Overproof rum is rum bottled well above the usual 40% — anywhere from 57% to 75% ABV — and it is not a novelty. It is the ingredient that gives tiki drinks their backbone, the Zombie its reputation, and the Jamaican rum punch its soul. Used in small, deliberate amounts it makes drinks better. Used carelessly it ends evenings.

What is overproof rum?

The word comes from the old British proof system, under which 100 proof meant 57.15% alcohol by volume — the strength at which gunpowder soaked in spirit would still ignite, which is how sailors checked their ration had not been watered. Anything above that was over proof. The American system is simpler: proof is double the ABV, so a "151" is 75.5%.

In practice the category covers three things that are quite different from one another:

• Navy strength rums at around 54 to 57%, which are simply full-flavoured rums bottled a little strong.
• Jamaican white overproof at 63%, unaged, pungent and the everyday rum of Jamaica.
• 151s at 75.5%, usually from Demerara (Guyana) or Puerto Rico, used as floats, in flaming drinks and in tiki recipes that specify them.

How it's made

Nothing exotic: the same molasses fermentation and distillation as any rum, bottled with less water added. What changes the character is where it comes from. Jamaican overproof is pot- or column-distilled from long-fermented wash heavy in esters, and bottled unaged, so the full fruity funk — "hogo" — is intact. Demerara 151 comes off the wooden and metal stills of Guyana and is lightly aged, giving it burnt sugar and smoke. Navy-strength blends are usually aged pot-and-column rums married at the higher proof.

Some 151s have been discontinued or reformulated over the years — the most famous Puerto Rican one was withdrawn in 2016 — so recipes that name a brand may need a modern equivalent.

What it tastes like

Concentrated. Jamaican white overproof is overripe banana, pineapple, nail varnish and brine, with a heat that catches at the back of the throat; a drop in a drink reads as ripe tropical fruit. Demerara 151 is dark sugar, coffee, smoke and leather. Navy-strength Jamaican blends are rich, molasses-sweet, oaky and intense. All of them are too strong to assess neat without water; add an equal part and taste again.

Styles worth knowing

Style	Strength	In a drink
Jamaican white overproof	63%	Nuclear Daiquiri, rum punch, a dash in any daiquiri
Demerara 151	75.5%	The Zombie float, Jet Pilot, flaming garnishes
Navy-strength Jamaican blend	57%	Mai Tai split base, Old Fashioned, stirred drinks
Overproof blended "tiki" rums	66–69%	Designed to replace discontinued 151s
Cask-strength aged rum	55–65%	Sipping with water; a luxury Old Fashioned

Which bottle to buy

Start with a Jamaican white overproof and a navy-strength aged Jamaican blend. Between them they cover almost every recipe on this site that calls for overproof, and both are inexpensive for what they are. Add a Demerara 151 only if you make a lot of tiki drinks or want to flame things.

Read the ABV, not the marketing. "Strong" and "bold" on a label mean nothing; 57% or above does.

Using it in drinks

Three jobs. As a float: the Zombie finishes with a measure of 151 on top, and the Jet Pilot builds it into the recipe. As a split base: the classic Mai Tai and its cousin the Bitter Mai Tai use a navy-strength Jamaican rum for half the spirit, which is what gives the drink its depth. As a seasoning: a quarter-ounce of white overproof in a Daiquiri or Piña Colada adds fruit and funk without the drink tasting strong — the Nuclear Daiquiri takes that idea all the way.

Scale recipes by alcohol, not volume: an ounce of 151 is nearly two ounces of 40% rum in effect. And when a recipe flames a 151, keep it well away from the ice, the glass and your face, and never pour from the bottle near a lit drink.

Substitutes

For a navy-strength rum, use a full-flavoured 40% Jamaican rum and slightly more of it. For a 151 float, a navy-strength rum gives most of the effect; a cask-strength aged rum gives it with more polish. For white overproof in a daiquiri, a funky unaged Jamaican rum at 40% gets you partway. Do not substitute overproof grain spirit — it brings the strength and none of the flavour.

Storage

Upright, tightly closed, away from heat and open flame — at 75% the fumes are flammable. High-proof spirit is the most stable thing on the shelf and an opened bottle keeps for years. Do not store 151 near the stove.

Questions

What proof is overproof? Above 57.15% ABV by the old British definition, which is 114 US proof. Most people apply the word to anything over 50%.

Is overproof rum just stronger rum? The navy-strength bottles are. Jamaican white overproof and the 151s are distinct styles with their own flavour, which is why recipes specify them.

Can I drink it neat? You can, with water. Jamaicans drink white overproof with coconut water or ginger beer; nobody drinks 151 neat on purpose twice.

Why does my Mai Tai taste flat? Usually because it was made with a single light rum. The recipe wants an aged Jamaican rum at or near navy strength for half the base.