Transferring between Tokyo’s two major airports, Narita (NRT) and Haneda (HND), is a significant journey that requires a minimum of 3 to 4 hours to be safe. The distance between them is about 80 kilometers (50 miles). The most convenient method is the Airport Limousine Bus, which takes approximately 65 to 85 minutes depending on traffic. Alternatively, the "Access Express" train (a joint service by Keisei and Keikyu lines) offers a direct rail connection that takes about 90 minutes. If you have a JR Pass, you can take the Narita Express to Shinagawa and then switch to the Keikyu line, which takes about 95 minutes. When you factor in clearing customs/immigration, collecting luggage, the actual transit time, and re-checking for your next flight, any layover shorter than 5 hours is considered "tight" and high-risk. Taxis are available but extremely expensive, often costing over ¥30,000 ($200+ USD).