Car Insurance Coverage Comparison Calculator

Expected annual cost combines premium with expected out-of-pocket costs based on your risk assumptions:

• Expected annual cost = Premium + (P_coll × min(Collision Ded, Loss_coll)) + (P_comp × min(Comp Ded, Loss_comp))
• + (P_liab × max(0, Loss_liab − (Liability BI per accident + Liability PD)))
• + (P_med × max(0, Loss_med − PIP/MedPay Limit))

Coverage score compares each plan’s limits and deductibles to your targets:

• For limits: ratio = min(1, plan ÷ target)
• For deductibles: ratio = min(1, target ÷ plan)
• Weighted score = (Σ weight × ratio ÷ Σ weights) × 100

1. Enter your risk assumptions (probabilities and average losses).
2. Set target limits and preferred deductibles for scoring.
3. Adjust scoring weights to reflect what matters most.
4. Enable up to three plans and fill in their details.
5. Press Submit to view results above the form.
6. Download CSV or PDF to share your comparison.

Expected annual cost in the sample scenario

Using the default inputs, collision probability is 8% and the average collision loss is 4,500. If a plan’s collision deductible is 500, the modeled collision out‑of‑pocket per year is 0.08 × 500 = 40. Comprehensive is 5% with a 2,500 loss, so a 500 deductible adds 0.05 × 500 = 25. Premium plus these expected costs becomes a quick, comparable annual budget figure.

Coverage score from targets and weights

Each limit is scored as min(1, plan ÷ target). With targets set to 100k/300k liability and 50k property damage, a plan that matches those limits earns ratios of 1.00 for those parts. Deductibles are scored as min(1, target ÷ plan), so a 500 preferred deductible gives a perfect 1.00 when the plan deductible is 500 or lower. The weighted average is then scaled to a 0–100 score.

Deductible trade-offs measured in currency

At the same 8% collision probability, moving from a 1,000 deductible to a 250 deductible changes expected collision out‑of‑pocket from 0.08 × 1,000 = 80 to 0.08 × 250 = 20. That 60 difference is visible immediately, before considering premium. If your comprehensive probability is 5%, a 1,000 deductible adds 50 per year while a 250 deductible adds 12.5.

Liability and medical gaps can dominate outcomes

The calculator estimates liability out‑of‑pocket as max(0, loss − (BI per accident + property damage)). If liability loss is 450,000, and limits total 350,000, the gap is 100,000. With a 2% probability, the expected annual add‑on becomes 0.02 × 100,000 = 2,000, often larger than premium differences. Medical gaps work similarly when losses exceed PIP/MedPay.

Reading the value index and recommendation

Value index is (coverage score ÷ expected annual cost) × 1,000, so a 95 score and 1,185 expected cost yields about 80.2. The recommendation blends a cost score and coverage score using your chosen weights, such as 50/50. Adjust weights to test how price-sensitive your decision is. Re-run comparisons whenever premiums or driving conditions change.

Why is expected annual cost different from premium?

Premium is fixed, but expected annual cost adds modeled out-of-pocket costs from collision, comprehensive, liability gaps, and medical gaps using your probabilities. It helps compare plans on a single annual number.

What do the probability inputs represent?

They are your estimated chance of one claim type in a year. Enter percentages like 8 for collision. If unsure, start with conservative values and run sensitivity checks by increasing or decreasing each probability.

How do I choose target limits and deductibles?

Targets are your preferred protection level. Use limits you consider acceptable and deductibles you could comfortably pay at claim time. The coverage score shows how closely each plan matches those preferences.

Why do lower deductibles increase the score?

For deductibles, the ratio is min(1, target ÷ plan). A plan deductible lower than your preferred maximum meets the target, so it scores 1.00 for that category and raises the weighted score.

Can I compare extras like rental and roadside?

Yes. Rental is scored against your rental-per-day target. Roadside can be included or ignored using the roadside target switch. Extras also appear in the plan fields, so you can compare them consistently.

Does the recommendation guarantee the best policy?

No. The recommendation follows your weights and your assumptions. Real pricing depends on underwriting, exclusions, and local rules. Use the result as a structured shortlist, then confirm details with the insurer.

• Use the same assumptions for every plan to keep the comparison fair.
• If you have financing, consider whether gap coverage matters.
• Higher limits may protect assets but usually raise premiums.
• Lower deductibles reduce out-of-pocket but can cost more upfront.