If you're asking someone's height, you can say "How tall are you (in inches/centimeters)?"

In the United States the customary way to state a height is in feet and inches. If someone asks me "how tall are you?" I answer "Five feet, eleven inches." On a form I would write 5' 11" . It is not customary to say "71 inches"--people would understand but they would need to think about it. If you need to know in centimeters, you would ask "how tall are you in centimeters?" or "How many centimeters tall are you?" But I am afraid that the metric system is unfamiliar in the United States, and people might not know the answer. By the way, Google will do conversions for you. If I "search" for 5' 11" in cm Google responds 180.34 cm

What is your question ? Did you mean: How many centimeters are their in one inch? 1 inch = 2,54 cm