MotorMath
Cost of Ownership

Future Car Value Calculator

Project a vehicle's value after any number of years using compound depreciation.

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What this tool does

This calculator projects a vehicle's future value using compound annual depreciation. The user enters the car's current value, an annual depreciation rate (as a percentage), and a time horizon in years; the calculator returns the estimated future value, total value lost, percentage retained, and average loss per year. The compound decay formula applies each year's depreciation to the remaining value, not the original price.

Inputs
(£)
(%)
(yrs)
Result
Result

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Formula
Future car value (£)
Current car value (£)
Annual depreciation rate (decimal)
Time horizon (years)

How Future Car Value Calculator works

This tool estimates what a vehicle will be worth after a specified number of years by applying a constant annual depreciation rate. Unlike straight-line depreciation—which subtracts a fixed amount each year—this calculator uses compound depreciation: each year's percentage loss is applied to the remaining value, not the original purchase price. The output includes the projected future value, total value lost over the period, the percentage of original value retained, and the average loss per year.

The formula

The calculator implements the compound depreciation equation:

Future Value = Current Value × (1 − r)n

where r is the annual depreciation rate (expressed as a decimal) and n is the number of years ahead. For example, a £20,000 car depreciating at 12% per year over 3 years yields £20,000 × (1 − 0.12)³ = £20,000 × 0.681472 ≈ £13,629. The calculator also computes value lost (Current Value − Future Value), retained percentage (Future Value ÷ Current Value × 100), and per-year loss (Value Lost ÷ Years).

Where this method is most accurate

Compound depreciation models work best when the annual rate remains stable across the projection period. In practice, vehicles often lose value faster in early years and slower later. The method assumes no major events—accidents, mechanical failures, market disruptions, or model redesigns—that would cause sudden value changes. Accuracy improves when the depreciation rate is derived from historical data for the specific make, model, age bracket, and mileage profile rather than assumed as a flat industry average.

What this tool does not do

This calculator does not source or embed specific depreciation rates for any make, model, or trim; the user must supply the rate. It does not account for mileage, condition, service history, optional equipment, or local market demand. The projection assumes the rate entered is constant; real-world depreciation curves are rarely linear. The tool does not provide valuation advice, compare models, or indicate whether a vehicle is priced fairly today.

Disclaimer

This calculator is an educational mathematics tool. It performs arithmetic only; it does not appraise vehicles, provide financial advice, or predict actual resale prices. Real-world car values depend on countless factors outside the scope of a fixed-rate formula. Use the output to understand compound depreciation mechanics, not as a guarantee of future value or a substitute for professional appraisal.

Questions

Why does compound depreciation produce a lower future value than straight-line?
Compound depreciation applies the percentage rate to the declining balance each year, so the absolute loss shrinks over time. Straight-line depreciation subtracts the same fixed amount annually, which often overstates early-year losses and understates later resilience for most vehicles.
Where do I find a realistic depreciation rate for my car?
Historical sales data, automotive valuation guides, and manufacturer residual-value forecasts can provide make- and model-specific rates. Average rates range from 8–20% annually, with luxury and electric models often at the higher end and popular mainstream models lower.
Can I use this calculator for classic or collector cars?
The compound-decay model assumes continuous depreciation. Many classics appreciate or stabilize after initial depreciation phases; entering a negative rate is not supported by this calculator. For appreciating assets, other valuation methods are more appropriate.
Does the calculator account for inflation or currency changes?
No. All inputs and outputs are in nominal terms—today's currency units. The depreciation rate entered should be a nominal rate if comparing against nominal prices, or a real (inflation-adjusted) rate if working in constant currency.
How does mileage affect the result?
This tool does not incorporate mileage; it applies a single annual percentage regardless of distance driven. In practice, higher mileage accelerates depreciation. Users may estimate a blended rate that reflects expected annual mileage or use mileage-specific valuation tools separately.

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Sources & Methodology

The calculator applies the compound decay formula Future Value = Current Value × (1 − r)ⁿ, where r is the annual depreciation rate (as a decimal) and n is the number of years. This equation is standard in finance and asset valuation, treating depreciation as exponential decay rather than linear subtraction.

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