Loan Calculator
Calculate estimated monthly payments and total interest for mortgages, auto loans, or personal loans.
How Loan Payments are Calculated
This calculator uses the standard amortization formula to determine fixed monthly payments over the life of a loan. This applies to mortgages, auto loans, personal loans, and student loans.
The Formula:
M = P [ r(1 + r)^n ] / [ (1 + r)^n - 1 ]
- M: Total monthly payment
- P: Principal loan amount
- r: Periodic interest rate (annual rate divided by 12)
- n: Total number of payments (years multiplied by 12)
Understanding the Costs
When you take out a loan, the total cost involves more than just the amount you borrow. The interest rate and loan term significantly impact how much you ultimately pay.
1. The Loan Term Impact
A longer loan term (like a 30-year vs. 15-year mortgage) spreads your payments out over more time, resulting in a lower monthly payment. However, because the principal is carried longer, you accrue more total interest. A shorter term means higher monthly payments, but substantial interest savings.
2. Amortization Mechanics
During the early years of an amortized loan, a large portion of your monthly payment goes toward interest, while only a small fraction reduces the principal balance. As you progress through the loan term, this ratio flips, and more of your payment starts attacking the principal.
3. Hidden Costs (Not Included in Estimate)
Remember that this calculator computes principal and interest only. Real-world loans often include extra fees:
- Mortgages: Property taxes, homeowner's insurance, HOA fees, and PMI (if down payment is under 20%).
- Auto Loans: Sales tax, title fees, and dealer documentation fees.
- Personal Loans: Origination fees or prepayment penalties.
Frequently Asked Questions
How do you calculate a monthly loan payment?
Monthly loan payments are calculated using an amortization formula that takes the principal amount, multiplies it by the periodic interest rate, and divides that by one minus (1 plus the periodic interest rate) to the negative power of the total number of payments.
What is amortization?
Amortization is the process of spreading out a loan into a series of fixed payments over time. Early payments primarily cover interest, while later payments pay down more of the principal.
Does a longer loan term mean smaller payments?
Yes, extending the loan term reduces your monthly payment because you are spreading the cost over a longer period. However, a longer term also means you will pay significantly more in total interest over the life of the loan.
Can I save money by making extra payments?
Yes. Any extra payments made toward the principal reduce the remaining balance on which future interest is calculated. This can help you pay off the loan faster and save a substantial amount on interest.
Why is my actual payment higher than the calculator estimate?
Calculators typically estimate the principal and interest portion of your loan. Actual payments, especially for mortgages or auto loans, may include additional costs like property taxes, homeowner's insurance, PMI (Private Mortgage Insurance), or dealer fees.