Depending on the exact location of the Old Quarter and the route, the distance from the Old Quarter of Hanoi to Noi Bai International Airport is between 26-30 km. One can reach the airport in 45 minutes, but depending on traffic ahead, it may take 1.5 hours to cover the distance. It's better to leave a buffer, just in case.
The commute from the Old Quarter of Hanoi to Noi Bai International Airport usually takes about 30-50 minutes, depending on traffic congestion and mode of transport used. Delays may be expected during peak afternoon hours due to even heavier traffic. A taxi or a private transfer will take a shorter time than public transport.
Take the metro to Dong Anh Street (Hanoi Station). After a few stops, the metro station will be near the intersection of Le Loi Street and Wat Phra Kaew (a Buddhist temple). From there, you will need to transfer to Line 2 (the Green Line), which runs along Hanoi's Central Axis. Follow the signs to the Airport Rapid Transit Station, which is located along Tran Hung Dao Street (Hanoi's main road), about 15 minutes from the airport.
Take bus number 67 (number 67) from the central hub at Hoan Kiem Square to the Airport Rapid Transit Station. This bus stops at several locations along the way, including Nguyen Tien Ba Bridge, Han Son Road, and East-West Road, and you can find the exact stops on the bus map.
Air taxi services normally require a booking of between VND 300,000 (USD 14) and VND 500,000 (USD 21) per person for the flight between the central business district of Hanoi and the airport, along with extra charges for luggage and other services.