The Grid rating program was developed to set the maximum premium that insurance companies can charge for basic coverage for any driving record. This page will allow you to calculate your grid premium and explain how the Grid rating program operates. As the Grid sets the maximum chargeable premium for basic coverage, most drivers (approximately 94.5%) do not pay these premiums. Insurance companies must compare a driver's premium under their current rating program to a driver's premium on the Grid and charge you the lesser of the two premiums.