Page published November 4, 2026
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Same car, two paychecks. The 15% line moves with take-home pay, the car does not.
The test, in one line
Pete the Planner's ideal budget keeps total household transportation under 15% of take-home pay, and that category includes gas, insurance, and maintenance. Take-home pay is your pay after taxes and deductions. The test on this page is simple: multiply your monthly take-home pay by 0.15, and that is your transportation line. Inside the line on this page: payment, insurance, fuel, and maintenance. Outside the line: parking, tolls, and the car's loss in value. Parking and tolls are real costs, but they are not part of the rule as stated here, and value loss is not a monthly cash payment.
The example car, priced per month
The car is the 2026 Hyundai Elantra SE from the site's Elantra door: $23,870, 35 miles per gallon, 12,000 miles a year, gas at $4.071 a gallon, the EIA national average, week ending August 31, 2026, insurance at $2,255 a year, maintenance and repairs at $452 a year, and a payment of $487.73 a month on $24,054 financed at 8% APR over 60 months. Turned into monthly figures, each rounded to the cent:
| Monthly cost | Amount |
|---|---|
| Payment | $487.73 |
| Insurance ($2,255 a year divided by 12) | $187.92 |
| Fuel (12,000 miles divided by 35 mpg times $4.071, divided by 12) | $116.31 |
| Maintenance ($452 a year divided by 12) | $37.67 |
| All-in monthly cost | $829.63 |
The sum: $487.73 plus $187.92 plus $116.31 plus $37.67 equals $829.63 a month. That is the number the test runs against.
Formula
The test is one line: multiply your monthly take-home pay by 0.15, and that is your transportation line. Inside the line on this page: payment, insurance, fuel, and maintenance. Outside the line: parking, tolls, and the car loss in value. Take-home pay is your pay after taxes and deductions.
The example car is the 2026 Hyundai Elantra SE from the site Elantra door: $23,870, 35 miles per gallon, 12,000 miles a year, gas at $4.071 a gallon, the EIA national average, week ending August 31, 2026, insurance at $2,255 a year, maintenance and repairs at $452 a year, and a payment of $487.73 a month on $24,054 financed at 8% APR over 60 months. Turned into monthly figures, each rounded to the cent: payment $487.73, insurance $2,255 a year divided by 12, which is $187.92, fuel 12,000 miles divided by 35 miles per gallon times $4.071, divided by 12, which is $116.31, and maintenance $452 a year divided by 12, which is $37.67. The sum is $487.73 plus $187.92 plus $116.31 plus $37.67, which equals $829.63 a month.
The test at two incomes: at $4,000 of take-home pay the line is $600.00 a month and the car at $829.63 a month fails by $229.63; at $6,000 the line is $900.00 and the same car passes by $70.37. The take-home pay this car needs to pass is $829.63 divided by 0.15, which is $5,530.87 a month. The payment that fits each paycheck, after insurance, fuel, and maintenance are taken out of the line, is $258.10 at $4,000 of take-home pay and $558.10 at $6,000 of take-home pay.
The test at two incomes
Same car, two paychecks. The line moves with take-home pay, the car does not.
| Monthly take-home pay | 15% line | Car | Result |
|---|---|---|---|
| $4,000 | $600.00 | $829.63 | Over by $229.63, fails |
| $6,000 | $900.00 | $829.63 | Under by $70.37, passes |
Two more ways to read the same test. The take-home pay this car needs to pass is $829.63 divided by 0.15, which is $5,530.87 a month. And the payment that fits each paycheck, after insurance, fuel, and maintenance are taken out of the line, is $258.10 at $4,000 of take-home pay ($600.00 minus $187.92 minus $116.31 minus $37.67) and $558.10 at $6,000 of take-home pay ($900.00 minus $187.92 minus $116.31 minus $37.67).
What the test leaves out
Parking and tolls. Both are real monthly costs in many cities, but they sit outside this test, so add them to your own total if you pay them.
The car's loss in value. Depreciation is a real cost over 5 years, but it is not a monthly cash payment, so it is not in the 15% line here.
Your own quotes. Insurance, fuel use, and maintenance move with the driver, the car, and the city. Your take-home pay also moves with taxes and deductions. Swap in your own four numbers and the test still works.
How this page differs
The how much car can I afford page works out how much car fits a budget. This page tests a car you already have in mind against the 15% line. Same topic, different question. For your own car, loan, and quote, the calculator is where every input above gets replaced.
Figures and sources
Pete the Planner's ideal budget: total household transportation under 15% of take-home pay, including gas, insurance, and maintenance (petetheplanner.com). Example car figures from the Driveonomics Hyundai Elantra door: 2026 Elantra SE $23,870, 35 mpg, 12,000 miles a year, $4.071 a gallon, the EIA national average, week ending August 31, 2026, $2,255 a year insurance, $452 a year maintenance and repairs, payment $487.73 a month on $24,054 financed at 8% APR over 60 months. Monthly figures are rounded to the cent, then summed, so the table adds exactly.
Educational estimates only, not financial, tax, legal or insurance advice. Every figure on this page is a typical example worked from the inputs stated on the page, not a quote for a specific car, loan, or driver. Your rate, insurance, fuel use, upkeep, and take-home pay will move your total. See Terms.
Calculation transparency
Scope. One rule tested against one named car at two incomes: Pete the Planner ideal budget, total household transportation under 15% of take-home pay, with the Elantra from the site Elantra door as the example car.
Rules and time period. Pete the Planner ideal budget, total household transportation under 15% of take-home pay, including gas, insurance, and maintenance. Example car: 2026 Hyundai Elantra SE $23,870, 35 miles per gallon, 12,000 miles a year, gas at $4.071 a gallon, the EIA national average, week ending August 31, 2026, insurance $2,255 a year, maintenance and repairs $452 a year, payment $487.73 a month on $24,054 financed at 8% APR over 60 months. Monthly figures are rounded to the cent, then summed, so the table adds exactly.
Scope and limitations. Educational estimate only, not financial, tax, legal or insurance advice. Parking and tolls sit outside this test, so add them to your own total if you pay them. The car loss in value is not a monthly cash payment, so it is not in the 15% line here. Insurance, fuel use, and maintenance move with the driver, the car, and the city, and take-home pay moves with taxes and deductions. Swap in your own four numbers and the test still works. Insurance quotes, gas prices, and local rates vary by driver and address. Get a real quote for the same car, coverage, and loan before you decide.
Source links checked November 6, 2026. Figures: Pete the Planner ideal budget, total household transportation under 15% of take-home pay, including gas, insurance, and maintenance; example car figures from the Driveonomics Hyundai Elantra door; EIA national average gas $4.071 a gallon, week ending August 31, 2026; Experian State of the Automotive Finance Market Q2 2026, average rates 6.35% on new cars and 11.19% on used cars, for context against the 8% example rate. No source is named only.
Primary sources: Pete the Planner, bad transportation decisions can derail your budget; EIA Gasoline and Diesel Fuel Update; Experian average car payment; Hyundai Elantra true cost. How the numbers are calculated is written down on the methodology page, and every source is listed on the sources page.
Definitions
Take-home pay. Your pay after taxes and deductions. On this page, $4,000 and $6,000 a month in the two examples.
15% test. Pete the Planner ideal budget: total household transportation under 15% of take-home pay. Multiply your monthly take-home pay by 0.15, and that is your transportation line.
Transportation line. The 15% line for the month. On the example Elantra at $829.63 a month, the line is $600.00 at $4,000 of take-home pay and $900.00 at $6,000.
Payment. The monthly loan payment. On the example car, $487.73 a month on $24,054 financed at 8% APR over 60 months.
Insurance. The insurance line in the test, $2,255 a year, or $187.92 a month, on the example car.
Fuel. The fuel line in the test, 12,000 miles divided by 35 miles per gallon times $4.071, divided by 12, which is $116.31 a month.
Maintenance. Maintenance and repairs, $452 a year, or $37.67 a month, on the example car.
APR. Annual percentage rate, the yearly interest rate on the loan. This example uses 8%. For context, Experian reported average rates of 6.35% on new cars and 11.19% on used cars in the second quarter of 2026.
Questions people actually ask
How much of my income should go to a car?
Under the 15% test, your whole monthly transportation bill, payment, insurance, fuel, and maintenance, should stay under 15% of your take-home pay. On the example Elantra at $829.63 a month, that means $5,530.87 of take-home pay to pass. That is the test, not a verdict: your quotes and your take-home pay move every figure.
What counts inside the 15%?
Payment, insurance, fuel, and maintenance. Parking, tolls, and the car's loss in value sit outside this test. Parking and tolls are real costs, but they are not part of the rule as stated here, and value loss is not a monthly cash payment.
Does the Elantra pass the test at $4,000 of take-home pay?
No. 15% of $4,000 is $600.00, and the car costs $829.63 a month, so it runs $229.63 over the line. At $6,000 of take-home pay the line is $900.00, and the same car passes by $70.37.
What payment fits a $4,000 take-home paycheck?
A payment of $258.10 or less. Start with the $600.00 line, subtract insurance $187.92, fuel $116.31, and maintenance $37.67, and $258.10 is what is left for the payment. At $6,000 of take-home pay the same subtraction leaves $558.10 for the payment.
How is this different from the how much car can I afford page?
That page works out how much car fits a budget. This page tests a car you already have in mind against the 15% line. Same topic, different question, and the calculator is where your own numbers replace the example.
Related: See how much your car payment will be, the number the 15 percent test judges.
Related: See whether to pay cash for a car or finance it.
Related: See whether an 84-month car loan is a good idea when the payment looks too big.
Related: got a raise or a new job? See whether the new money covers a new car.