Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Reverse-solving from a payment limit to a loan amount answers a narrower question than whether a loan is truly affordable. It tells you the borrowing ceiling a specific payment supports at a specific rate and term, and says nothing about taxes, insurance or other debts that also draw on the same monthly budget.
Before you rely on it
What to check
Subtract other recurring debt obligations from your available payment budget before using the remaining amount as the input here, rather than using gross available cash.
The common error
Where people go wrong with loan affordability calculator
Treating the maximum affordable loan amount as a target to borrow up to. The ceiling reflects what a payment supports mathematically, not what leaves comfortable room for the rest of a real budget.
Sensitivity evidence
How annual interest rate changes the affordable loan amount
| Annual interest rate | Affordable loan amount | Total payments |
|---|---|---|
| 5.5% | $26,176 | $30,000 |
| 6.5% | $25,554 | $30,000 |
| 7.5%worked example | $24,953 | $30,000 |
| 8.5% | $24,371 | $30,000 |
| 9.5% | $23,807 | $30,000 |
Every input, tested
Which input moves the affordable loan amount most
| Input | Tested from | To | Affordable loan amount at each end | Swing |
|---|---|---|---|---|
| Loan term | 4.0 years | 6.0 years | $20,679 to $28,918 | $8,239 (33%) |
| Maximum monthly payment | $450 | $550 | $22,457 to $27,448 | $4,991 (20%) |
| Annual interest rate | 6.5% | 8.5% | $25,554 to $24,371 | $1,184 (4.7%) |
Two variables at once
Affordable loan amount by annual interest rate and maximum monthly payment
| Annual interest rate \ Maximum monthly payment | $400 | $500 | $600 |
|---|---|---|---|
| 5.5% | $20,941 | $26,176 | $31,412 |
| 6.5% | $20,443 | $25,554 | $30,665 |
| 7.5% | $19,962 | $24,953 | $29,943 |
| 8.5% | $19,496 | $24,371 | $29,245 |
| 9.5% | $19,046 | $23,807 | $28,569 |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Maximum monthly payment | $500 |
| Annual interest rate | 7.5% |
| Loan term | 5.0 years |
| Affordable loan amount | $24,953 |
| Total payments | $30,000 |
Where the inputs come from
Start from a payment limit you can defend, not the largest payment a lender would approve. Take monthly take-home pay, subtract rent or housing, insurance, food, existing debt payments and savings, and use what remains, minus a cushion. For the rate, use a quote for your credit tier if you have one; a rate from an advertisement is usually the best-tier rate. Match the term to the loan you are shopping for, since the affordable principal changes sharply with it.
When the result stops applying
The figure ignores fees, insurance, sales tax and any add-ons financed with the loan, all of which use up part of the principal. It also assumes the payment stays fixed. A variable rate, a balloon or a payment that rises after an introductory period breaks the calculation, and lenders' own affordability tests use debt-to-income ratios that may allow more than is comfortable.
What to compare it with
Pair this with a real budget rather than a rule of thumb. List the fixed payments you already carry, since lenders count them against you, and note which of them end within the loan's term, because a car loan that finishes in two years frees room later. If you are shopping for a car or a home, run the purchase price through the payment calculator afterwards to see what the ceiling buys. When the result is smaller than expected, a co-borrower or a larger down payment usually helps more than a longer term.
People also ask
Frequently asked questions
Should I borrow up to the amount shown?
Not automatically. The amount shown is the most that a payment limit supports; it says nothing about whether the purchase is worth it. Many buyers borrow well below the ceiling to leave room for repairs and changes in income.
Why does a small change in term move the affordable amount so much?
Payment is spread over more months, so the same monthly figure supports a larger balance. Going from 4 to 6 years at the same payment and a 7.5% rate raises the borrowable amount by about 40%.
What if I add a down payment?
The down payment adds to the loan amount. Buying power equals this calculator's principal plus the cash you put down, before taxes and fees.