A jerrycan or jerrican (also styled jerry can or jerri can) is a fuel container made from pressed steel (and more recently, high density polyethylene). It was designed in Germany in the 1930s for military use to hold 20 litres (4.4 imp gal; 5.3 US gal) of fuel or water, and saw widespread use by both Germany and the Allies during the Second World War.

The development of the jerrycan was a significant improvement on earlier designs, which required tools and funnels to use, and it contained many innovative features for convenience of use and robustness. Today similar designs are used worldwide for fuel and water containers, in both military and civilian contexts.

The name of the jerrycan refers to its German origins, Jerry being slang for Germans. The design was reverse engineered and subsequently copied, with minor modifications, by the Allies during the Second World War.

The Wehrmacht-Einheitskanister ("Armed forces standard canister"), as it was known in Germany, was first developed in 1937 by the Müller engineering firm in Schwelm to a design by their chief engineer Vinzenz Grünvogel. A similar design was used in 1936 during the Spanish Civil War, where they had a company logo for Ambi-Budd Presswerk GmbH. Among others, the Wehrmacht had specified that a soldier should be able to carry either two full containers or four empty ones, which is the reason the triple handles were fitted. To achieve the required filling and draining speed, it was fitted with a large spout and flip top closure. A hole in the closure retainer made it possible to fit a securing pin or wire with a lead seal. The rectangular shape made it stackable. The recessed welded seam stiffened the container and protected the seam from impact damage. The indentations ensured a full can would not be severely damaged when falling from a vehicle, while a dip coat of paint on the inside protected it from corrosion.

By 1939 the German military had thousands of such cans stockpiled in anticipation of war. Motorised troops were issued the cans with lengths of rubber hose in order to siphon fuel from any available source, a way to aid their rapid invasion of Poland at the start of the Second World War.

In 1939, American engineer Paul Pleiss had built a vehicle to journey to India with his German colleague. After building the car, they realised they did not have any storage for emergency water. The German engineer had access to the stockpile of jerrycans at Berlin Tempelhof Airport and managed to take three of them. The German engineer also gave Pleiss complete specifications for the manufacture of the can. Pleiss continued on to Calcutta, put his car in storage, and flew back to Philadelphia, where he told American military officials about the can. He could raise no interest. Without a sample, he realised he could not get anywhere. He eventually shipped the car to New York by a roundabout method, and sent a can to Washington. The War Department decided instead to use World War I ten-US-gallon (38 L; 8.3 imp gal) cans with two screw closures, which required both a spanner and funnel for pouring.

The one jerrycan in American possession was sent to Camp Holabird, Maryland, where it was redesigned. The new design retained the handles, size and shape, but is most easily distinguishable from the German original by the simplified 'X' - stiffening indentations in the sides of the can. The US can could be stacked interchangeably with German or British cans. The German recessed welded seam was replaced with rolled seams which were prone to leakage. For fuel cans, the lining was removed and a spanner and funnel were required. A similar water can was also adopted, with a flip-top lid and enamel lining.

The US-designed jerrycan was widely used by US Army and Marine Corps units. In all overseas theaters, fuel and other petroleum products represented about 50% of all supply needs, measured by weight. In the European Theatre of Operations alone, over 19 million were required to support US forces by May 1945.