How much does it take from Tiananmen to Summer Palace with subway?

You can walk to Qianmen Station to take the subway line 2 to Xizhimen Station, where you can transfer to line 4 to Beigongmen. Take the Exit C or D and walk about 0.6 miles, you will reach the summer palace.The subway fare is CNY5 and the duration is about 37 mins. By the way, it is around 19km between.