it physically must.
Currency Makes Excellent Nesting Material
The second reason rats destroy money has nothing to do with teeth. Rats build nests from shredded soft materials to insulate themselves against heat loss. They’ll use fabric scraps, dried leaves, cardboard, insulation foam, or any paper they can tear into strips. Currency happens to be an ideal candidate.
U.S. banknotes are 75 percent cotton and 25 percent linen, woven with tiny red and blue synthetic fibers throughout. That blend makes currency far more durable than regular paper, but to a rat, it also makes it closer to cloth. The fibers shred into soft, flexible strips that hold warmth well. A rat encountering a pile of bills treats it the same way it would treat a cotton rag: it gnaws the material into smaller pieces and arranges them into a nest tailored to its thermal needs. Rodents in the wild use nests to create microclimates, curling into insulated pockets that minimize the body surface area exposed to cold air. Shredded currency fits that purpose perfectly.
Scent Plays a Role Too
Circulated banknotes carry traces of human skin oils, food residue, and organic compounds picked up from thousands of hands. Rats have an exceptionally sensitive sense of smell, and those faint organic traces can draw a rat toward stored cash the same way food packaging does. The rat investigates, finds a dense block of soft fibrous material, and its instincts take over. It’s worth noting that rats are true omnivores, eating seeds, fruits, vegetables, insects, and scavenged human food. But even with their remarkably broad diet, paper money isn’t on the menu. A rat that accidentally swallowed pieces of currency could get sick, since its digestive system is built to process organic food, not cotton-linen blends.
The ATM That Lost $17,600
The most famous case happened in 2018 in Tinsukia, a district in the Indian state of Assam. A State Bank of India ATM stopped working, and when technicians opened it 12 days later, they found banknotes worth more than 1.2 million rupees (about $17,600) shredded into confetti. Police determined that rats had entered the machine through a small hole meant for wiring. The rodents destroyed bundles of 2,000 and 500 rupee notes. Technicians managed to salvage another 1.7 million rupees that the rats hadn’t reached. Photos of the damage went viral, and the incident became a textbook example of why sealed cash storage needs rodent-proofing.
This wasn’t an isolated event. Banks and businesses across South and Southeast Asia regularly report rat damage to stored currency, and the problem isn’t limited to ATMs. Any enclosed space where cash sits undisturbed for days or weeks, from safes to cash registers to desk drawers, can attract a nesting rat.
Can You Recover Rat-Damaged Cash?
If rats have destroyed your money, you may still be able to get it replaced. The U.S. Bureau of Engraving and Printing runs a Mutilated Currency Redemption program that specifically lists rodent damage as a qualifying cause. You can receive full face value for a damaged bill if clearly more than 50 percent of the note is present along with enough of its security features to confirm it’s genuine. Even if 50 percent or less remains, you can still submit a claim if you can demonstrate that the missing portions were totally destroyed (by a rat, for instance) rather than separated and potentially spent elsewhere.
The Bureau accepts submissions by mail and now also accepts in-person deliveries at its Washington, D.C. office. The process involves packaging the remnants carefully, since further damage during shipping could make identification harder. The key is preserving whatever fragments you have rather than trying to tape bills back together, which can obscure the security features examiners need to verify.
How to Protect Stored Cash
Rats can squeeze through openings as small as a quarter, so any gap in a container, wall, or machine casing is a potential entry point. Metal cash boxes with tight seals are far more effective than wooden drawers or cardboard containers. For businesses, sealing cable entry points in ATMs and safes with steel wool or metal mesh eliminates the most common access routes. Keeping food waste away from cash storage areas also helps, since rats exploring for food are the ones most likely to discover and nest in stored bills.
If you find shredded currency with droppings nearby, the damage pattern itself tells you what happened. Rats leave irregular, rough-edged tears and tend to reduce paper to small strips or confetti-sized pieces. They rarely consume the material entirely, so most of the paper mass remains in or near the nest site, just in a very different shape than you left it.