Bottle cap

Bottle Caps, also referred to as Caps for short, are the standard currency in Fallout, Fallout 3, Fallout: New Vegas, Fallout 4, Fallout 76, Fallout: Brotherhood of Steel and Fallout Shelter.

Background
Bottle Caps are used frequently as a currency because they are difficult to conterfeit and the number of caps existing are small. Bottle Caps are backed by water by the merchants of the Hub, and can be traded anywhere. An advertising campaign that the Nuka-Cola Corporation was testing out allowed the exchange of bottle caps with robotic vendors at the Whitespring Resort due to the release of Nuka-Cola Quantum.

Crimson Caravan Company, sought to control all bottle cap production and ensure that no one can mass produce them and inflate the currency. Controlling bottle cap presses also allows them to replace worn out and damaged bottle caps, keeping the pool of currency stable. Bottle Caps, NCR Dollars and Legion currency are all considered legal tender by the various caravan companies and on the New Vegas Strip. Mojave merchants also accept nonstandard variants, such as Sunset Sarsaparilla bottle caps.

Nuka-Cola Bottle Cap
Used as the basic form of currency throughout many of the American wastes. Their value differs throughout the games.

Bawls Bottle Cap
This special type of Bottle Cap is valued as 100 times that of a Nuka-Cola Bottle Cap.

Counterfeit Nuka-Cola Bottle Cap


They have no trade value and cannot be used for any monetary purpose.

Sunset Sarsaparilla Bottle Cap


This variant, taken off Sunset Sarsaparilla bottles, is used in the Mojave Wasteland alongside Nuka-Cola caps.

Sunset Sarsaparilla Star Bottle Cap


A rare variant of the Sunset Sarsaparilla bottle cap, featuring a blue star on the underside of the cap. These can be traded in to Festus at the Sunset Sarsaparilla Headquarters for a reward.

Alcohol bottle cap
In the Commonwealth, Nuka-Cola bottle caps aren't the only type accepted by merchants. Certain alcoholic beverages, like beer, which use crimp caps similar to Nuka-Cola, are also used.

Vim bottle cap
This variant, taken off Vim bottles, is used on The Island alongside Nuka-Cola caps.

Behind the scenes
Scott Campbell described how Bottle Caps were chosen as the currency due to being common.