Public Metered taxi fares can vary depending on the traffic conditions and the route taken. If you take the Expressway, you will need to pay the toll fee which is about 40 Baht extra.
To Khaosan Road - Thai Baht 300
Sukhumvit Road - Thai Baht 300
Ratchadaphisek Road - Thai Baht 300
All taxis will charge a 50 Baht Airport surcharge on top of the total amount on the meter.
To Pattaya, all the taxis charge a Flat Fee of THB 1300