For a classic Old Fashioned made with simple syrup, a good starting point is ¼ to ½ ounce (7–15 ml) of 1:1 simple syrup per 2 ounces (60 ml) of whiskey.

Quick Scoop

  • Most balanced recipes:
    • 2 oz bourbon or rye
    • ¼–½ oz simple syrup
    • 2–3 dashes Angostura bitters
    • Orange peel garnish
      This keeps the drink slightly sweet but still spirit‑forward.
  • Sweeter Old Fashioned:
    • Use closer to ½ oz simple syrup, especially with high‑rye or very spicy whiskey.
  • Drier / more boozy style:
    • Drop to about ¼ oz, or even just a barspoon of syrup if you like almost no sweetness.

How to Dial It In

  1. Start with ¼ oz simple syrup in your mixing glass. Stir with whiskey, bitters, and ice, then taste before straining.
  1. If it is too bitter or hot, add another ⅛–¼ oz syrup and stir again until it hits your preferred balance.
  1. Note the final amount so you can repeat your perfect house spec next time.

Simple Syrup Type Matters

  • Standard syrup (1:1 sugar to water) is common for Old Fashioneds and gives a clean, light sweetness.
  • Rich syrup (2:1) is sweeter and thicker, so many home and pro bartenders use only a barspoon per 2 oz of spirit rather than a full ¼ oz.

Many cocktail enthusiasts on forums report landing somewhere between a barspoon and ½ oz, depending on how sweet they like it and how bold the whiskey is.

TL;DR: Start with ¼ oz simple syrup per 2 oz whiskey, taste, then creep up toward ½ oz only if you want a noticeably sweeter Old Fashioned.

Information gathered from public forums or data available on the internet and portrayed here.