What every home bar needs

Barello is a home cellar and bar app that tells you what to open tonight, what to keep, and what you can mix from what you have.

Every count on this page is taken from its cocktail library: 80 recipes, each carrying the rules that decide whether a bottle on your shelf satisfies an ingredient. That's the same engine the app runs on, so nothing here is an estimate.

The library and the matching tool are free and need no sign-up. The cellar side, with the drinking windows, is the app.

Half of a cocktail isn't a spirit. Limes block more drinks in this library than any bottle on the bar shelf does, and lemons and sugar are close behind.

So the first shopping list is lemons, limes, sugar or sugar syrup, soda water and mint. Everything below assumes you have them, exactly as the app does when it works out what you can make.

They also get you 12 drinks on their own. These are the non-alcoholic ones, built from juice, soda and citrus with nothing off the bar shelf in them.

Read that table again and you'll see the plan break. Up to 3 bottles the answer is spirits, each one bringing its own drinks. At 4 the best shelf drops whisky (any) and white rum and picks up Campari or red bitter, sparkling wine and sweet vermouth instead, which isn't the sort of thing a buying guide usually admits.

The reason is combination. A second spirit sits beside the first and makes its own drinks; a bitter, a vermouth and a bottle of sparkling wine all meet the gin and each other, so each one buys drinks that need two or three bottles at once. That's where a Negroni, an Americano, a Spritz and a French 75 come from, and none of them exists on a shelf of three spirits.

So there are two honest answers rather than one. Buying three bottles and stopping there, buy gin, whisky (any) and white rum. Expecting to end up with six, buy the six in the bottom row in that order instead: the middle of that list is a little thinner, and the shelf you finish with is better.

Gin turns up in 21 recipes here and finishes 10 of them by itself: Bee's Knees, Clover Club, Gimlet, Gin & Tonic, Gin Basil Smash, Gin Fizz, Gin Sour, Saturn, Southside and Tom Collins. Nothing else in the library carries a list like that, because so many classics are a spirit, a citrus and a sweetener, and gin is the spirit that sits happily in the sour, the highball and the fizz alike.

The catch worth knowing before you spend: a second bottle rarely combines with the first. Gin and white rum between them make 14 drinks and not one of them uses both. That's fine. It's just not what "these two go together" usually means. The two-bottle table has the honest numbers for every pair.