Car Value Calculator

This calculator applies a declining-balance depreciation model -- each year multiplies the running value by (1 - 15%) = 0.85, so the age factor is 0.85 raised to the power of the car's age. That kind of exponential decay gets very small for old vehicles (a 20-year-old car retains only about 0.85^20 ≈ 3.9% of its age-based value) but mathematically never touches zero, which mirrors how real used-car markets behave -- depreciation curves flatten out over time rather than hitting a hard floor. A straight-line model that subtracted a fixed percentage of the ORIGINAL price every year would eventually need to floor at zero or go negative; this compounding approach avoids that entirely.

Yes -- Original Purchase Price is a direct multiplier in the formula, so a car that originally cost twice as much will show an estimated current value exactly twice as high, given identical age, mileage, and condition inputs. It's the single largest lever in the calculation since every other factor is a percentage applied against this base figure.

In this calculator's model, mileage depreciation is scaled modestly -- about a 1% value reduction for every 12,000 total miles on the odometer (so a car with 60,000 miles sees roughly a 5% mileage-based reduction) -- which is a smaller effect than the compounding 15%-per-year age penalty for a typical vehicle in this calculator's default ranges. Both factors reduce value independently and multiplicatively against the original price, so a car that's both old AND high-mileage takes a compounded hit from both.

Condition is applied as a multiplier running from 0.65x for Poor up to 1.2x for Excellent, centered on 1.0x for Good (the default), so an otherwise-identical car rated Excellent is estimated at roughly 1.85 times the value of the same car rated Poor, holding age, mileage, and original price constant. That's a deliberately blunt model -- real-world condition assessments weigh mechanical issues, cosmetic damage, and accident history very differently -- but it captures the basic principle that condition materially changes resale value without swinging the estimate as wildly as scaling all the way down to zero at Poor would.