17c diminished value calculator: the formula or a market percentage, from verified comps

Worked example: $25,000 pre-loss value, moderate damage, 45,000 miles

17c damage multipliers: none 0.00, minor 0.25, moderate 0.50, major 0.75, severe 1.00. The mileage multiplier steps down from 1.00 (0 to 19,999 miles) to 0.20 (80,000 to 99,999 miles) and 0.00 (100,000 miles and above). Every factor is editable on the worksheet.

Diminished Value Report or Diminished Value Worksheet?

• Build a diminished value worksheet for VIN 4T3R6RFV7MU015349, 42,800 miles, ZIP 60601, moderate damage, repairs were $6,400.

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• My car was repaired after a structural hit and is worth less now. VIN 3GNAXUEG2RS216393, 41,058 miles, ZIP 48120. Use a straight 15% rather than 17c.

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Who runs the Diminished Value Worksheet

• Independent appraisers preparing a diminished value claim after a repair.
• Public adjusters and attorneys who need the pre-loss value built from comparables the carrier cannot wave away.
• Appraisers who consider 17c an undervaluation and would rather argue the loss from the market.

Before you run it

What goes into a diminished value appraisal file?

A pre-loss value, the method and the loss in value, with the evidence behind each. The worksheet builds the pre-loss value from about three like-for-like comparables verified on the dealer page, applies 17c or a straight percentage line by line, and carries a branded Excel and, when you enter the appraiser fields, your certification block.

How does the worksheet support a client's diminished value claim?

It is the written valuation the claim rests on: the pre-loss value from verified comparables, the loss in value by the method you choose, and, when you enter the appraiser fields, your certification with your name, license and file number. The client sends it to the at-fault driver's insurer with the repair records and photos.

What is the 17c formula and why do appraisers dispute it?

17c is a diminished value formula many carriers use. It caps the loss at 10% of the pre-loss value and scales that cap by damage and mileage multipliers, so a car past 100,000 miles gets zero. It is simple to apply; appraisers dispute it because its cap and multipliers are fixed in advance, while buyers' discount for an accident history varies by vehicle and market. The worksheet builds pre-loss value from market comparables and offers 17c or a percentage.

Can I use the worksheet as a 17c diminished value calculator?

Yes. It takes a VIN, odometer, ZIP and damage severity, builds the pre-loss value from about three like-for-like comparables verified on the dealer page, and computes the loss with the 17c formula or a percentage. On the page you can re-pick comparables and change the method, cap, damage severity, multipliers and percentage. Changing the VIN, odometer, ZIP or radius is a re-run: on a prepaid account, $0.99 within 30 days of a full-price run, up to 3 times.

How does the 17c formula work here?

A 10% cap on the pre-loss value is scaled by a damage multiplier (none 0, minor 0.25, moderate 0.50, major 0.75, severe 1.00) and a mileage multiplier. All three are editable on the page. Note that 17c yields zero above 100,000 miles by construction; the worksheet says so plainly and lets you override the multiplier or switch methods.

What is the percent method?

A straight percentage of the comparable-derived pre-loss value, 12% by default and editable. Use it when you can support the loss from the market rather than from a carrier formula. You can switch between the two methods on the hosted page after the run.

Where does the pre-loss value come from?

From about three like-for-like active comparables matched through the VIN pattern and banded to the subject odometer, each verified on the dealer page with a timestamped snapshot and mileage-adjusted to the subject. You pick the comparables; the loss is taken off that figure.

How is this different from the Diminished Value Report?

The report anchors pre-loss value on a model prediction you cannot move and returns a comparable-based figure quickly. The worksheet derives pre-loss value from comparables you select and gives you the certification block, the branded Excel and the read-only copy for the file.

What does it cost?

$5.99 per worksheet, with $0.99 re-runs of the same VIN within 30 days, up to three times. Connect the MarketCheck AI Desk to Claude or ChatGPT once and ask in plain English, or run it from this website. You pay per report from a credit balance, with no subscription.

Want programmatic access to the reports? Technical reference (inputs, outputs, the MCP tool name): Diminished Value Worksheet documentation.

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