Uninsured / Underinsured Motorist Calculator — United States

UM coverage pays your injury damages when an at-fault driver has no insurance or flees the scene. UIM coverage pays the shortfall when the at-fault driver's liability limits are too low to cover your damages. You claim against your own insurer, up to your UM/UIM policy limit.

States use one of two approaches. In offset states, your UIM limit is reduced by what the at-fault driver's insurer paid (a $100,000 UIM limit minus a $25,000 payout leaves $75,000). In add-on/excess states, UIM stacks on top of the liability payment up to the full UIM limit. This dramatically changes recovery.

Stacking lets you combine UM/UIM limits across multiple vehicles on your policy (or multiple policies). If you have three insured cars each with $50,000 UM, stacking can give you $150,000 in coverage. Some states permit stacking, others prohibit it or require you to reject it in writing.

Yes. Uninsured motorist coverage typically covers hit-and-run (phantom vehicle) accidents where the at-fault driver is unidentified. Most states require prompt reporting to police and, sometimes, independent corroboration of the phantom vehicle - notify your insurer immediately.

A UM/UIM claim is made against your own insurer because someone else was at fault. Most states prohibit insurers from surcharging you for a not-at-fault UM/UIM claim, though practices vary. Review your policy and state regulations with an attorney.