Car Payment Calculator - Estimate Monthly Auto Loan Costs

Estimate your monthly car payment, total interest, and total loan cost. Our accessible, mobile-first calculator accounts for vehicle price, down payment, trade-in, sales tax, and fees.

Loan Inputs

Sales Tax & Fees (Optional)

Payments are treated as monthly by default.

How to Use This Calculator

Enter the vehicle price, then subtract any down payment and trade-in credit. Layer in the sales tax rate and any other fees you expect to pay. Add the interest rate offered by the lender and the loan term in months, then click Calculate to see the monthly payment, total interest, and overall loan cost.

  • Enter Vehicle Costs down to the last dollar and set the sales tax percentage.
  • Add Credits so the tool knows how much of the total is already covered before financing.
  • Provide Loan Terms including APR and duration in months.
  • Review the monthly payment, total interest, and amortization schedule for clarity on when the loan will retire.

Methodology

The calculator computes the financed principal as the vehicle price plus tax and fees minus any down payment and trade-in credit. It then runs a fixed-rate amortization model to simulate each monthly payment, ensuring the final payment clears the balance.

We treat payments as monthly by default, round every row to two decimals, and show the payoff horizon both as a count of months and a human-readable timeframe.

  • The formula below produces the periodic payment once the principal and monthly interest rate are known.
  • Interest accumulates each month on the remaining balance and is paid down alongside principal.
  • The amortization table projects each month’s interest, principal, and remaining balance so you can trace equity build-up.

Full original guide (expanded)

The legacy page included navigation shortcuts (Advanced Search, Categories) and a sidebar callout to remind readers of the audit context. It also highlighted a 300×600 ad placeholder, reasons to use the calculator, and related automotive tools.

  • Navigation ease: the banner offered Advanced Search and Categories links for digging into more calculators.
  • Sidebar ad placeholder titled “Ad Placement (300×600)” served as a visual reference for future media partners.
  • The sidebar reiterated why this calculator belongs on CalcDomain—covering taxes, down payment, trade-in, amortization visibility, and a mobile-first, accessible design.
  • A related tools panel pointed to the Auto Loan Amortization Schedule, Loan Early Payoff Calculator, Loan Comparison Calculator, and APR Calculator.
Formulas

Financed principal:

$P = (\text{Vehicle Price} + \text{Tax} + \text{Fees}) - (\text{Down Payment} + \text{Trade-in})

Fixed-rate amortization payment:

$M = P \frac{r(1+r)^n}{(1+r)^n - 1}

  • P: principal (total loan amount after credits)
  • r: periodic interest rate (annual APR ÷ 12)
  • n: total number of payments (loan term in months)
  • M: monthly payment toward principal + interest
  • Tax and fees are converted to currency before credits are subtracted.
Citations

Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/

Lifestyle & Everyday — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/categories/lifestyle-everyday

Automotive — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/automotive

Loan Comparison Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/loan-comparison

APR Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/apr

Changelog
  • 0.1.0-draft — 2026-01-19: Initial draft (review required).
✓ Audit: Complete Verified by Ugo Candido Last Updated: 2026-01-19 Version 0.1.0-draft
Version 1.5.0
+ round2(safe).toFixed(2); } }; const formatTerm = (months) => { if (!Number.isFinite(months) || months <= 0) return '—'; const wholeYears = Math.floor(months / 12); const remMonths = months % 12; if (wholeYears <= 0) return `${remMonths} months`; if (remMonths === 0) return `${wholeYears} yrs`; return `${wholeYears} yrs ${remMonths} mos`; }; const defaults = { vehiclePrice: '32000', downPayment: '4000', tradeInValue: '2500', salesTaxRate: '7.5', fees: '1000', interestRate: '5.25', loanTerm: '60' }; const els = { vehiclePrice: document.getElementById('vehiclePrice'), downPayment: document.getElementById('downPayment'), tradeInValue: document.getElementById('tradeInValue'), salesTaxRate: document.getElementById('salesTaxRate'), fees: document.getElementById('fees'), interestRate: document.getElementById('interestRate'), loanTerm: document.getElementById('loanTerm'), monthlyPayment: document.getElementById('monthlyPayment'), totalPrincipal: document.getElementById('totalPrincipal'), totalInterest: document.getElementById('totalInterest'), totalCost: document.getElementById('totalCost'), payoffTime: document.getElementById('payoffTime'), errorBox: document.getElementById('errorBox'), scheduleWrap: document.getElementById('scheduleWrap'), scheduleBody: document.getElementById('scheduleBody'), toggleSchedule: document.getElementById('toggleSchedule'), downloadCsv: document.getElementById('downloadCsv'), calcBtn: document.getElementById('calcBtn'), resetBtn: document.getElementById('resetBtn') }; let currentSchedule = []; const applyDefaults = () => { els.vehiclePrice.value = defaults.vehiclePrice; els.downPayment.value = defaults.downPayment; els.tradeInValue.value = defaults.tradeInValue; els.salesTaxRate.value = defaults.salesTaxRate; els.fees.value = defaults.fees; els.interestRate.value = defaults.interestRate; els.loanTerm.value = defaults.loanTerm; }; function parseInputs() { const toNumber = (value) => { const parsed = parseFloat(String(value).replace(/,/g, '').trim()); return Number.isFinite(parsed) ? parsed : 0; }; return { vehiclePrice: toNumber(els.vehiclePrice.value), downPayment: toNumber(els.downPayment.value), tradeInValue: toNumber(els.tradeInValue.value), salesTaxRate: toNumber(els.salesTaxRate.value), fees: toNumber(els.fees.value), interestRate: toNumber(els.interestRate.value), loanTerm: parseInt(els.loanTerm.value, 10) || 0 }; } function validate(inputs) { const errors = []; if (!Number.isFinite(inputs.vehiclePrice) || inputs.vehiclePrice <= 0) errors.push('Vehicle price must be greater than 0.'); if (!Number.isFinite(inputs.interestRate) || inputs.interestRate < 0) errors.push('Interest rate must be 0 or greater.'); if (!Number.isFinite(inputs.loanTerm) || inputs.loanTerm <= 0) errors.push('Loan term must be greater than 0.'); if (!Number.isFinite(inputs.downPayment) || inputs.downPayment < 0) errors.push('Down payment must be 0 or greater.'); if (!Number.isFinite(inputs.tradeInValue) || inputs.tradeInValue < 0) errors.push('Trade-in value must be 0 or greater.'); if (!Number.isFinite(inputs.salesTaxRate) || inputs.salesTaxRate < 0) errors.push('Sales tax rate must be 0 or greater.'); if (!Number.isFinite(inputs.fees) || inputs.fees < 0) errors.push('Fees must be 0 or greater.'); return { ok: errors.length === 0, errors }; } function buildSchedule(principal, monthlyRate, termMonths, monthlyPayment) { const schedule = []; let balance = principal; const maxIter = termMonths + 12; for (let i = 1; i <= maxIter && balance > 0.005; i++) { const interest = monthlyRate === 0 ? 0 : balance * monthlyRate; let principalPaid = monthlyRate === 0 ? monthlyPayment : monthlyPayment - interest; if (principalPaid < 0) break; let payment = monthlyPayment; if (i === termMonths || balance - principalPaid <= 0) { principalPaid = balance; payment = principalPaid + interest; } balance -= principalPaid; schedule.push({ month: i, payment: round2(payment), interest: round2(interest), principal: round2(principalPaid), balance: round2(Math.max(0, balance)) }); } return schedule; } function compute(inputs) { const taxRate = inputs.salesTaxRate / 100; const totalTax = inputs.vehiclePrice * taxRate; const totalCostBeforeCredits = inputs.vehiclePrice + totalTax + inputs.fees; const credits = inputs.downPayment + inputs.tradeInValue; const principal = Math.max(0, totalCostBeforeCredits - credits); if (principal <= 0) { return { monthlyPayment: 0, totalPrincipal: 0, totalInterest: 0, totalCost: 0, totalPayments: 0, schedule: [] }; } const termMonths = Math.round(inputs.loanTerm); if (termMonths <= 0) return null; const monthlyRate = inputs.interestRate / 100 / 12; let monthlyPayment; let totalInterest; if (monthlyRate === 0) { monthlyPayment = principal / termMonths; totalInterest = 0; } else { const factor = Math.pow(1 + monthlyRate, termMonths); monthlyPayment = principal * (monthlyRate * factor) / (factor - 1); totalInterest = monthlyPayment * termMonths - principal; } const schedule = buildSchedule(principal, monthlyRate, termMonths, monthlyPayment); const roundedPayment = round2(monthlyPayment); const roundedPrincipal = round2(principal); const roundedInterest = round2(totalInterest); const roundedCost = round2(principal + totalInterest); return { monthlyPayment: roundedPayment, totalPrincipal: roundedPrincipal, totalInterest: roundedInterest, totalCost: roundedCost, totalPayments: schedule.length, schedule }; } function formatResults(outputs) { if (!outputs) return null; return { monthlyPayment: fmtCurrency(outputs.monthlyPayment), totalPrincipal: fmtCurrency(outputs.totalPrincipal), totalInterest: fmtCurrency(outputs.totalInterest), totalCost: fmtCurrency(outputs.totalCost), payoffTime: outputs.totalPayments > 0 ? formatTerm(outputs.totalPayments) : '—' }; } function renderError(errors) { if (!errors || errors.length === 0) { els.errorBox.style.display = 'none'; els.errorBox.textContent = ''; return; } els.errorBox.style.display = 'block'; els.errorBox.textContent = errors.join(' '); } function renderTable() { els.scheduleBody.innerHTML = ''; const rows = currentSchedule.slice(0, 360); const frag = document.createDocumentFragment(); for (const row of rows) { const tr = document.createElement('tr'); tr.innerHTML = ` ${row.month} ${fmtCurrency(row.payment)} ${fmtCurrency(row.interest)} ${fmtCurrency(row.principal)} ${fmtCurrency(row.balance)} `; frag.appendChild(tr); } els.scheduleBody.appendChild(frag); } function render(formatted, errors) { renderError(errors); if (!formatted) return; els.monthlyPayment.textContent = formatted.monthlyPayment; els.totalPrincipal.textContent = formatted.totalPrincipal; els.totalInterest.textContent = formatted.totalInterest; els.totalCost.textContent = formatted.totalCost; els.payoffTime.textContent = formatted.payoffTime; els.downloadCsv.disabled = currentSchedule.length === 0; if (els.scheduleWrap.style.display === 'block') { renderTable(); } } function update() { const inputs = parseInputs(); const validation = validate(inputs); if (!validation.ok) { currentSchedule = []; render(null, validation.errors); els.downloadCsv.disabled = true; return; } const outputs = compute(inputs); if (!outputs) { currentSchedule = []; render(null, ['Calculation failed for the current inputs. Please revise values.']); els.downloadCsv.disabled = true; return; } currentSchedule = outputs.schedule; render(formatResults(outputs), []); } const debouncedUpdate = (function () { let timer; return function () { clearTimeout(timer); timer = setTimeout(() => update(), 100); }; })(); el.addEventListener('change', debouncedUpdate); }); els.calcBtn.addEventListener('click', update); els.resetBtn.addEventListener('click', () => { applyDefaults(); const debouncedUpdate = debounce(update, 100); document.querySelectorAll('#inputsCard input, #inputsCard select, #inputsCard textarea') .forEach((el) => { el.addEventListener('input', debouncedUpdate); el.addEventListener('change', debouncedUpdate); }); update(); }); els.toggleSchedule.addEventListener('click', () => { const isHidden = els.scheduleWrap.style.display !== 'block'; els.scheduleWrap.style.display = isHidden ? 'block' : 'none'; els.toggleSchedule.textContent = isHidden ? 'Hide Amortization Schedule' : 'View Amortization Schedule'; if (isHidden) renderTable(); }); els.downloadCsv.addEventListener('click', () => { if (!currentSchedule.length) return; let csv = '#,Payment,Interest,Principal,Balance\n'; for (const row of currentSchedule) { csv += `${row.month},${row.payment},${row.interest},${row.principal},${row.balance}\n`; } const blob = new Blob([csv], { type: 'text/csv' }); const url = URL.createObjectURL(blob); const link = document.createElement('a'); link.href = url; link.download = 'car-loan-amortization.csv'; link.click(); URL.revokeObjectURL(url); }); applyDefaults(); update(); })();