A home bar usually starts with a shopping list copied from a guide: eight bottles, three liqueurs, a bag of gadgets. Most of it sits untouched. A better question is simpler: which one bottle, bought next, lets you make the most new drinks? That answer changes as your shelf grows, which is why a fixed list is the wrong tool.
The planner below holds 19 well-known drinks, two of them alcohol-free. Tap what you already own and it shows what you can make now, what is one ingredient away, and which purchase would open up the most drinks next.
For each drink it checks the ingredients against your shelf. If nothing is missing, the drink is ready. If exactly one thing is missing, it goes in the “one away” list. The “buy next” ranking then asks, for every item you do not own, how many drinks become ready if you add only that. Ties are broken by how many drinks the item appears in at all, so a bottle that is useful everywhere beats one that finishes a single recipe.
Try it from the empty shelf and a pattern shows up. Fresh lemons, fresh limes, sugar syrup and soda water are cheap, so they are the sensible foundation: nearly every sour and highball in the list leans on them. After that, one spirit at a time is the point. With just those four basics, gin is the first bottle to buy: it opens a Tom Collins and a Gimlet at once. Whiskey adds a Whiskey Sour, white rum a Daiquiri, and fresh mint turns the rum into a Mojito (and gives you an alcohol-free Virgin Mojito for free).
The cheapest bottle is not the best first buy. The best first buy is the one that shares ingredients with the most drinks you already want.
Drinks fall into three families, and each family shares a few ingredients. Sours (Daiquiri, Whiskey Sour, Margarita, Sidecar, Gimlet) are a spirit, citrus and something sweet. Stirred, spirit-forward drinks (Old Fashioned, Manhattan, Negroni, Dry Martini) are spirit plus a fortified wine or a bitter. Long drinks and highballs (Gin and Tonic, Moscow Mule, Cuba Libre, Mojito) are a spirit plus a fizzy mixer.
Because sours share citrus and syrup, every extra spirit you add gets a ready-made recipe. The stirred family is different: it needs bottles that do nothing alone. Sweet vermouth is the clearest case. It finishes a Manhattan, and together with Campari it opens the Negroni, the Americano and the Boulevardier, three drinks that share exactly the same two extra bottles. Once you own the whiskey, gin, rum, sweet vermouth, bitters and Campari from the planner, you are past half the list.
Notice that the planner also says something about bottles to leave for later. Cognac, tequila, vodka, Aperol and prosecco each unlock only one drink, and an orange liqueur needs cognac or tequila to do anything. They are fine to buy when you know you will drink the recipe they serve, not as insurance.
A few habits keep the shelf cheap:
Not every glass needs a spirit. Soda, ginger beer, lime, lemon, mint and sugar syrup already make the two alcohol-free drinks in the planner, and they are ready the moment you own them. A fizzy ginger and lemon drink or a Virgin Mojito is a perfectly good answer for a guest who is driving, pregnant or simply not drinking. Pour all drinks with measures rather than by eye, drink slowly, and never mix drinking with driving.
The planner is a map, not a rule: if you love bitter drinks, buy the Campari first and let the order bend to what you actually pour.