A regular flat white coffee contains two espresso shots, which gives it a grand total of about 130 milligrams of caffeine.
Every flat white coffee has the same main ingredients: espresso, steamed milk, and foam.
Most commonly, the drink starts with two shots of espresso.
Standard recipes will usually yield a drink with 130 milligrams of caffeine, which is nothing to scoff at.
Because flat white coffees are made in smaller servings, they often have a bit more caffeine than a latte and taste a little stronger.
With ristretto instead of espresso, the caffeine content might be a tiny bit less, depending on the preparation method.
Flat white coffees made with ristretto end up with a stronger taste, but with a bit less caffeine.
In such cases, the latte would be weaker in taste and caffeine content than a flat white coffee.