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Kelley Blue Book Diminished Value Calculator: Why Your Car Isn’t Worth Full KBB Book Value After an Accident

Kelley Blue Book Diminished Value Calculator: Why Your Car Isn’t Worth Full KBB Book Value After an Accident

February 11, 2025
Graphic about learning how an accident impacts Kelley Blue Book value.

If you’re still using the full Kelley Blue Book values to determine the price of your vehicle after a car accident, you’re probably not factoring in the diminished value of your car.

Now that your car’s been in an accident you can’t estimate what you could sell it for by using the excellent or very good Kelley Blue Book values.

Those values won’t take into consideration your car’s diminished value – the fact that when potential buyers of your vehicle learn about your vehicle’s accident history, they’re going to offer you a lot less than what they would be willing to pay for a similar vehicle without an accident history.

Your Kelley Blue Book car value after an accident will be less than what it was before the accident occurred. You can estimate the diminished value of your vehicle using methods like the Kelley Blue Book diminished value calculator. Continue reading to learn more.

There’s No Such Thing as a Perfect Repair

A vehicle that has been repaired after an accident will never be the same as it was before it was hit, even if the repairs look outstanding.

While collision shops try to repair vehicles to industry standards, those standards are not always equal to factory-built standards.

When a vehicle is made in a factory, robots are used to laser weld panels together and entire vehicle structures are dipped into a bath of anti-corrosion coatings. That process can’t be replicated in a body shop where plug, mig, and tig welds are used to put a vehicle back together after an accident, and corrosion protection is manually applied and may not reach inner panels and cavities.

As a result, a repaired vehicle may never have the same structural integrity or be as resistant to rusting as a vehicle that has never been in an accident.

Repair shop welds generate a lot more heat than the laser welding process does at the factory. The excess heat weakens high-strength metals and changes their properties and performance. These welds won’t look as good as the factory welds and a trained eye can spot the difference.

All of the above are reasons why an accident and collision repair history permanently changes a vehicle’s condition. You can use the Kelley Blue Book diminished value calculator method to see how the change in your vehicle’s condition has impacted its value after an accident.

KBB Vehicle Condition Quiz

A vehicle that is well cared for without an accident history can be rated in “excellent” or “very good” condition according to KBB’s condition grading categories. Once this same vehicle has undergone collision damage repairs, the condition rating will drop to a lower category such as “good” or “fair”, and this will negatively affect the KBB car value.

You can use Kelley Blue Book’s vehicle condition quiz to categorize your car’s condition.

There are several questions on the condition quiz that pertain to bodywork, paintwork, as well as frame/unibody repair.

When selecting “significant amount of paint and/or bodywork” under the Paint or body work performed section, or when selecting “repaired, altered, replaced” under frame/unibody, Blue Book will downgrade the condition rating into the “good” category or into the category of “fair” when there have been frame/unibody repairs.

KBB vehicle condition quiz.

Kelley Blue Book Diminished Value Calculator

While this may not be the most accurate method of calculating diminished value, you can use the Kelley Blue Book condition rating grades and KBB book values to perform a rudimentary diminished value calculation.

To use Kelley Blue Book to calculate the diminished value, select the appropriate pre-accident condition rating category using the condition quiz. Then, take the quiz a second time and select “significant amount of paint and/or body work” and don’t forget to also select “repaired, altered, replaced” under the Frame/unibody section if your vehicle underwent any structural damage repairs.

Once you have the two KBB condition categories, the next step is to run the Kelley Blue Book values using both of those condition categories. Then, take the difference between the two values to determine the Kelley Blue Book diminished value.

2023 Honda Accord EX, KBB “excellent” $26,442

2023 Honda Accord EX, KBB “fair” $23,206

$26,442 - $23,206 = $3,236 diminished value using KBB as a calculator

We aren’t endorsing this method of calculating diminished value and you certainly don’t want to rely on this method as your only form of diminished value documentation. The best way to prove diminished value is by obtaining a certified diminished value appraisal from a professional who specializes in diminished value.

At DVCHECK, we use hard data and accident vehicles from the market. A market data-driven approach to determining diminished value will be far more accurate than using this KBB calculator method.

Potential Buyers of Your Car will Demand a Discount to Address your Car’s Accident History

Your car’s accident history raises concerns such as:

  1. Is the vehicle safe and will it perform as designed in a future accident?
  2. Will it need expensive repairs in the future?
  3. Does the vehicle have missing damage that was never repaired?
  4. Will they have difficulty selling it someday?

As a result, a vehicle with an accident history will be less desirable and will attract a smaller pool of potential buyers. This will drive down the Kelley Blue Book car value after an accident.

Your diminished value after an accident is simply the discount that a buyer would demand in order to encourage them to buy your vehicle instead of a similar vehicle without an accident history.

You’ve suffered a real loss and there is something you can do about it. If you need help with your diminished value claim, contact us at (850) 201-1950 for a free claim review.

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About the Author

Jim Marshall is the founder of DVCHECK, an auto appraisal firm specializing in diminished value and fair market value appraisals. He works with a diverse range of clients, including vehicle owners, rental car companies, law firms, trucking companies, and insurance carriers.With over 26 years of comprehensive industry experience, Mr. Marshall holds several industry-recognized credentials, including the AIC (Associate in Claims) from The Institutes, and a CPCU (Charter Property Casualty Underwriter) designation, rated as one of the most valuable and distinguished insurance credentials in the field. He is also an ASE Certified Auto Appraiser, licensed auto appraiser, and an experienced senior claims adjuster.