A “cubit” in the Bible is an ancient length based on the distance from a person’s elbow to the tip of the middle finger, so it’s roughly the length of a human forearm. Most biblical and archaeological studies put a standard cubit at about 17–18 inches (around 43–46 cm), while a longer “royal” or “long” cubit used in some temple and construction contexts is closer to about 20–21 inches (around 50–52 cm).

What a cubit is

  • A cubit is an anthropic (body-based) unit: elbow to fingertip, used widely in the ancient Near East, including Israel and Egypt.
  • Because people’s arms differ, the exact length was never perfectly fixed, which is why modern estimates come as a range instead of a single exact number.

Typical size ranges

  • Standard/short cubit: commonly estimated at about 17–18 inches (roughly 44–45 cm).
  • Royal/long cubit: usually about 20–21 inches (roughly 50–52 cm), and associated with more official or sacred building projects.
  • Some modern Bible reference works split the difference and simply say “about 18 inches” for everyday reading convenience.

Why there’s debate

  • Archaeological evidence (inscriptions, measuring rods, ancient tombs) suggests both a shorter and a longer cubit were in use, which explains differences between sources.
  • Modern writers, pastors, and forum discussions sometimes argue for slightly larger figures (around 19–21 inches) when they try to estimate the size of things like Noah’s Ark more generously.

Examples in the Bible

  • Noah’s Ark is described as 300 cubits long, 50 cubits wide, 30 cubits high in Genesis 6:15; using an 18‑inch cubit makes that roughly 450 ft × 75 ft × 45 ft (about 137 m × 23 m × 14 m).
  • The Tabernacle and Solomon’s Temple are also measured in cubits, so whether one uses the short or long cubit changes reconstructed sizes in study Bibles and commentaries.

Quick takeaway

  • For everyday use, when you see “cubit” in the Bible, you can think “about 18 inches (1.5 feet)” and be in the right ballpark.
  • For more precise study, remember there were at least two main versions: a short cubit (~44–45 cm) and a long/royal cubit (~50–52 cm), and scholars choose between them depending on context.

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