StraightToolsLoan Calculator
Estimate a fixed-rate loan payment and total interest.
Fixed-payment loans
The standard amortization formula is used. Fees and variable rates are not included.
When to use this tool
Use this tool to compare fixed-payment loans such as personal loans, auto loans, or other installment debt. Changing the rate or term makes the tradeoff between monthly affordability and total interest easy to see.
How the result is calculated
The payment is calculated with the standard amortization formula for a fixed interest rate and equal monthly payments. Each payment contains both interest and principal, with the interest share generally declining over time.
Worked example
For a $25,000 loan, compare a five-year term with a shorter three-year term. The shorter term usually costs more each month but can save a meaningful amount of total interest.
What to keep in mind
Origination fees, prepayment rules, taxes, insurance, variable rates, and lender-specific compounding can change the true cost. Always compare the lender’s APR and disclosure documents before borrowing.
About our calculations
StraightTools is designed to show the method behind the answer, not just the result. Inputs are handled in your browser for this tool. For important financial, legal, medical, tax, safety, or contractual decisions, verify the result with an appropriate authoritative source or qualified professional.