How to Use This Loan Calculator
Our free loan calculator helps you estimate your monthly payment and total cost for any fixed-rate loan — whether it's an auto loan, personal loan, student loan, or any other type of installment loan.
Steps:
- Enter the total loan amount (the amount you want to borrow)
- Enter the annual interest rate (as a percentage)
- Select the loan term in years (1 to 30 years)
- View your monthly payment, total interest, and amortization schedule instantly
How Loan Payments Are Calculated
For a fixed-rate loan, your monthly payment is calculated using a standard amortization formula. This formula ensures that every monthly payment is the same amount, with the portion going to interest decreasing and the portion going to principal increasing over time.
The standard loan payment formula:
M = P × [r(1 + r)^n] ÷ [(1 + r)^n – 1]Where:
- M = monthly payment
- P = principal (loan amount)
- r = monthly interest rate (annual rate ÷ 12)
- n = total number of payments (years × 12)
Example: For a $25,000 loan at 6.5% interest over 5 years:
P = $25,000, r = 0.065 ÷ 12 = 0.005417, n = 5 × 12 = 60.
M = $489.15/month | Total paid = $29,349.15 | Total interest = $4,349.15
Understanding Amortization
Amortization is the process of spreading a loan into a series of fixed payments over time. Each payment consists of two parts:
- Principal: The portion that reduces your outstanding loan balance
- Interest: The cost of borrowing, calculated on the remaining balance
In the early months of a loan, most of your payment goes toward interest. As the balance decreases, more of each payment is applied to principal. This is why the amortization table shows interest payments shrinking and principal payments growing each year.
| Year | Principal Paid | Interest Paid | Remaining Balance |
|---|---|---|---|
| Year 1 | $4,286 | $1,584 | $20,714 |
| Year 2 | $4,571 | $1,299 | $16,143 |
| Year 3 | $4,876 | $994 | $11,267 |
| Year 4 | $5,202 | $668 | $6,065 |
| Year 5 | $5,549 | $321 | $0 |
Example above: $25,000 loan at 6.5% over 5 years. Monthly payment: $489.15.
Types of Loans
This calculator works for any fixed-rate installment loan. Common types include:
| Loan Type | Typical Amount | Typical Term | Typical Rate |
|---|---|---|---|
| Personal loan | $1,000 – $50,000 | 1 – 7 years | 6% – 36% |
| Auto loan | $5,000 – $60,000 | 3 – 7 years | 4% – 12% |
| Student loan | $5,000 – $100,000+ | 10 – 25 years | 3% – 8% |
| Home equity loan | $10,000 – $500,000 | 5 – 30 years | 5% – 12% |
| Small business loan | $5,000 – $500,000 | 1 – 25 years | 6% – 30% |
How Interest Rates Affect Your Loan
Even a small difference in interest rate can have a significant impact on your total cost. Here's how rate changes affect a $25,000 loan over 5 years:
| Interest Rate | Monthly Payment | Total Interest | Total Paid |
|---|---|---|---|
| 4.0% | $460.41 | $2,624.70 | $27,624.70 |
| 6.5% | $489.15 | $4,349.15 | $29,349.15 |
| 9.0% | $518.92 | $6,135.20 | $31,135.20 |
| 12.0% | $556.11 | $8,366.53 | $33,366.53 |
A rate increase from 4% to 12% nearly doubles the total interest paid — from $2,625 to $8,367 on the same $25,000 loan. Shopping for the best rate can save you thousands.
Tips for Saving on Loan Costs
- Improve your credit score before applying — borrowers with excellent credit (740+) get the lowest rates
- Choose a shorter loan term — you'll pay more monthly but significantly less in total interest
- Make extra payments — even small additional payments toward principal can reduce total interest and shorten your loan
- Shop multiple lenders — banks, credit unions, and online lenders often offer different rates
- Consider a secured loan — using collateral can get you a lower rate than an unsecured personal loan
- Refinance if rates drop — refinancing to a lower rate can save money, but factor in closing costs
- Avoid fees — watch for origination fees, prepayment penalties, and late payment fees that add to the total cost
Frequently Asked Questions
How is the monthly payment calculated?
The monthly payment is calculated using the standard amortization formula: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate, and n is the total number of payments. This produces equal monthly payments over the life of the loan.
Does this calculator work for mortgages?
This calculator uses the same formula as a mortgage calculator, but it doesn't include property taxes, homeowners insurance, or PMI. For a full mortgage estimate, use our dedicated Mortgage Calculator.
What is amortization?
Amortization is the process of paying off a loan through scheduled, equal payments. Each payment covers both interest (calculated on the remaining balance) and principal (reducing the balance). Over time, the interest portion decreases and the principal portion increases.
Can I pay off my loan early?
Most loans allow early payoff, but some include prepayment penalties. Making extra payments toward principal reduces your total interest and shortens the loan term. Check your loan agreement for any prepayment penalties before making large additional payments.
How does loan term affect total cost?
A shorter loan term means higher monthly payments but less total interest paid. A longer term lowers monthly payments but costs more over time. For example, a $25,000 loan at 6.5% costs $4,349 in interest over 5 years but $9,036 over 10 years — more than double the interest.
What is the difference between APR and interest rate?
The interest rate is the cost of borrowing the principal amount. The APR (Annual Percentage Rate) includes the interest rate plus other costs like origination fees and closing costs. APR gives a more complete picture of the total loan cost. When comparing loans, always compare APR rather than just the interest rate.
This calculator provides estimates for informational purposes only. Actual loan terms, payments, and interest may vary. Consult with a financial advisor or lender for personalized advice.