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Where the numbers come from
Nothing on these pages is from memory. Each fact below has a source we opened, twice, on 2026-11-02. Each formula has a test.
Sources
Rent charge = money factor x (adjusted cap cost + residual)
Source Federal Reserve, Vehicle Leasing: More Information about the Rent Charge · opened twice on 2026-11-02, same text both times
The page says the money factor is multiplied by the sum of the adjusted capitalized cost and the residual value, and works the example .00354 x ($18,800 + $12,350) = $110.27. It also says a money factor is not a lease rate and cannot be converted by moving the decimal point, and that it typically is not disclosed to you.
How we use it Reproduced: our calculator returns $110.27 for that example.
Depreciation = adjusted cap cost minus residual
Source Federal Reserve, Vehicle Leasing: Leasing vs. Buying: Monthly Payments · opened twice on 2026-11-02, same text both times
The page says that in vehicle leasing, depreciation is the difference between the agreed value of the vehicle minus any capitalized cost reduction, and the residual value at lease end. Taxes and fees included in the gross cap cost are paid off over the term as well.
How we use it We spread (cap cost minus residual) evenly over the term. Fees you roll in are part of the cap cost.
Rent charge is similar to interest
Source Federal Reserve, Vehicle Leasing: Frequently Asked Questions · opened twice on 2026-11-02, same text both times
The FAQ says lease payments include rent charges, similar to interest on a loan, and that most lessors use a money factor to calculate them. It also says there is no federal requirement for lessors to disclose a lease rate.
How we use it This is why the lease page asks you to ask for the money factor by name.
Money factor x 2,400 is about the APR
Source Capital One Auto Navigator and Moneyzine · opened twice on 2026-11-02, same text both times
Capital One's lease guide converts a money factor of 0.00125 to 3% by multiplying by 2,400. Moneyzine gives the same rule in both directions.
How we use it A rule of thumb from lenders' guides, not a figure a lessor has to disclose. The Federal Reserve page above warns you cannot just move the decimal point. We label it "about" everywhere.
Also Moneyzine, Money factors in car leases: the same 2,400 rule, shown as a two-way formula. Opened twice on 2026-11-02.
Math, not a quoted fact
Out-the-door total. Price minus trade-in and rebates, plus sales tax, plus fees. The tax rate and every fee are numbers you type from your quote. We do not guess them.
Loan payment. The standard loan formula: principal × monthly rate ÷ (1 − (1 + monthly rate)−months). A 0% loan is the price divided by the months.
Lease vs buy. Both sides are added up over the same months. The car's value at the end is your estimate.
The checks we ran
- The Federal Reserve rent-charge example: $110.27. Matches.
- A $20,000 loan at 6% for 60 months: $386.66 a month, $12,709.78 still owed after 24 months. Matches a separate Python calculation.
- An out-the-door example worked by hand, with the tax on the full price ($26,750) and after the trade-in and rebate ($26,330). Matches.
- A lease example and a lease-vs-buy example, each worked out in separate Python code. Match.
- Bad input: a zero-month lease and a zero cap cost are refused instead of showing a wrong number.
The tests are in tests/calc.test.js in the site's source and run with node.
What is not sourced yet
Sales tax rates, doc fees, title and registration costs differ by state. We do not show any of them yet, because we have not checked them against the states' own pages. You type the numbers from your quote. State pages will come later, and each figure on them will link to the state page it came from.
Found a number that looks wrong? Email support@playriot.co. We fix errors on the page and say so.
These calculators run in your browser and send nothing you type anywhere. The DealShield app's privacy policy is at /privacy.