Calculator Inputs
Example Data Table
| Scenario | PV recoverable | At-fault paid | Effective UIM limit | Setoffs | Deductible | Estimated UIM |
|---|---|---|---|---|---|---|
| Minor injury, fixed deductible | $18,500 | $10,000 | $25,000 | $0 | $500 | $8,000 |
| Higher damages, percent deductible | $72,000 | $25,000 | $50,000 | $2,500 | 5% | $21,250 |
| Stacking two vehicles, waived deductible | $40,000 | $15,000 | $60,000 | $0 | $0 | $25,000 |
Examples are illustrative only; real claims depend on policy terms and facts.
Formula Used
This tool is an estimate for planning and comparison, not legal advice.
How to Use This Calculator
- Enter all damages, including future items if needed.
- Choose a pain method, or leave it disabled.
- Add fault percent, at-fault limits, and payments received.
- Enter UIM limits, claimants, and stacking details.
- Add setoffs, deductible rules, and optional timing inputs.
- Click Calculate to see results, graph, and exports.
Article
Understanding underinsured gaps in real claim math
Underinsured motorist coverage becomes relevant when the at-fault payment cannot satisfy your recoverable damages. This calculator separates total damages, fault reductions, and carrier payments so you can see the remaining gap that UIM may address. It also highlights where policy limits, offsets, and deductibles constrain the final payout.
Building a damages picture that insurers can defend
Accurate inputs improve decision-making. Economic damages typically include medical costs, future treatment, lost wages, future earnings, household services, property losses, and incidentals like rental and towing. Optional pain and suffering is modeled as either a fixed amount or a multiplier on injury-related economic items. The result is a structured estimate you can review line by line.
How limits, stacking, and per-accident caps change availability
UIM availability depends on the method used. Difference-in-limits compares your UIM limit to the at-fault liability limit, while excess uses the UIM limit as an additional layer. If stacking is enabled, the per-person limit can increase by the number of covered vehicles, subject to any per-accident cap. The claimants field helps approximate how a shared accident limit can affect one claimant’s share.
Offsets, setoffs, and deductibles that reduce benefits
Many policies allow reductions for other benefits. This calculator supports a percent policy offset plus setoffs for PIP or MedPay, workers’ compensation, and other credits. After offsets, a deductible can be applied as a fixed amount, a percentage, or waived, with optional minimum and maximum caps. These steps show why a large headline limit may still produce a smaller net payment.
Net proceeds, timing assumptions, and exporting a clean record
After the estimated UIM payout, you can add an interest estimate over months to payment, then subtract attorney fees and liens to get a net-to-claimant planning figure. Exports provide a repeatable record for scenario comparisons, budgeting, and internal review. Treat outputs as estimates and verify final rules with policy language and counsel. Run multiple scenarios to understand how assumptions move your bottom line.
FAQs
1) What does “difference-in-limits” mean here?
It estimates UIM availability as your effective UIM limit minus the at-fault liability limit, then compares that amount to your remaining damages. If the at-fault limit is higher, available UIM can drop to zero.
2) When should I use the “excess” method?
Use it when your policy or jurisdiction treats UIM as additional coverage above the at-fault payment, not reduced by the at-fault liability limit. It still cannot exceed your remaining recoverable damages and any offsets.
3) How does stacking affect the estimate?
If stacking is enabled, the tool multiplies the per-person UIM limit by the number of stacked vehicles, then applies any per-accident cap and claimant sharing logic. This can increase the effective limit used for the calculation.
4) Why are PIP, MedPay, or workers’ comp included?
Some policies reduce UIM benefits by amounts paid from other coverages or reimbursements. Enter known setoffs so the estimate reflects potential credits the insurer may apply before the deductible and final payout.
5) What is the discount rate used for?
The discount rate converts future medical and wage amounts into a present value based on months to payment. This helps you model how future damages may be valued today. Set it to zero if you do not want present value.
6) Is the attorney fee calculation exact?
No. It applies a simple percentage to the estimated UIM proceeds (including optional interest). Real fee agreements, costs, lien negotiations, and settlement structures vary. Use it for planning and scenario comparisons only.