When to use this calculator
Work backwards from a payment you choose to explore how loan duration and interest rates change the amount financed.
Explore the loan & repayment calculators for other questions in this topic. For a related calculation, use the Loan Balance Calculator: Estimate outstanding principal after a chosen number of regular loan payments.
PUTTING IT INTO PRACTICE
Loan Affordability: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Monthly payment budget | 100 |
| Nominal annual rate (%) | 0 |
| Term (years) | 1 |
| Result | 1,200 currency units |
- Check the input labels and enter the example values above.
- Apply the relationship: Principal = payment × (1 − (1+m)^(-12y))/m.
- The result is 1,200 currency units, rounded for display.
How to interpret your result
A mathematical payment limit, not a lending approval or assessment of your full household budget.
Use a fixed-rate amortising model for loans repaid by equal monthly instalments. An interest-only payment leaves the principal outstanding. Fees and contractual APR calculations require more than the interest rate alone.
Frequently asked questions
Does a lower monthly payment mean a cheaper loan?
Not necessarily. Extending the term can lower payments while increasing total interest. Compare both monthly affordability and overall cost.
When is the loan affordability calculator useful?
Work backwards from a payment you choose to explore how loan duration and interest rates change the amount financed.
How do I use the loan affordability calculator?
Enter monthly payment budget, nominal annual rate (%), term (years). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Principal = payment × (1 − (1+m)^(-12y))/m.
What should I check before using the result?
A mathematical payment limit, not a lending approval or assessment of your full household budget.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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