We at Uber are always trying to give you the best ride experience possible. With upfront fares, you know how much you need to pay before you take your ride. However, your final fare may sometimes differ from the upfront fare in certain circumstances.
 
What is an upfront fare?
An upfront fare is the estimated amount shown to you before you book your ride. Fares are calculated using the expected time and distance of the trip and local traffic, as well as how many riders and nearby drivers are using Uber at that moment. The fare is completely inclusive of toll charges.
More details on upfront fares:
Q: Do I get charged when I book my Uber ride? Why do I get a SMS from my bank?