Depreciation and refinancing look like unrelated topics, but they meet in the same place: the gap between what a car is worth and what is still owed on it. The car depreciation calculator estimates how much value a vehicle has lost, which is the number that determines whether a loan balance sits above or below the car’s value. The car refinance calculator compares the cash flows of your current loan with a proposed replacement loan. Neither tool models the other’s subject — depreciation has no loan inputs, and refinancing never checks vehicle value — which is exactly why using them together covers the full picture.
What each calculator does
The car depreciation calculator takes an original purchase price, car age in years (decimals allowed), a first-year depreciation rate, and a later annual depreciation rate. For vehicles up to one year old it prorates the first-year rate; after year one it applies the full first-year rate and then compounds the later rate for age minus one years. The outputs are the estimated current value, total depreciation, percent of the original price lost, and the estimated value in one more year. The page is explicit that there is no mileage, condition, or salvage-floor input — the result is entirely rate-based, and actual resale value depends on factors the model does not know.
The car refinance calculator takes the balance left on loan, the remaining term and rate on the current loan, the new term and new rate from a refinance quote, cash out (or cash in) for principal adjustments, and refinance fees that will be financed. It builds the new loan amount from the balance plus cash adjustment plus fees, computes a payment for both loans with the standard amortizing formula, and reports the monthly savings (or monthly increase), current and new total interest, interest savings after fees, total payment savings, and a fee break-even period. The page notes it does not check loan-to-value, mileage, title status, or credit criteria — those are lender underwriting rules.
Side-by-side
| Car depreciation calculator | Car refinance calculator | |
|---|---|---|
| Question | How much value has the vehicle lost? | Does replacing my current loan save money? |
| Inputs | Purchase price, age, first-year and later annual depreciation rates | Current balance, remaining term and rate, new term and rate, cash in/out, refinance fees |
| Primary output | Estimated current value | Monthly savings (or monthly increase) |
| Other outputs | Total depreciation, percent lost, next-year value | New monthly payment, interest savings after fees, total payment savings, break-even months |
| Vehicle value | Modeled from user-entered rates | Not checked — no value or loan-to-value input |
| Loan balance | Not modeled | Current balance compared with the replacement loan |
| Formula basis | Compound percentage loss with a separate first-year rate | Amortizing payment formulas applied to both loans |
When to use which
Use the depreciation calculator when your question is about the vehicle itself: how much value a new or used purchase may lose, when to sell, whether a lease-end buyout makes sense, or how the expected resale value compares with a loan balance. Because the model needs only rates you choose, it is easy to run optimistic, base, and conservative cases — the page recommends exactly that.
Use the refinance calculator when you hold a payoff quote or current balance and a proposed replacement offer. It is the tool for the cash-flow question: does the new loan lower total interest after fees, and is the payment change actually a saving or an increase? The page’s own example shows the trade-off — a shorter, lower-rate loan can raise the monthly payment while cutting remaining interest substantially.
The two tools connect on negative equity. The depreciation estimate gives you a rough current value to hold against the payoff balance: if the car is likely worth less than the loan, that is a signal to check loan-to-value and age limits before assuming a refinance offer exists, since the refinance page notes lenders may apply those rules. And the refinance math itself is value-independent — it compares loan cash flows only. When a new payment is on the table, pressure-test it against insurance, fuel, repairs, and other obligations in the budget calculator.
Limits and disclaimer
Both pages are scenario estimates built from user-entered assumptions, not appraisals, quotes, or lender decisions. The depreciation calculator has no mileage, condition, or salvage-floor input, and its result is not a guaranteed resale value; the refinance calculator does not check loan-to-value, mileage, title, or credit, and it validates that a positive loan amount remains after cash adjustments. Neither page provides tax advice — the depreciation article notes that business vehicle tax depreciation can follow IRS rules that its economic value-loss model does not implement. Both are educational only and not financial advice; review the actual loan documents before refinancing.