A jigger is a measuring tool; a shot glass is a drinking vessel. They both hold 1.5 ounces at their standard size, which is why people use the terms interchangeably, but they serve completely different purposes behind a bar. Understanding the distinction helps whether you’re following cocktail recipes at home or just trying to figure out how much alcohol you’re actually pouring.
Volume: Where They Overlap
In the United States, a standard shot is 1.5 fluid ounces, and the larger side of a standard jigger also holds 1.5 fluid ounces. That overlap is the main source of confusion. The National Institute on Alcohol Abuse and Alcoholism defines one standard drink as 1.5 ounces of distilled spirits at 40% alcohol, and specifically lists “a single jigger” of brandy or cognac as equivalent to a 1.5-ounce shot.
But shot glasses aren’t as standardized as you might think. They range from 1 to 2 ounces depending on the manufacturer, the bar, or the country. If you’re using one to measure ingredients for a cocktail, you might be off by half an ounce without realizing it. That’s a big deal in a drink with only three or four ingredients.
Purpose: Measuring vs. Drinking
This is the real difference. A jigger exists to measure and pour liquids accurately. It’s a bartending tool, like a scale in a kitchen. A shot glass exists so you can drink out of it. Professional bartenders don’t reach for a shot glass when building a cocktail. They use a jigger because it’s calibrated, consistent, and designed to pour cleanly.
Jiggers maintain their accuracy regardless of liquid temperature, flow rate, or viscosity. When tested against free pouring (counting in your head while you pour from the bottle), jiggers show a variance of about 0.05 ounces. Free pouring, even by trained bartenders, varies by around 0.25 ounces. That five-fold difference in precision is why craft cocktail bars worldwide treat jiggers as essential equipment.
Design: What a Jigger Looks Like
The classic jigger is an hourglass-shaped double cup made of stainless steel. One end is larger (1.5 ounces), and the other end is smaller, typically 0.75 or 1 ounce. The smaller side is sometimes called a “pony.” This double-ended design, patented in 1893 by a Chicago inventor named Cornelius Dungan, lets a bartender flip between two common pour sizes without picking up a second tool.
Most modern jiggers also have etched lines inside the cups marking intermediate volumes. A jigger marked at 2 ounces on one side and 1 ounce on the other might have interior lines at 0.25, 0.5, 0.75, 1.5, and 1.75 ounces, giving you access to nearly every measurement a recipe could call for.
Japanese Jiggers vs. Bell Jiggers
If you’re shopping for a jigger, you’ll encounter two main styles. Japanese jiggers are tall, narrow, and slightly conical. Their slim profile makes them more accurate because a small amount of liquid covers more vertical height, so it’s easier to see exactly where your pour lands. Many Japanese jiggers have interior markings every 5 milliliters. They’re the preferred tool in high-volume craft bars.
Bell jiggers are shorter and wider with a rounded, bell-like shape. They’re easier to pour from because of their wider lip, but that same width makes precision harder. The difference in liquid volume between a level pour and a slightly overfilled pour is much greater in a bell jigger than in a narrow Japanese one. Some bartenders have found that the interior measurement lines on bell jiggers can be inaccurate when checked against lab-grade measuring equipment, while Japanese jiggers tend to be spot-on.
How Sizes Change Outside the US
If you’re traveling or following a recipe from another country, be aware that “a shot” or “a measure” means different things in different places. In the UK, the standard legal spirit measure is 25 milliliters, which works out to roughly five-sixths of a US fluid ounce. That’s noticeably smaller than the American 1.5-ounce standard. Most of Europe, Asia, and the UK measure in milliliters rather than ounces, so jiggers sold in those markets are typically marked in metric units (30 ml, 45 ml, 60 ml) rather than fractions of an ounce.
When a British recipe calls for “one measure,” it means 25 ml. When an American recipe calls for “one shot” or “one jigger,” it means 1.5 ounces (about 44 ml). Confusing the two will leave your drink either too strong or too weak.
Which One Should You Use at Home
If you’re making cocktails, get a jigger. Even an inexpensive Japanese-style jigger with interior markings will dramatically improve your drinks compared to eyeballing pours or using a shot glass. The consistency matters: cocktail recipes are ratios, and getting those ratios right is the difference between a balanced drink and one that tastes like straight alcohol with a splash of something else.
If you’re just pouring shots to drink neat or share with friends, a shot glass is perfectly fine. It’s a serving vessel, and it does that job well. Just know that not all shot glasses hold 1.5 ounces. If you’re tracking your alcohol intake, it’s worth checking the actual capacity of yours. Fill it with water and pour the water into a measuring cup to know for sure.
Where the Word “Jigger” Comes From
The name traces back to sailing. A jiggermast is the smallest mast on a ship, and “jigger” came to refer to a sailor’s daily ration of rum and the small metal cup used to serve it. The term spread in the United States during the 19th century, when jiggers of whiskey were given to Irish immigrants building canals in New York. By the end of the 1800s, the hourglass measuring tool had been patented and the word had settled into its modern meaning.