Car Affordability Calculator
A car affordability calculator determines how much car you can afford based on your income, down payment, and desired payment. Financial experts recommend keeping total car costs under 15-20% of your take-home pay.
The 20/4/10 Rule
The 20/4/10 rule provides a guideline for car purchases:
- 20% minimum down payment
- 4 year maximum loan term
- 10% maximum of gross income for total car costs (payment + insurance)
Car Affordability by Monthly Income
| Monthly Income | Max Payment (10%) | Max Payment (15%) | Affordable Car (5yr, 7%) |
|---|---|---|---|
| $3,000 | $300 | $450 | $15,000 - $22,500 |
| $4,000 | $400 | $600 | $20,000 - $30,000 |
| $5,000 | $500 | $750 | $25,000 - $37,500 |
| $6,000 | $600 | $900 | $30,000 - $45,000 |
| $8,000 | $800 | $1,200 | $40,000 - $60,000 |
Car Affordability Calculator Implementation
``javascript
function calculateCarAffordability(monthlyIncome, maxPaymentPercent, rate, termYears, downPayment = 0) {
const maxPayment = monthlyIncome * (maxPaymentPercent / 100);
const monthlyRate = rate / 100 / 12;
const payments = termYears * 12;
// Calculate max loan from payment
const maxLoan = maxPayment * (1 - Math.pow(1 + monthlyRate, -payments)) / monthlyRate;
const maxCarPrice = maxLoan + downPayment;
return {
maxPayment: maxPayment.toFixed(2),
maxLoan: maxLoan.toFixed(2),
maxCarPrice: maxCarPrice.toFixed(2),
totalCost: (maxPayment * payments + downPayment).toFixed(2)
};
}
console.log(calculateCarAffordability(5000, 10, 7, 5, 5000));
// { maxPayment: '500.00', maxLoan: '25176.49', maxCarPrice: '30176.49' }
``
Total Cost of Ownership
Remember that car payments aren't your only cost. Include insurance, gas, maintenance, registration, and depreciation in your budget. A cheaper reliable car often costs less than an expensive car with high maintenance.