There are two factors that determine what you pay for auto insurance.
These are underwriting and rating.
Auto insurance company use underwriting to find out your personality and decide how much risk you present. You are then grouped with others with similar risks.
Based on the outcome of their underwriting process,insurers therefore use a rating system to set a price. This price is based on the insurer’s estimate of the risk to take responsibility financially for that person’s potential claim losses.

When you want to buy auto insurance, some enquiries will be made. These enquiries are to determine the amount of premium you will be reqiured to pay.

Some determinants of rates:

-coverage limits- (i.e., 25/50/25 vs 50/100/50 liability coverage). The more the auto insurance coverage limits, the more it will cost.
-age,gender,and marital status- (i.e., a 50 years old married female vs a 19 year old college student). Statistics have shown in auto insurance that a certain group of drivers have the tendencies to have more accidents.
-driving record- a driver with a record of at-fault accidents, tickets payment and moving violations often pay a higher premium than a driver with a good record.
-location- in auto insurance,rural drivers pay a less premium compared to city drivers. It is believed that cities have more traffic, thefts, etc.
-type of vehicle- in auto insurance, certain vehicles are more expensive to insure because they are damaged easily, more expensive to repair, and have more tendencies to be stolen
-family members- the driving history and ages of your family can affect your premium. Teenage drivers in your family may increase your premium.
-credit history- many auto insurance companies may use your credit history to determine your rates too.

However, different auto insurance companies use different underwriting and rating system, therefore, rates of the same coverage differs within auto insurance in New Hampshire.