AutoMath

All 25 calculators

Full index. Each entry links to the calculator and, where one exists, to the cornerstone guide. Looking for a specific question? See the category overview instead.

Financing

What the car really costs to borrow.

  1. Auto Loan Calculator

    Monthly payment, total interest over the loan, and a month-by-month amortization schedule. Supports trade-in, down payment, and sales tax.

    Best when financing a car or comparing loan offers.

  2. Lease vs Buy Calculator

    Compares the all-in cost of leasing against buying-and-keeping the same vehicle, including residual value, depreciation, and the cost of capital.

    Best when deciding between a lease and a purchase.

  3. Car Affordability Calculator

    Works backward from income, existing debt, and a sane payment-to-income ratio to the car price you can actually carry — not the one the dealer approves you for.

    Best before you walk into a dealership.

  4. Auto Loan Early Payoff

    Shows how much interest you save and how many months you cut by adding a fixed extra amount to each payment, or paying a lump sum now.

    Best when you have spare cash and a car loan.

  5. Auto Loan Refinance

    Compares your current auto loan against a refi offer — exact interest saved, monthly payment delta, and the months it takes to recoup the refi fees.

    Best when shopping a lower rate or shorter term on an existing loan.

  6. 0% APR vs Cash Rebate

    Total cost of taking the 0% APR promo on the full price versus taking the cash rebate and financing the smaller balance at your market APR — head-to-head.

    Best when the dealer forces a choice between two promos.

  7. Cash vs Finance Calculator

    Weighs paying cash against financing and keeping the money invested — total interest versus investment earnings — and finds the return at which the two options break even.

    Best when you have the cash but a loan is on the table.

  8. Out-the-Door Price Calculator

    Turns a negotiated vehicle price into the true out-the-door total: sales tax (with or without trade-in credit), dealer doc fee, registration, and add-ons — and the markup over sticker.

    Best when comparing dealer quotes or budgeting the real cash needed.

  9. Upfit Cost Calculator

    Prices a service body, ladder rack, shelving, or liftgate three ways — rolled into the vehicle loan, paid in cash, or on its own equipment note — including the interest it carries and what comes back at resale.

    Best when speccing a work vehicle or a fleet order.

  10. Negative Equity Calculator

    Shows whether you owe more than your car is worth, how much negative equity rolls into a new loan, and the extra payment and interest that carry-over creates.

    Best when trading in a car you still owe money on.

  11. Lease Buyout

    All-in cost to buy out your lease at the contract residual (price + tax + fees) compared to the car's current used-market value. Positive equity ⇒ buy; negative ⇒ return.

    Best at lease end when deciding whether to keep the car.

  12. Early Lease Exit

    Weighs your lease equity (market value − payoff) against the payments, disposition fee, and mileage bill you stop paying by leaving. Compares a third-party buyout against buying the car out and reselling it yourself.

    Best when you're mid-lease and want out before term.

  13. Lease Payment Calculator

    Builds a lease payment the way the dealer does — depreciation plus the money-factor rent charge plus tax — and splits out exactly how much of each payment is interest.

    Best when checking a lease quote or building your own deal.

  14. Lease Mileage Overage

    Projects whether your real driving blows the lease's mileage cap, the excess charge it triggers at turn-in, and whether buying extra miles up front is cheaper.

    Best when you drive a lot and are mid-lease or signing one.

Running Costs

What it costs to keep it on the road.

  1. Fuel Cost Calculator

    What a specific trip or a full year of driving actually costs in fuel, given your real MPG, annual miles, and local gas price.

    Best when planning a road trip or budgeting annual driving.

  2. EV Charging Cost Calculator

    Cost to charge an EV at home or public rates — per session, per mile, and per year — including charging losses and battery size.

    Best when comparing an EV's running cost to gas.

  3. True Cost of Ownership

    What a car actually costs per year and per mile after depreciation, fuel, insurance, maintenance, and the foregone investment return — not the sticker price.

    Best when deciding new vs used, or whether a car earns its keep.

  4. Cost Per Mile Calculator

    The true cost of a mile: fuel, depreciation, insurance, maintenance, and fees, split into fixed and variable — so you can compare it against the IRS standard rate.

    Best when setting a mileage rate or sizing real driving cost.

  5. MPG / Gas Mileage Calculator

    Turns the miles and gallons from one fill-up into your real-world MPG — not the EPA estimate — plus cost per mile, L/100km, and what a year of driving burns in fuel.

    Best when checking real economy or comparing two cars.

  6. Mileage Reimbursement

    Computes the federal mileage reimbursement / deduction for business driving at the current IRS standard rate, with a breakdown by trip log.

    Best when self-employed or claiming business mileage.

The Car Itself

Depreciation, EV math, tires, towing.

  1. Car Depreciation Calculator

    Projects a vehicle's value year by year using a configurable depreciation curve, including the year-one cliff and brand-specific retention.

    Best when timing a sale or estimating equity.

  2. Gas vs Electric Total Cost

    Side-by-side total cost of an internal-combustion car vs an equivalent EV over your ownership period — purchase, energy, maintenance, incentives.

    Best when cross-shopping a gas car against an EV.

  3. New vs Used Car Calculator

    Compares the true cost of a new car against a used equivalent over your hold — depreciation, maintenance, and insurance — and prices the premium you pay to buy new.

    Best when deciding whether the new-car premium is worth it.

  4. Tire Size Calculator

    Converts tire size notation to real dimensions and computes the speedometer error and revs-per-mile change when switching to a different size.

    Best before buying replacement or plus-size tires.

  5. Towing Capacity & Payload

    Checks a trailer + cargo + passenger load against a vehicle's tow rating, GVWR, and payload — including tongue weight — to flag an over-limit setup.

    Best before towing a trailer, boat, or camper.

Don't see what you need?

We're adding calculators each month. On the roadmap: insurance cost by driver profile, registration and title fees by state, maintenance cost by mileage band, and dealer add-on break-even. If there's a specific car-cost calculation you want and we don't have it yet, it's likely already on that list.