The number 3 holds powerful significance and symbolism in cultures around the world, from ancient Greek philosophy to religion and numerology. For some it’s simply a lucky number. But for others it possesses more spiritual weight, representing the Holy Trinity: the cycle of birth, life, and death; or the lifespan of past, present, and future.

A generation weaned on Saturday morning cartoons will no doubt recall the magnitude of 3 when singing along to the 1973 “Schoolhouse Rock” educational earworm, “Three Is a Magic Number,” which the hip-hop group De La Soul later sampled on their track “The Magic Number.” Continuing the chain, “The Magic Number” also played over the end credits of 2021’s “Spider-Man: No Way Home,” the multiverse-spanning third film in the most recent Spider-Man trilogy that brought Tom Holland, Andrew Garfield, and Toby Maguire’s three, era-spanning web-slingers together in the same timeline.

Trying to make sense of superhero timeline shenanigans might have you reaching for a drink, at which point you’ll likely also stumble upon the magic number. In the world of cocktails, the number 3 is less about harmony, wisdom, and understanding, and more about balance. And if you look at the modern serve of many classic cocktails, most — not all, but many — are composed of 3 total ounces of base ingredients.

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Is this a happy coincidence or further proof that 3 does, indeed, hold some extraordinary influential force beyond mathematics?

The Universal Theory of 3

The theory of 3 holds true in most current takes on classics like the Manhattan, Martini, Corpse Reviver No. 2, and Last Word, a pre-Prohibition drink composed of equal parts gin, green Chartreuse, maraschino liqueur, and lime juice that was reincarnated in 2004 by Seattle bartender Murray Stenson. Sam Ross took the Last Word’s 4 x ¾-ounce formula to new heights with his Paper Plane, a mix of bourbon, Amaro Nonino Quintessentia, Aperol, and lemon juice. That modern classic would then inspire multiple other riffs, most notably the Naked and Famous and Final Ward.

As for why we now think of modern cocktails as 3-ounce builds, Greg Boehm, the founder of barware company Cocktail Kingdom and co-owner of multiple bars, including New York’s Katana Kitten and Superbueno, believes that all roads lead back to David A. Embury’s 1948 book “The Fine Art of Mixing Drinks.”

“I think that was the biggest influence that I remember from back then because ‘The Fine Art of Mixing Drinks’ has been seen as the quintessential book on cocktail-making technique, and I think a lot of people took that to be the gospel,” he says.

Boehm notes that Embury’s book was a resource behind the bar in the early days of the cocktail renaissance with influential bartenders like Dick Bradsell in the U.K. and Audrey Saunders in New York. In the book, Embury describes the average cocktail glass ranging from 2 to 3 ½ ounces, with a cocktail itself averaging 2–2 ½ ounces. The modern adoption resulted in a return to smaller cocktails than the ones being poured in the ’70s to the ’90s, ultimately leaning toward 3 ounces of base ingredients for new takes on classics as the cocktail revival’s influence spread.

Looking back at his first two books, award-winning author and cocktail historian David Wondrich, editor of “The Oxford Companion to Spirits & Cocktails,” recalls that with “Esquire Drinks” (2004) the base recipes were inconsistent, coming in at 3, 4, and sometimes 5 ounces. But with “Killer Cocktails” (2005) — a quirky hands-free, stand-up, step-by-step guidebook on mixing drinks — the adaptations of newly rediscovered classics all hovered around 3 ounces.

 “Three ingredients are easier for the bartender to remember, plus three ingredients fit on one line of a menu, and three ingredients take up less space in the well you’ll need to store them for service in. The economy of three matters!”

“When you’re teaching cocktails, you can’t ask people to memorize recipes that are all different sizes for no reason,” Wondrich says. In 2006, when he was writing the first bar manual for Bar 5-Day, the annual extensive (and intensive) educational program on spirits and craft cocktails, Wondrich relied on a 3-ounce baseline for consistency and ease when measuring with an American-sized jigger. “You can divide up three easily using standard jigger denominations. They’re all factors of 3 ounces and that kind of detail is important when you’re actually mixing drinks,” he says.

When you take a classic like the Manhattan, the standard spec of 2 ounces of bourbon or rye and 1 ounce of sweet vermouth carries on the rule of 3, even if you’re splitting your whiskey base or vermouth specs. As for the Martini, bartenders are accustomed to the many particular demands and personal preferences from guests. Beyond the call for gin or vodka, whether it’s a 50/50 (1 ½:1 ½) or dry (2 ½:½), that 3-ounce backbone stands up to customization.

Jim Meehan, educator, advisor, and author of “Meehan’s Bartender Manual,” also recognizes the practical value of 3 — both in ounces and number of ingredients. “Three ingredients are easier for the bartender to remember, plus three ingredients fit on one line of a menu, and three ingredients take up less space in the well you’ll need to store them for service in,” he says. “The economy of three matters!”

As the author of “3-Ingredient Cocktails,” Robert Simonson says one of the main factors in a drink becoming a modern classic is by “being simple and easily replicable,” and adds that as originally conceived, “three is the fewest number of ingredients you can use to create a cocktail.”

Size Matters

While the contemporary metal jigger was first adopted by bartenders as early as the 1870s, cocktails featured in older bar books often call for ingredients to be measured by the dash, glass, pony, gill, teaspoon, or wine glass. The jigger brought precision to recipes, but glassware also played a role in determining the ultimate size of a drink.

Vintage glassware was typically much smaller than what we’re used to now but could still easily manage a 4–5 ounce drink. “When you’re looking at old cocktail and bar books it’s extremely, extremely inconsistent,” Boehm says. “In the 1936 book ‘The Barman’s Mentor’ by Eddie Woelke, he actually mentions the volume of glasses you should use and mentions several sizes, including a 3-ounce, low-stem cocktail as well as 5-ounce Clover Club glass. There were mostly 4-ounce glasses through the 1800s and then at Prohibition and post-Prohibition they’re getting up to 5 ounces.”

“The return to 3-ounce cocktails at the turn of the century was nothing more than a long-in-coming correction. The huge cocktails of the ’80s and ’90s were an aberration.”

Wondrich adds there wasn’t much of an “orthodoxy” of universal drink size over the 20th century. “It’s much easier now to reinforce a consensus than it was back then because you see so many drink recipes circulating,” he says.

To that point, the consistency of the 3-ounce formula was codified during the early aughts cocktail revival, when knowledge, information, and rediscovered classics were being shared and debated among the cocktail cognoscenti. The movement served as a rejection of the oversized glassware of the ’70s, ’80s, and ’90s.

“The cocktails of the late 20th century were simply too big,” Simonson says. “You can blame the ubiquitous Martini glass, which were like fish bowls. The return to 3-ounce cocktails at the turn of the century was nothing more than a long-in-coming correction. The huge cocktails of the ’80s and ’90s were an aberration.”

A new generation of bartenders in the early 2000s shook off the extended hangover left from the super-sized serves and looked to the past for inspiration. “The cocktail revival helped convince people to drink smaller drinks, but you can’t make them as small as they were before Prohibition,” says Wondrich, who thinks that 3 ounces is the ideal volume to convince someone of the value in their drink. It also keeps cocktails at the optimal temperature.

“There’s no chance of a 3-ounce cocktail getting too warm over the course of its short life,” Simonson adds. “If there’s a sidecar holding some of the liquid, so much the better.”

As something of a contrarian, William Elliott, executive bar director of Brooklyn’s Maison Premiere and co-author of “The Maison Premiere Almanac,” prefers 3 ¼ ounces as an ideal house spec.

“That’s the sweet spot for me as it leaves a little extra room for something fun or unexpected,” Elliott says. “There’s a very specific wash line thing going on with those classic Marie Antoinette-style Libbey coupes, which were so ubiquitous in the aughts. You can be a cocktail bartender all day long and have opinions but if you get a drink and it sits in front of you in a small coupe that’s a centimeter below the lip of the glass, that’s not a good look in my opinion.”

But even Elliott can’t deny the universal allure of 3. “Look, we can dissect it all we want and at any bar pop-up round I’ve done around the world in different markets and countries, no matter what specs I’m given they’re all very close to being 3 ounces. It seems to be an evolution of standardizing things at this point.”