What is the difference between the number score and the star rating?

Number Score

Your overall score, out of 100, is presented on the Dashboard screen in the app. This is the key measurement of your driving performance, calculated with data from your trips over the past two weeks. The app compares your performance to the typical driver population for each subscore, like hard braking or speeding, and then weighs your subscores together to produce an overall score. The app uses aggregated data from millions of users and billions of recorded miles to calculate your relative level of risk per mile.

Star Rating

The star ratings are granted for each individual trip and can be viewed on the Trips screen. They provide an idea of what happened on each trip. For a given trip, you can lose stars for any risky events that occur, such as phone use, hard braking, speeding, hard acceleration, and hard cornering.