What Is the Rule of Thumb, Where Did the Expression Come From, and What Does it Mean?

In 1976, NOW incorrectly linked the expression “rule of thumb” with a 1782 public statement by an English judge.

On his opinion, a man should have the right to beat his wife as long as the stick used was no thicker than his thumb.

In fact, the real “rule of thumb” is a reference to building or baking something through the knowledge of experience rather than precise science, with the thumb being an instrument for a rough and improvised measurement.