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Car Loan Calculator

Enter loan amount, nominal rate, term and fees to get the monthly payment and the real annualized rate.

Car finance quotes are fond of friendly numbers: "3% a year", "zero interest for two years". Add an arrangement fee, a service charge and the extras, and the real cost changes shape — car loans are where the low-rate illusion lives. Enter the amount, the quoted rate, the term, the fee and any other charges, and the monthly payment and total interest come back alongside the true annualised rate recovered from the cash flows.

The point of the IRR is that fees are either deducted at drawdown or folded into the monthly payment, and a nominal rate cannot express that cost at all. The IRR converts the actual cash flows — what you receive against what you repay — into a comparable annualised figure, which is the only way to rank "interest-free but with a fee" against "5% with no fee". A quoted 3% car rate typically works out nearer 5.5%–6% once fees are counted.

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How to use

  1. Enter the loan amount, the quoted annual rate and the number of monthly payments.
  2. Add the arrangement fee and any other charges.
  3. Read the monthly payment, the total interest and the true annualised rate (IRR).
  4. Compare the IRR across offers rather than the headline rates.

How it works

Monthly payment and total interest formulas

The monthly payment uses the equal-installment method: payment = loan x monthly rate x (1 + monthly rate)^periods / ((1 + monthly rate)^periods - 1). For example 150,000 over 36 periods at a 4.5% nominal annual rate is 4,462.04 per month, with total interest about 10,600.

Why the real APR exceeds the nominal rate

The real APR is reverse-engineered from cash flows (IRR): initially you actually receive "loan - fees," then pay a fixed payment each period; solving that cash-flow series for its internal rate and annualizing it gives the real APR. For 150,000 over 36 periods at 4.5% nominal with a 3% fee plus 2,000, the real APR is about 7.74%, far above the nominal rate.

How to enter fees and subsidies

The fee rate is charged as a percentage of the loan amount; entering "3" means 3%. Fixed-amount service fees, GPS fees and guarantee fees go in "other fees." For a manufacturer-subsidized (0-rate) plan, enter 0 as the nominal rate and include the actual fees charged to see the true cost of the subsidy.

Code example

JavaScript Back-solving the real annual rate with IRR 

function irr(cashflows, guess = 0.1) {   // monthly cashflows, returns a monthly rate
  let r = guess;
  for (let i = 0; i < 100; i++) {
    let f = 0, df = 0;
    cashflows.forEach((cf, t) => {
      f += cf / Math.pow(1 + r, t);
      df += -t * cf / Math.pow(1 + r, t + 1);
    });
    r -= f / df;                          // Newton iteration
  }
  return r;
}
// Real annual rate = (1 + monthly IRR)^12 - 1; cashflows[0] is the amount received (negative)

Python One line with numpy_financial 

# pip install numpy-financial
import numpy_financial as npf

# cashflows: the amount received (negative) + each repayment (positive)
monthly_irr = npf.irr([-97000, 4500] * 1 + [4500] * 23)
annual = (1 + monthly_irr) ** 12 - 1

# On a 2-year car loan with a 3% nominal fee, the real annual rate is often above 5.5%

FAQ

Is such a big gap between nominal rate and real APR normal?

Yes. The nominal rate counts only interest, while fees are deducted up front at disbursement — you actually receive less but repay the full amount, so the cost of funds is pushed up. The shorter the term and the higher the fee, the wider the gap.

Which is better, equal-installment or equal-principal?

Equal-principal pays less total interest but higher early payments; equal-installment has a fixed, balanced payment. Car loans usually run 3-5 years, where the total interest difference is modest — prioritize whether you can afford the payment.

Is 0-rate car financing really cost-free?

Usually not. A 0 rate is often recovered through "fees," "service charges," or reduced price discounts, and may be limited to certain models and terms. Enter the fees here and compare real APRs against other options.

Does prepayment save interest?

It reduces future interest, but some contracts charge a penalty of a percentage of the remaining principal, or require a minimum number of payments before prepaying. Confirm the terms, then estimate savings with the mortgage prepayment calculator using the same convention.

Can it handle interest-only or balloon loans?

This tool computes the payment on an equal-installment basis (fixed each period); interest-only and balloon structures (interest-only early, large principal at the end) don't apply, and using it would understate the real APR. For such plans, request the repayment schedule from the lender and compute from cash flows yourself.

Is financing a car better than paying cash?

Compare the loan rate with the opportunity cost of your funds: if your cash can reliably earn above the real APR, keeping cash and financing is better; if returns are below the real APR or fees are high, cash saves more. Don't look only at the nominal rate — enter the fees and find the real APR first.

How do I verify the dealership's "bundle discount"?

Break the discount into three parts: the direct price cut, the interest subsidy (equivalent to bearing interest for you), and the attached conditions (in-store registration, designated insurance, accessories or a specified finance plan). Conditions often claw the discount back — include fees, service charges and mandatory accessories in the cost and compare real APRs.

Does car-loan calculation need an ID or credit report?

No, and it shouldn't. This tool needs only the loan amount, rate and fees to compute the payment and real APR — no ID, phone number, credit report or any real-name information. Your numbers aren't uploaded, and we can't query any institution for you — be wary of any page that asks for an ID before showing an amount.

Cash has a discount and financing has another — how to compare the two prices?

Treat the "financing-only price discount" as a benefit and "fees + mandatory spending" as a cost, and compare on one timeline. For example a financing price 8,000 lower, but 4,500 in fees and 2,000 more for designated insurance, nets only 1,500 while carrying 3 years of debt — cash wins here. Enter the fees here and see whether the real APR justifies borrowing for that gap.

Long or short loan term?

A longer term lowers the payment but clearly raises total interest. For 150,000 at 4.5% with no fees: 36 periods is 4,462.04 per month and 10,633.39 total interest; 60 periods drops to 2,796.45 per month but 17,787.17 total interest, 7,153.78 more. The only test: can you reliably earn above the real APR on that 1,665 monthly difference? If yes, longer is better; if not, choose shorter.

Can I get a car loan with overdue credit history?

It depends on the number, length and recency of the overdue items: occasional, settled, older overdrafts often still get approved by a bank or captive finance, but at a higher rate and possibly a higher down payment; consecutive overdrafts in the past two years or a current one will likely be rejected. This tool involves no credit approval and has no credit data — it's purely mathematical. Compare quotes by real APR to avoid being pushed into costlier products.