THE NUMORIX GUIDE
How to use the Auto Depreciation Calculator
Last reviewed September 14, 2026
What this calculator does
The route applies a constant annual percentage to the current modeled vehicle value: depreciation for year t is value at the start of the year x depreciationRate/100, followed by value = prior value x (1 - depreciationRate/100).
Formula and method
The route applies a constant annual percentage to the current modeled vehicle value: depreciation for year t is value at the start of the year x depreciationRate/100, followed by value = prior value x (1 - depreciationRate/100). It runs through the requested age, rounds each displayed yearly value to a whole dollar, and reports current value, total depreciation, and percentage loss.
Variables and inputs
Enter Purchase Price, Vehicle Age in years, and Annual Depreciation as a percentage. The UI accepts a positive purchase price, nonnegative age, and a rate from 0% through 100%. The engine's age-based result is a modeled value, not a vehicle appraisal or a tax basis.
Worked example
For a $35,000 purchase price, age 5, and 15% annual depreciation, modeled value is 35,000 x 0.85^5 = $15,529.69, displayed as about $15,530. Total modeled depreciation is $19,470, or about 55.6% of the purchase price.
How to interpret the result
This is declining-balance arithmetic: each year's dollar loss gets smaller because the percentage is applied to a smaller modeled value. The result can show the sensitivity of a vehicle scenario to an assumed rate, but it does not identify what a buyer or dealer will actually pay today.
Common mistakes to avoid
Enter 15 for 15%, not 0.15. Use the original purchase price as the starting value and keep age in years. Do not confuse this repeated percentage model with the IRS tax depreciation rules or with a market value forecast based on mileage and condition.
Assumptions and limitations
The engine uses one constant rate and does not model vehicle make, mileage, condition, supply and demand, incentives, taxes, financing, salvage value, or a real resale database. It is not an accounting or tax schedule, and its whole-dollar display rounding can differ slightly from an unrounded calculation.