A free simulator that shows a follower count as people and formations on the 3D streets of Seoul. No account needed; just enter a number.

With 1.2 m between the centres of people, the first to the last person is 1,198.8 m, about 1.2 km. That is (1,000 − 1) × 1.2 m, without body thickness.

Single file has 1 person per row, rows have 8, and a crowd up to 24. Rows = people ÷ people per row, rounded up. Length = (rows − 1) × 1.2 m; 0 people or a single row is 0 m. The crowd formation adds small random offsets, so its shown length is the baseline.

Input and distance go up to 50 million. Up to 12,000 nearby people are drawn individually; the rest become a band proportional to the crowd. From far away a guide line joins the start and end; its thickness is not the crowd’s width.

Roads and building outlines in central Seoul come from OpenStreetMap, with Mapzen terrain. The map covers about 4.05 × 4.89 km and 16,149 buildings. Some heights and facades are estimated or reconstructed, and people do not fully avoid buildings or each other. Long crowds beyond the map are an extension for comparing distance.

Apply a number, choose a formation, then pick Follow, Wide, Full view or Seoul map. The walk stops at the end of the route; restart it with the start-over button. In the Seoul map view you can drag and pinch to look around.

You need a browser with WebGL 2. Start with a smaller number or pause the walk. Hardware acceleration settings can limit 3D. If there’s an error, tap Try again. The distance examples and explanations below work without 3D.