How Car Insurance Rates Are Calculated: The Rating Factors Explained

The basic idea: pricing expected claims

An auto insurance premium is an estimate of the claims you're likely to cause or suffer, plus the insurer's expenses. Insurers build rates from large amounts of claims data and file them with each state's insurance regulator. State law requires rates that are adequate, not excessive and not unfairly discriminatory.

In simple terms, most insurers take a base rate for each coverage in your area and multiply it by factors for your situation. A factor above 1.0 raises the price; below 1.0 lowers it. Every insurer builds its own formula, which is why quotes for the same driver can differ so much.

The main rating factors at a glance

Where the car is kept

NAIC explains that your premium depends on the insurer's claims experience in your ZIP code or territory, and that urban areas tend to cost more than suburban or rural ones. Denser traffic means more crashes, and cities often have more theft, vandalism and lawsuits. Weather such as hail and flooding raises comprehensive costs in some regions.

Always give the address where the car is actually parked overnight. Using a relative's cheaper address can void coverage. You can see how state averages compare in our state directory.

You as a driver: age, experience and record

• Driving record. NAIC notes that insurers typically ask for three years of driving history and check a motor vehicle report for every named driver. At-fault accidents, speeding tickets and DUIs raise prices; a clean record lowers them.
• Age and experience. Triple-I notes that drivers under 25, and especially teens, generally pay more because they have more crashes. Prices often ease through middle age and may rise again for older drivers in some states. See teen driver insurance.
• Gender and marital status. Where allowed, these can affect rates. Several states, including California, Hawaii, Massachusetts, Michigan, North Carolina and Pennsylvania, don't allow gender to be used in auto pricing.

Your vehicle

NAIC says rates are higher for cars that cost more to repair or replace and for sports cars, and lower for cars with features that improve passenger protection or deter theft. The Highway Loss Data Institute (HLDI), part of IIHS, publishes insurance loss results by make and model, and those differences show up in premiums. Advanced safety sensors can prevent crashes but also raise repair costs when damage does happen.

To compare how models stack up, use our vehicle insurance cost index.

Credit-based insurance scores and where they're restricted

A credit-based insurance score is different from a lending credit score. It uses parts of your credit report, such as payment history and outstanding debt, to predict insurance losses. NAIC notes that in most states, insurers can't use it as the sole reason to raise rates or to deny, cancel or refuse to renew a policy.

State rules differ widely:

• Not allowed for auto rates: California, Hawaii, Massachusetts and Michigan don't allow insurers to use credit information to set auto insurance rates.
• Limited: Maryland lets insurers use credit to rate a new auto policy but not to refuse, cancel or non-renew coverage or raise a renewal premium. Utah allows credit only to lower rates or together with other factors. Oregon bans canceling or non-renewing a policy based on credit.
• Life-event protections: Some states, such as Michigan and Nevada, require insurers to make reasonable exceptions for events like serious illness, a death in the family or identity theft.

State laws change, so check your Department of Insurance for the current rules where you live.

Myths: car color and other things that don't matter

• Car color. Triple-I says color doesn't factor into auto insurance costs. A red car costs the same to insure as the same car in white.
• "Older drivers always pay more." Not necessarily. Triple-I notes older drivers may qualify for discounts, such as for completing an accident prevention course.
• "Insurance covers anything that happens to my car." Only if you carry collision and comprehensive. A liability-only policy doesn't pay for your own car.
• "Quoting will hurt my credit." Insurance-related credit checks don't count against you the way loan applications can, so shopping around isn't something to fear.

Factors you can influence

1. Keep a clean driving record and avoid gaps in coverage.
2. Choose a vehicle with good safety ratings and moderate repair costs.
3. Pick deductibles you can afford and review coverages on older cars.
4. Ask about discounts and telematics programs; see our discount guide.
5. Where credit is used, pay bills on time and correct report errors.
6. Compare several insurers, since each weighs factors differently.

Our own estimates follow the same logic: they start from NAIC averages and apply modeled adjustments for common factors. The methodology page explains exactly how, and the premium estimator lets you try different scenarios.

Related guides

• How Much Is Car Insurance? Average Costs and What Drives Them
• Car Insurance Discounts: Common Types, Who Qualifies and What to Ask
• Teen Driver Car Insurance: Adding Your Teen, Choosing a Car and Cutting Costs
• How to Read a Car Insurance Quote and Compare Offers Apples to Apples
• Electric Vehicle Insurance: Why EVs Can Cost More and What the Data Shows