Taxis are available from outside each terminal's Arrivals level. Follow the signs.
Journey time to central Singapore is around 20-30 minutes.
Fare is approximately SGD$20-$30 with an additional airport surcharge of SGD$3-$5 depending on the time of day.
Limousine Taxis are also available at a higher price. They can be booked at the Limousine Taxi Service desks in the Arrivals Hall of each terminal.
Fare: fixed rate SGD$45.