Keep your waist under half your height. Enter two measurements to see your ratio, category, and healthy target.
Waist-to-height ratio (WHtR) divides your waist circumference by your height. The rule of thumb is simple and memorable: keep your waist to less than half your height. Research has found WHtR to be at least as good as — and often better than — BMI at flagging cardiometabolic risk, and it applies with one boundary across sexes and most ethnicities.
A ratio of 0.5 is the key line. Below it, most people fall in the healthy range; at 0.5 to 0.6 risk starts climbing, and 0.6 or above signals substantially elevated risk. Because the target scales with your height, a 5-foot adult and a 6-foot adult get an appropriately different waist goal from the same rule.
Tip: A single number is easy to track. If your waist creeps toward half your height, it's an early nudge to check your calorie balance and activity before BMI would flag anything.
Measure your bare waist at the midpoint between your lowest rib and the top of your hip bone, breathing out normally without sucking in. Use the same height figure you'd give at the doctor. Since both numbers share the same unit, inches and centimetres yield the identical ratio.