Simple syrup is exactly what it sounds like: sugar and water, dissolved in equal parts by volume. It is the most basic ingredient in the bar and one of the most important — the difference between a syrup and dry sugar is the difference between a clean, integrated drink and a glass that grits at the bottom.
Why Dissolved, Not Dry
Sugar will not fully dissolve in a cold, shaken cocktail. Drop a teaspoon of sugar into a Daiquiri's shaker and you will pour a cloudy drink with crystals at the bottom of the glass — the sweetness arrives late, in clumps, and the texture is gritty. Dissolved into water first, the sugar joins the drink as a uniform liquid; it integrates instantly, sweetens evenly, and pours clean.
This is why almost every sour cocktail — Daiquiri, Whiskey Sour, Sidecar, French 75 — calls for a syrup rather than a sugar measure. The drink's clarity depends on it.
The 1 : 1 Build
One part white sugar, one part water, by volume. The sugar dissolves cold if you stir long enough, but a brief warm on the stove takes thirty seconds and saves a lot of stirring. Do not boil — boiling reduces the water and changes the ratio.
Equal Parts by Volume
The "by volume" matters. One cup of sugar plus one cup of water yields roughly 1.5 cups of finished syrup. The dissolved sugar takes up space; do not expect the volume to double.
Simple vs Rich Syrup
If a recipe calls for rich simple syrup or 2 : 1 syrup, it wants twice as much sugar as water. The result is thicker and sweeter; tiki recipes use it, and a quarter-ounce of rich syrup roughly equals a half-ounce of simple. For demerara-based recipes that want a fuller, more molasses-leaning sweetness, see the dedicated Rich Demerara Syrup page.
Storage and Shelf Life
Stored cold, in a clean jar, simple syrup keeps about a month before it begins to develop a film or cloudiness — the early signs of fermentation. Some bartenders extend that to several months by adding a teaspoon of vodka or by making the syrup at a 2 : 1 ratio (the higher sugar concentration is self-preserving). For a home bar, a month is more than enough; make a small batch as needed.
Bottom Line
Keep a jar in the fridge. It costs nothing to make, lasts a month, and lifts every shaken sour you mix. The single most useful component in a home bar after the spirits themselves.