In this guide
Insurers calculate your car insurance rate by estimating how likely you are to file a claim and how much that claim might cost, then pricing the policy to match. They use a mix of factors about you, your car, where you drive, and the coverage you choose. The exact formula is different at every company, and your state limits which factors are allowed, so two drivers with the same profile can see very different prices.
Key takeaways
- Pricing is a prediction of risk. Insurers combine many factors, and each company weights them differently.
- Common factors include driving record, claims history, age, location, vehicle, annual mileage, and in many states a credit-based insurance score.
- Your coverage choices, such as limits, deductibles, and optional coverages, directly change the price.
- Some rules vary by state, including whether credit information may be used.
- Because formulas differ, comparing quotes from several insurers using the same coverage is the fairest way to see the range.
The basic idea: underwriting and rating
State regulators and the National Association of Insurance Commissioners (NAIC) describe pricing as two connected steps. Underwriting decides whether the insurer will cover you and in which risk group. Rating sets the premium for that group.
Insurers pool premiums from many drivers and use the pool to pay claims. To keep the pool fair, they try to charge each driver in line with expected claims. Actuaries study past claim data to find which characteristics tend to go along with more or costlier claims. Those characteristics become rating factors.
No single factor sets your price. A rating factor usually nudges the premium up or down, and the nudges are combined into a final number. That is why a change in one thing, such as moving to a new ZIP code, can matter more for one driver than another.
Factors about you
These personal factors are commonly used, though not every state allows every one:
- Driving record. Past violations and at-fault accidents suggest higher risk. The NAIC notes that your claim and violation history is a major input.
- Age and driving experience. Claim rates differ by age group, and new drivers often pay more because they have little track record.
- Gender and marital status. Some states permit these and some restrict them. The NAIC lists them among factors that can affect rates where allowed.
- Prior insurance history. A prior cancellation for nonpayment can affect your rate, according to the NAIC. Many insurers also look at whether you have had continuous coverage.
- Credit-based insurance score. This is not the same as a lending credit score. Insurers in states that allow it use it to predict the likelihood of loss. See the section below.
Insurers do not use race, religion, or income to price auto policies. Our guide to how your credit affects car insurance rates goes deeper on credit.
Factors about your car
The Insurance Information Institute (Triple-I) says premiums are based in part on the price of the car, repair costs, its safety record, and the likelihood of theft. In practice, insurers look at:
- Make, model, and year. Expensive-to-repair vehicles and models with higher theft or claim rates tend to cost more to insure. The NAIC notes luxury and sports cars average more claims.
- Safety and anti-theft features. Some features may earn discounts, depending on the insurer and state.
- How you use it. Commuting, business use, and annual mileage all matter. More time on the road means more exposure to accidents.
The NAIC also notes that usage-based programs can track details such as miles driven, time of day, hard braking, and fast acceleration. If you are curious, read our article on usage-based (telematics) car insurance.
Factors about where you live and park
Your garaging address is one of the most important inputs. The NAIC explains that urban areas tend to have more claims than rural areas, so territory is part of rating. Insurers may look at claim patterns in a ZIP code, such as accident frequency, vehicle theft, vandalism, weather damage, and repair costs.
That is why moving across town can change your premium even if nothing else does. It is also why you must report a move to your insurer. Using an old address to get a lower rate can lead to a claim problem or a canceled policy.
Factors you control: coverage choices
Coverage is the part of the price you decide. Insurers price each coverage separately and add them together.
| Choice | Effect on premium | Trade-off |
|---|---|---|
| Higher liability limits | Usually raises it | More protection if you cause a serious accident |
| Adding collision and comprehensive | Raises it | Pays for damage to your own car |
| Higher deductible | Usually lowers it | You pay more out of pocket after a claim |
| Optional extras (rental, roadside) | Raises it slightly each | Convenience after a loss |
| Bundling policies or insuring several cars | May lower it, depending on the insurer | Fewer companies to shop between |
Triple-I estimates that raising a collision and comprehensive deductible from $200 to $500 could reduce those costs by 15% to 30%, and going to $1,000 could reduce them by 40% or more. Results vary, and you should only choose a deductible you could afford to pay. See how car insurance deductibles work.
Credit-based insurance scores
Where allowed, insurers use credit-based insurance scores to help predict loss. The NAIC says they are used both for underwriting and for rating. It also says many states bar insurers from using the score as the only reason to raise rates or to deny, cancel, or not renew a policy.
The NAIC's page, last updated January 2024, lists California, Hawaii, Maryland, Massachusetts, Michigan, Nevada, Oregon, and Utah as states that ban the use of these scores in setting rates or in offering or renewing a policy. The page does not say whether each ban applies to auto insurance specifically, and laws change, so check your state insurance department for current rules.
Why companies give different quotes
Even with the same inputs, insurers can land on different prices. Each company has its own claims history, target customers, expenses, and formulas. One may weigh a recent accident heavily, while another focuses more on mileage or credit. Rates must also be filed with or approved by the state in many places, so the same insurer can price differently from one state to the next.
Good to know: The NAIC advises giving every company the same information when you shop: vehicle details and use, driver's license numbers, the number of household drivers, and the coverages and limits you want. That makes quotes comparable.
How to see what is driving your price
- Pull out your declarations page. It lists your coverages, limits, deductibles, and premium by coverage.
- Check that the vehicle, address, annual mileage, and drivers on the policy are accurate.
- Ask your insurer which discounts are applied and which you might qualify for. Our car insurance discounts checklist can help you ask the right questions.
- Compare quotes from several insurers using the same limits and deductibles.
If your premium jumped, our guide on why your car insurance may have gone up walks through the most common causes. For a broader overview, start with how car insurance works.
What you cannot change, and what you can
Some inputs, like your age, are fixed. Others change slowly, such as a clean record building over time. A few are within your control now: the car you buy, how many miles you drive, the coverages and deductibles you pick, and the accuracy of what you tell the insurer. Focusing on those is more productive than chasing a single "secret" factor.
A good habit is to review your coverage and shop around at renewal, because company formulas and your own situation both shift over time.
Frequently asked questions
What is the biggest factor in my car insurance rate?
It differs by insurer and state. The NAIC notes that claim history and driving record have a strong influence, while location, vehicle, coverage choices, and in many states credit-based insurance scores also play a role.
Do insurers use my race or income to set rates?
No. Triple-I notes that auto insurers do not use race, religion, or income when pricing a policy. Other factors, like location and credit-based insurance scores where allowed, are debated by consumer groups and regulators.
Why is my quote different from my friend's with the same car?
Rates depend on each person's driving record, age, address, coverage, deductibles, and the insurer's own formula. Small differences in any of those can change the price.
Does my credit really affect car insurance in every state?
No. Some states ban or restrict credit-based insurance scores. Check your state insurance department for what applies to you.
Can I find out why I was quoted a certain price?
Ask the insurer or agent which factors affected your quote. If credit information contributed to a higher rate or denial, federal and many state rules give you rights to notice and to review the information used. Your state insurance department can explain specifics.
Sources
- NAIC – Auto insurance consumer overview
- NAIC – Credit-based insurance scores
- Insurance Information Institute – Nine ways to lower your auto insurance costs
- NAIC – "Declarations" of Saving
General information only. This guide explains general concepts and is not insurance, legal or financial advice. Rules and prices vary by state and insurer. Check your policy documents and speak to a licensed insurance professional or your state insurance department about your situation.