How to Calculate Diminished Value After an Auto Insurance Claim
TLDR: How to Calculate Diminished Value on Auto Insurance Claims
Diminished value is the loss in resale value after your car is repaired from an accident.
Use the 17c formula as a starting point, but it's often inaccurate and undervalues your claim.
Each state (Florida, Minnesota, Wisconsin) has specific rules for third-party diminished value claims.
Insurance companies rarely offer diminished value unless you request and prove it.
A public adjuster can help maximize your payout and handle the paperwork on your behalf.
Maximize Your Car's Value After an Accident
If your car’s ever been in an accident that wasn’t your fault, you probably already know the repair process is a hassle. But what most people don’t realize? Even after your car is “fixed,” its value takes a hit. That’s what diminished value is all about. It’s the financial loss your car suffers simply because it now has an accident history—and it can seriously affect what your vehicle’s worth down the road.
Insurance companies aren’t in a rush to bring this up. That’s why knowing how to calculate diminished value (and when to push for it) can make a real difference—especially if you’re filing a third-party claim in Florida, Minnesota, or Wisconsin. Let’s break down what this really means, how it works, and what you can actually do about it.
What This Blog Covers:
What diminished value actually is
Why insurers don’t advertise it
How to run the numbers (and why most estimates are off)
The flaws in the standard formula
Key state-specific points for FL, MN, and WI
When it’s worth bringing in a public adjuster
What is Diminished Value?
Diminished value is the drop in resale value your vehicle takes after it's been in an accident, even if it was professionally repaired. The damage might be gone, but the history sticks—and that alone can turn off future buyers or lower trade-in offers. Carfax, AutoCheck, and similar reporting services keep a record of the accident, which follows the vehicle long after the repairs.
There are a few different angles insurers use to define it:
Inherent Diminished Value: This is the default—just the fact that the vehicle has an accident history.
Repair-Related Diminished Value: Comes into play if subpar repairs or cheaper replacement parts reduce the car’s value.
Immediate Diminished Value: Refers to the loss before repairs are even done—usually used in theoretical discussions.
Most of the time, you’re dealing with inherent diminished value—that unavoidable dent to the vehicle’s value post-repair.
"Nearly 7 out of 10 Midwestern drivers have never even heard of a public adjuster, let alone know they can use one to handle their insurance claim.”
Why Insurance Companies Don’t Talk About It
This one’s simple: it costs them. If they can settle your property damage and rental car costs and call it a day, they will. Diminished value claims are often overlooked unless you bring them up—and even then, you’re expected to prove the loss. That’s especially true with third-party claims (when the other driver is at fault). Their insurer has no incentive to go above and beyond unless you force the issue.
How to Calculate Diminished Value
There isn’t a universal calculator for this, but most insurance companies default to a version of the 17c formula—named after a court case in Georgia. It’s widely used, but often criticized for undervaluing claims.
The 17c Formula, Broken Down:
Start with the car’s pre-accident market value.
NADA, Kelley Blue Book, or a dealer estimate can help.
Apply a 10% cap.
Multiply that value by 10%. That becomes your "maximum" diminished value.
Apply a damage multiplier.
1.00 = severe frame/structural damage
0.75 = major damage to structure or panels
0.50 = moderate damage
0.25 = minor damage
0.00 = cosmetic or no damage
Apply a mileage modifier.
<20,000 miles = 1.00
20,000–39,999 = 0.80
40,000–59,999 = 0.60
60,000–79,999 = 0.40
80,000–99,999 = 0.20
100,000+ = 0.00
Example:
Vehicle market value: $25,000
10% cap = $2,500
Moderate damage = x 0.50 = $1,250
60,000 miles = x 0.40 = $500 diminished value
But here’s the problem—
Why the 17c Formula Often Misses the Mark
The 17c formula is convenient for insurers because it consistently produces lower estimates. It doesn't consider:
How much more buyers devalue luxury or sports cars with accident histories
Local market fluctuations (Florida’s resale market isn’t the same as Wisconsin’s)
How well the repairs were actually done (or not done)
That’s why this formula should be viewed as a starting point—not the final word. If your vehicle is rare, high-end, or in high demand where you live, the actual loss could be much more.
Mistakes People Make (and How to Avoid Them)
Not filing a diminished value claim at all. It’s not automatic—you have to request it.
Trusting the insurer’s first number. They’re not legally obligated to give you a fair estimate.
Skipping documentation. You’ll need detailed repair invoices and a fair market value report.
Assuming all states handle it the same. They don’t.
How Florida, Minnesota, and Wisconsin Handle Diminished Value
These three states allow third-party diminished value claims—but that doesn’t mean they make it easy.
Florida: The state recognizes diminished value in third-party claims. The burden’s on you to prove it.
Minnesota: Similar stance. You can file, but expect pushback unless you document the loss clearly.
Wisconsin: Conservative approach. Valid claims are possible, but they require solid proof and negotiation.
In all three, the more organized and informed you are, the better your chances. Some insurers will pay fair value. Others need more convincing.
What a Public Adjuster Brings to the Table
A good public adjuster isn’t just another set of hands—they’re an advocate who knows the insurance system inside and out. At Shoreline Public Adjusters, our job is to level the playing field. We dig into repair records, research real market comps, and present your case in a way that insurance companies respect (or can’t easily ignore).
We work with people across Florida, Minnesota, and Wisconsin, and we’re especially focused on making sure things like diminished value don’t slip through the cracks.
Final Thoughts: Don’t Let the Insurer Call All the Shots
If your car's been in an accident and someone else was at fault, you’re likely owed more than just the cost of repairs. Diminished value matters—and knowing how to calculate it is only the beginning. Make sure you understand your rights, do the math, and don’t hesitate to get help if it starts to feel like a fight.
Reach out to Shoreline Public Adjusters for a free consultation—we’ll help you figure out what your claim is really worth.
Shoreline Public Adjusters, LLC
780 Fifth Avenue South
Suite #200
Naples, FL 34102Email: hello@teamshoreline.com
Phone: 954-546-1899
Fax: 239-778-9889
