How it works
This is an economic ownership-cost model. Paying the purchase principal acquires an asset; depreciation measures how much of that value is consumed. Counting the full purchase price or every principal payment on top of depreciation would double-count the car. The model therefore includes depreciation and financing interest separately.
Fuel, insurance, maintenance, and recurring taxes or registration are entered as annual averages. Upfront purchase fees are added once and assumed paid in cash. Interest is taken from the modeled loan schedule only for the selected ownership period. If the loan is longer than that period, the remaining balance is displayed for planning the sale.
The formula behind the estimate
Every result starts with a defined model and visible assumptions.
Total cost = purchase price − resale value + years × (annual fuel + insurance + maintenance + recurring fees) + upfront taxes/fees + interest paid during ownership Annual fuel = annual miles ÷ US mpg × price per US gallon
A worked example
For a $20,000 cash purchase sold for $10,000 after five years, depreciation is $10,000. At 12,000 miles per year, 30 US mpg, and $3 per gallon, fuel totals $6,000. Add $6,000 insurance, $3,000 maintenance, $500 recurring fees, and $1,000 upfront costs: total economic cost is $26,500, or about $442 per month.
Build a realistic input set
Use an expected negotiated price and a conservative resale estimate. Put sales tax, title costs, and cash-paid acquisition fees in the upfront field. Do not include them again in purchase price. For recurring fees, use the registrations or vehicle taxes you expect to pay during each year. State rules are not inferred by this calculator.
Fuel price and insurance defaults are examples, not current averages or quotes. Fuel consumption can vary with traffic, weather, trip length, driving style, and loading. An annual repair allowance is a budget reserve rather than a prediction that repairs will occur evenly. If a major service is already due, include it in your planning rather than smoothing it away without explanation.
Economic cost and cash flow answer different questions
The average monthly result helps compare vehicles, but it is not a monthly bill. Down payment and fees may be due immediately; repairs arrive unevenly; resale proceeds arrive only when you sell. Keep an emergency fund and separately check whether each month’s loan payment and running expenses fit your actual household cash flow.
The model excludes inflation, investment returns on cash, parking, tolls, charging, business tax deductions, and unusual disposal costs unless you deliberately include suitable amounts in an annual allowance. If resale exceeds purchase price, depreciation becomes negative; review that assumption carefully. A zero annual distance produces no per-mile estimate rather than dividing by zero.
Questions worth asking
Why isn’t the entire loan payment added?
Principal repayment changes your debt and equity; depreciation already accounts for the vehicle value consumed. Only interest is an additional financing cost in this model.
Does the down payment affect the total?
It affects the amount borrowed and therefore interest. With a zero-rate loan and no other changes, shifting principal between cash and borrowing does not change economic cost.
What if I sell before the loan ends?
The tool counts interest during ownership and shows the remaining balance. Sale proceeds may need to settle that balance; this settlement is not another depreciation expense.
Are maintenance estimates reliable predictions?
No. Enter a reserve based on inspection findings and service requirements, then test higher-cost scenarios. Actual repairs can be lumpy and uncertain.
Can this compare electric vehicles?
The current fuel model uses US mpg and liquid-fuel prices. It does not calculate kWh consumption; do not treat its fuel result as an EV charging estimate.
This is general information, not personalized financial advice. Read the limitations.
