The approximate total length of the Great Wall is 21,196 km.
That figure comes from a comprehensive Chinese mapping survey reported in 2012. It measures the surviving Great Wall system—including wall sections, trenches, and natural defensive barriers—rather than one uninterrupted stone or brick wall. The precise survey total is about 21,196.18 km, so 21,196 km is an appropriate rounded quiz answer.
The number is often misunderstood because the Great Wall is a network built over many centuries, not a single structure erected by one emperor. It includes fortifications from different dynasties and historical periods, spread across northern China. The best-preserved and most visited stretches are generally associated with the Ming dynasty, whose wall alone is measured at roughly 8,850 km when associated trenches and natural barriers are included.
Other popular figures can refer to narrower measurements, such as only standing wall sections or only the Ming wall. That is why estimates such as 5,000 km or 10,000 km may appear elsewhere, but they do not represent the mapped total of the full defensive system.