How to calculate diminished value
To calculate diminished value, compare what your car was worth just before the accident with what it is worth after a proper repair. Buyers pay less for a car with a reported accident, so the gap remains even when the repair is perfect. The three methods in the calculator approach that gap from different evidence:
- Market difference. Ask two or three dealers for a written trade-in offer on the repaired car, or get an independent appraisal, and subtract it from the value before the accident.
- Comparable listings. Find similar cars for sale (same model, year, trim and mileage band, in your area) and split them by whether a vehicle history report shows an accident. The difference between the two averages is the market's own discount.
- The 17c formula. Many insurers start from the formula that came out of Georgia's diminished value litigation: a base percentage of the pre-loss value, multiplied by a damage modifier and a mileage modifier.
| Method | Inputs | Estimate |
|---|---|---|
| Market difference | $32,000 − $27,500 written offer | $4,500 |
| Comparable listings | clean average $32,200 − accident average $28,200 | $4,000 |
| 17c, as an insurer applied it | $32,000 × 10% × 50% × 80% | $1,280 |
The 17c formula and why it is usually lowest
The 17c formula multiplies the pre-loss value by a cap (commonly a small percentage), then by a damage modifier and a mileage modifier, so the result can only be a fraction of the cap. No official source publishes the modifier tables. Georgia's Insurance Commissioner never endorsed a formula, and a 2008 directive warned that total reliance on one formula or method may not be appropriate; the Court of Appeals of Georgia described the damage modifier as a subjective decision made by the adjuster.[1] That is why the calculator takes the three percentages from your insurer's own letter instead of filling them in.
Use the method with the best evidenceA written dealer offer or an appraisal for your exact car is stronger evidence than averages. Keep every listing you use, with the date and link, so you can show your work.
Who pays diminished value
A diminished value claim usually goes to the at-fault driver's liability insurer, not your own. Texas's Department of Insurance notes an insurer may owe a third-party claimant for loss of market value even after a complete repair,[2] Maryland calls it a valid component of a liability claim against the at-fault party,[3] and Washington says you typically file against the at-fault party's insurer.[4] Michigan's no-fault law limits what you can recover from the other driver to $3,000 of damage not covered by insurance.[5] The state-by-state rules we could confirm are on the diminished value claim guide.
If you are ready to send a claim, the self-help kit fills in a demand letter and a document checklist from these numbers:
Common mistakes
- Using the repair cost as the loss. Repair cost and diminished value are separate; a large repair does not by itself set the value lost.
- Comparing the wrong cars. Listings that differ in trim, mileage or region move the averages more than the accident does.
- Accepting a 17c figure without the inputs. Ask the insurer for the base, damage and mileage modifiers it used.
Normal age-and-mileage depreciation is a separate cost; the car depreciation calculator covers it, and the car insurance calculator estimates what coverage costs.
Frequently asked questions
How do you calculate diminished value on a car?
Subtract the repaired car's market value (from written offers, an appraisal or comparable listings with an accident history) from its value before the accident.
What is the 17c formula?
A formula many insurers use: pre-loss value × a base percentage × a damage modifier × a mileage modifier. Its modifier tables are not published by any official source and it usually gives a low figure.
Is this diminished value calculator an appraisal?
No. It does the math on the numbers you enter. Only an appraisal or real offers show what your car is worth.