In ancient times, before the advent of standardized measuring systems like the metric or imperial units, people primarily relied on readily available and relatable objects for measuring lengths. These often included parts of the human body or natural phenomena, leading to a diverse array of measurement units across different cultures and regions.

Here are some common methods and units used:

• Body Parts:
  • Digit or Finger: The width of a finger was one of the smallest units, often serving as a foundational measure.
  • Palm or Handbreadth: Equivalent to the width of a hand across the knuckles, typically four digits. In some cultures, a "hand" is still used to measure the height of horses.
  • Foot: The length of a human foot. This varied significantly depending on the individual and culture, but was a widespread unit.
  • Cubit: One of the most important ancient units, representing the length from the elbow to the tip of the middle finger. Cubits varied greatly; for instance, the Egyptian royal cubit was approximately 52.3 cm (20.6 inches), while others were shorter.
  • Pace or Step: The length of a single step. A "double pace" or "stride" was also used, representing two steps (when the same foot touched the ground again).
  • Fathom: The length of a man's outstretched arms from fingertip to fingertip, primarily used for measuring depths of water or ropes.
• Other Practical Units:
  • Link or Chain: In some agricultural contexts, chains of a certain length were used to measure land.
  • Stade or Stadium: Originally the length of a Greek athletic track, about 185 to 192 meters (607 to 630 feet). It was used for longer distances.
  • Mile: The Roman mile, or mille passus, meaning "a thousand paces," was approximately 1,478 meters (4,850 feet) or 1.478 km.
  • Day's Journey: For very long distances, the distance a person or group could travel in a day was used, though this was highly variable based on terrain, load, and mode of travel.

The inherent problem with body-part measurements was their inconsistency from person to person. To address this, some ancient civilizations developed rudimentary standardization. For example, the Egyptians had a "royal cubit" standard that was maintained and reproduced, often carved into stone or made of wood, to ensure consistency in large construction projects like the pyramids. Similarly, the Romans had standards for their foot and mile. Despite these efforts, local variations persisted for a long time, making trade and large-scale projects challenging without clear agreements on the units being used.