Measured: Shaft height is measured inside the boot from the top of the arch to the top edge of the shaft, heel excluded.
The basics
What to know about shaft height
Shaft height sets where a boot ends on your leg. That single line decides which hems it works with, how it flatters, and whether it fits at all. The measurement runs from the top of the arch inside the boot straight up to the top edge of the shaft, excluding the heel. Because the heel is excluded, the number stays the same across heel heights. A 15" shaft is 15 inches on a flat sole or on a 3" block.
The number matters more than the name, because the same shaft lands differently on different legs. On a 5'3" frame a 14" shaft can graze the knee; on a 5'10" frame it sits mid-calf. Hold a tape against your own leg and compare before trusting a label. Once a shaft reaches the calf muscle, check circumference alongside height.
The bands run contiguously from ankle to thigh. Each step up covers more leg, restricts more hemlines, and adds a fit problem. Ankle boots fit like shoes, and knee-highs must also clear the calf. Over-the-knee boots must stay up on a thigh that changes shape as you move.