Diminished Value Calculator (17c Formula)
Calculate a diminished value claim using the 17c formula most insurers apply. See the number they will offer, why it is conservative, and when an independent appraisal beats it.
Calculate a 17c diminished value claim
How this is calculated
This is the 17c formula, which came out of a Georgia class action and which a great many insurers now apply to third-party diminished value claims:
17c value = (pre-accident value × 10%) × damage modifier × mileage modifier
| Damage | Modifier | Odometer | Modifier |
|---|---|---|---|
| Severe / structural | 1.00 | 0 – 19,999 | 1.00 |
| Major | 0.75 | 20,000 – 39,999 | 0.80 |
| Moderate | 0.50 | 40,000 – 59,999 | 0.60 |
| Minor | 0.25 | 60,000 – 79,999 | 0.40 |
| None | 0.00 | 80,000 – 99,999 | 0.20 |
| 100,000+ | 0.00 |
Be clear about what 17c is. It is the insurer's method, and it is conservative by design. The 10% cap is arbitrary, and the mileage table zeroes out any car past 100,000 miles — which is plainly wrong, because a six-figure-mileage car with frame damage on its record still sells for less than one without.
So use this number for what it is worth: it tells you what the adjuster will offer. If your own research on comparable clean-history versus accident-history listings shows a bigger gap, an independent appraisal is what closes it. Several states also do not permit first-party diminished value claims at all, so check whether you are claiming against your own insurer or the at-fault driver's.
Frequently Asked Questions
What is diminished value?
The resale value your car permanently loses because it now has an accident on its history report, even after a flawless repair. Two identical cars, one with a reported collision, do not fetch the same price.
Is the 17c formula fair?
It is standard, not fair. It caps the claim at 10% of pre-accident value and reduces it to zero above 100,000 miles, neither of which reflects how the used market actually prices accident history. Treat it as the opening offer rather than the answer.
Can I claim diminished value from my own insurer?
Usually not. Most diminished value claims are third-party, made against the at-fault driver's insurer. A number of states do not recognise first-party diminished value claims at all, so establish which situation you are in before you file.
How do I beat the 17c number?
With evidence. An independent appraiser produces a report comparing your vehicle against clean-history and accident-history comparables. That report, not the formula, is what supports a higher figure in negotiation or small claims court.