A cubit is an ancient unit of length based on the distance from a person’s elbow to the tip of the middle finger, and it was typically around 18 inches (about 45 cm).

Because it was based on the human body, the exact length varied by culture and time period.

  • A “short” or common cubit is often taken as about 18 inches (≈45 cm).
  • A “long” or royal cubit could be closer to 20–21 inches (≈50–53 cm).
  • Modern conversion tables sometimes use more precise values like 17.7 inches for an Egyptian cubit.

So when someone asks “how long is a cubit,” the practical, rounded answer is: about 18 inches / 45 cm , but in historical studies you will see a range from roughly 17.5 to 21 inches depending on which cubit is meant.

Information gathered from public forums or data available on the internet and portrayed here.