Free Diminished Value Calculator
After an accident, your car is worth less — even after a perfect repair. Estimate how much value you lost, and what your insurer may owe you, in 15 seconds.
Your car is worth less now — even if the repair looks perfect
Here's the part the body shop won't tell you: once your car has been in an accident, it's worth less on the resale market forever — even after a flawless repair. The paint matches, the panels line up, everything drives fine. But the moment that collision shows up on a CARFAX or AutoCheck report, buyers pay less and dealers offer less. CARFAX's own research confirms it: a reported accident measurably drags down what a used car sells for (CARFAX).
That gap between what your car was worth before the crash and what it's worth after is called diminished value. It's a real financial loss. And if someone else caused the wreck, it's money you may be legally owed — money most drivers never claim because nobody tells them it exists. Insurers are not in a hurry to bring it up.
How the 17c formula estimates your loss
The calculator above uses the 17c formula — the diminished-value math that came out of the Georgia Supreme Court case Mabry v. State Farm (2001), and the same baseline method insurance adjusters reach for today:
- Start with a 10% cap. Take your car's pre-accident market value × 10% — the ceiling under this formula. A $30,000 car has a $3,000 cap.
- Apply a damage-severity factor (0.00–1.00). Severe structural damage keeps most of that cap; minor cosmetic damage cuts it down. Major damage (factor 0.75) → $2,250.
- Apply a mileage factor. Under 20,000 miles counts full; it steps down 0.8 / 0.6 / 0.4 / 0.2 as miles climb, hitting 0.0 at 100,000+. At 35,000 miles (0.80) → $1,800.
An honest caveat — and why the number still matters
The 17c formula is conservative by design. It was essentially an insurer's methodology, and many independent appraisers argue it understates real-world losses, especially on newer or in-demand vehicles. Treat this figure as your negotiating floor, not your ceiling.
Frequently asked questions
What is diminished value?
Diminished value is the difference between what your car was worth before an accident and what it's worth after repairs. Even a flawless repair can't remove the accident from the vehicle-history report, and buyers pay less for a car with a reported collision — that permanent loss is your diminished value.
How much diminished value can I claim?
It depends on your car's value, damage severity, and mileage. The 17c formula caps the estimate at 10% of pre-accident value, then reduces it for damage and miles. A $30,000 car with major damage and low mileage might land near $1,800 — but an independent appraisal often comes in higher.
Does insurance have to pay diminished value?
If another driver was at fault, their insurer generally owes you diminished value as part of making you whole (a third-party claim), and most states recognize this. Whether your own insurer must pay (a first-party claim) depends on your state and policy — Georgia requires it after Mabry v. State Farm, but many states let insurers exclude it.
Can I file a diminished value claim on my own insurance?
Sometimes. First-party diminished value depends on your state and your policy's language; many policies exclude it. Georgia is a notable exception where insurers must pay it. Check your policy's property-damage terms and your state Department of Insurance before assuming your own carrier will cover it.
How long do I have to file a diminished value claim?
A diminished value claim usually falls under your state's statute of limitations for property damage, often two to six years depending on the state (Georgia allows four). Don't wait — evidence and market comparisons are easier to document soon after the accident. Confirm your state's deadline before filing.
Do I need a professional appraisal?
Not for small claims, but it helps for larger ones. A licensed diminished-value appraisal (typically a few hundred dollars) carries far more weight with adjusters than your own estimate and often pays for itself. Pair it with market comparisons of similar cars with and without accident history.
Why did the insurance company offer me so little (or nothing)?
Lowballing diminished value is routine. Adjusters may deny it exists, run the 17c formula with understated inputs, or demand you prove the loss. Treat the first offer as an opening bid. Counter with your 17c number, an independent appraisal, and comparable listings — and escalate to your state Department of Insurance if needed.
What is the 17c diminished value formula?
The 17c formula is the diminished-value method that emerged from the Georgia case Mabry v. State Farm (2001). It caps the loss at 10% of the car's pre-accident value, then multiplies by a damage-severity factor (0.00–1.00) and a mileage factor (1.0 under 20,000 miles, down to 0.0 at 100,000+). It's a conservative baseline, not a ceiling.
What to do next
Disclaimer: This calculator provides an educational estimate using the industry-standard 17c formula. It is not an appraisal, an offer, or legal advice. Actual diminished value depends on your vehicle, local market, and state law. For a binding figure, consult a licensed appraiser or attorney.