Here's How Strong An Irish Coffee Actually Is
Given that it's spiked with booze, you might think an Irish coffee would offer a strong alcoholic kick, but you'd be mistaken. Less of a cocktail and more of a digestif or comfort drink on a chilly evening, Irish coffee is intended to warm the belly, not necessarily provide a buzz.
Irish coffee consists of four ingredients: sugar, coffee, whiskey, and heavy cream. Sans whiskey, you have yourself the makings of a sweet latte; what the whiskey brings to the table is additional flavor and a characteristic warmth. By sheer volume, however, the chief liquid in Irish coffee is coffee, so when having one, there's a higher risk of staying up past midnight than getting tipsy.
So, if you're using a standard recipe of 1 to 1-½ ounces of 80-proof (or 40% ABV) Irish whiskey for your coffee, the strength of the alcohol, which will be diluted by at least twice the amount of coffee, won't be that high — around 9%, which is a little more than a standard beer and certainly less than a glass of wine. So, while you're using a stiff spirit to make your Irish coffee, the finished drink won't be more potent than this unless you bump up the amount of whiskey used.
How to make Irish coffee at home
While it is great to go out and order an Irish coffee at a bar, they are very easy to make at home, provided you have the right ingredients. There is a fair amount of adaptability when it comes to the ingredients in an Irish coffee. There is the coffee, which should be brewed strong, but can be any blend or roast that you like. You can even swap out the traditional brown sugar for simple syrup or other preferred sweetener. The big thing, though, is the whiskey that you use. If you want to keep things as Irish as possible, you'll use something like Jameson, Bushmills, Tullamore D.E.W, Kilbeggan, or any number of excellent Irish whiskeys to flavor your drink. Whichever is your favorite, use that. Just don't use your favorite Scotch; otherwise, it'd be Scottish coffee, not Irish coffee.
To assemble the drink, take 2 teaspoons of sugar or a 1/2 ounce of simple syrup, and mix it with 3 ounces of hot coffee and 1-1/4 ounces of Irish whiskey in a warmed toddy glass. Then, with a deft hand, use an overturned spoon to gently pour 1 ounce of lightly whipped heavy cream over the top of the coffee so that it sits as its own separate layer. Don't stir your coffee, but drink it through the cream. And there you have yourself a warm, sweet, flavorful, slightly boozy Irish coffee.