How long neil armstrong on moon?

Confusion about the length of Armstrong's stay comes from measuring different things. The moonwalk itself, from opening the hatch of the lunar module Eagle to closing it again, lasted about 2 hours 31 minutes. The stay on the Moon, counted from touchdown to lift-off, was roughly 21 hours 36 minutes, most of it spent inside the cabin. Both figures are small against the mission as a whole, which ran a little over eight days from Florida to the Pacific.

Eagle landed in the Sea of Tranquillity late on 20 July, Universal Time, with less propellant margin than anyone had wanted. The flight plan called for a rest period first; the crew asked to skip it and depressurised early. Armstrong climbed down the ladder and stepped onto the surface in the small hours of 21 July UTC, about six and a half hours after touchdown, and Buzz Aldrin joined him some twenty minutes later. The hatch closed before the crew tried to sleep, and Eagle lifted off later that day to rendezvous with Michael Collins aboard Columbia.

Very little, by the standards of later missions. The two men planted the flag, took a call from the White House, photographed the site and the spacecraft, collected rock and soil, and set out a small experiment package with a passive seismometer and a laser reflector that is still used today. Neither strayed more than a short walk from the module, and both worked inside a tight schedule read up from Houston. Everything after Apollo 11 was longer: Apollo 12 managed two excursions, and by Apollo 17 the crew spent about three days on the surface and drove a rover kilometres from the landing point.