How Much Car Can You Afford? The 20/4/10 Rule
A car is one of the biggest budget-wreckers there is — not because of the sticker price, but because of the payment. Here's a simple rule to keep your wheels from running over your finances.
The 20/4/10 rule
It's an easy guideline for buying a car without overextending yourself:
- 20% down. Put at least 20% down to avoid being "underwater" (owing more than the car is worth).
- 4-year loan max. Finance for no longer than four years. If you need a longer loan to afford the payment, the car is too expensive.
- 10% of income. Keep your total monthly transportation costs — payment plus insurance — under 10% of your gross monthly income.
Why it works
Long loans are how dealerships sell you "more car" by stretching the payment over six or seven years. But the longer the loan, the more interest you pay and the longer you owe more than the car is worth. The 20/4/10 rule keeps you in a vehicle you actually own sooner, with payments that leave room for saving and investing — not just servicing a depreciating asset.
The true cost of ownership
The payment is only part of the story. Budget for the whole picture:
- Insurance — often hundreds per month depending on your area and record.
- Fuel or charging — varies with your commute.
- Maintenance and repairs — tires, oil, brakes, and the occasional surprise.
- Registration, taxes, and depreciation — a new car can lose a big chunk of value in the first few years.
This is why a slightly used car is often the savvy move: you let someone else absorb the steepest depreciation, and a reliable two- to four-year-old vehicle can save you thousands.
Smart car-buying tips
- Get pre-approved for financing from your bank or credit union before visiting the dealer, so you can compare their offer.
- Negotiate the total price, not the monthly payment. Payment-focused negotiation hides a longer term or higher rate.
- A better credit score means a lower rate — worth improving before you shop.
- Skip pricey add-ons you don't need at the finance desk.
General educational information, not financial advice. See our disclaimer.