I like my Starbucks and usually order an Americano, which is made by adding hot water to shots of espresso. The ratios they use are 2 shots for a Tall (12 oz), 3 shots for a Grande (16 oz), and 4 shots for a Venti (20 oz).

If you do the math that is different strengths of coffee depending upon the size ordered. What simple rule do I use when ordering any size to ensure I always receive my coffee of a consistent strength?