About the Loan Calculator

Before you sign a loan agreement, you should know exactly what it will cost you — not just the interest rate, but the total amount paid over the life of the loan, the monthly payment, and how extra payments would accelerate payoff. Our Loan Calculator gives you all of this in seconds.

It works for personal loans, student loans, auto loans, and any other installment loan. Enter the loan amount, annual interest rate, and term, and you get a full payment breakdown with an optional amortization schedule showing how each payment is split between interest and principal.

How It Works

The calculator uses the standard installment loan formula to compute the fixed monthly payment that fully amortizes the loan over the specified term. It then calculates total payments, total interest, and generates an amortization table showing the principal and interest components of each payment.

Formula / Key Reference

Monthly Payment = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
Total Paid = Monthly Payment × n
Total Interest = Total Paid − P
Where: P = loan amount, r = monthly interest rate (annual rate ÷ 12), n = number of months

Real-World Example

Personal loan: $15,000 at 10% annual interest over 4 years

Monthly payment = $15,000 × [0.00833 × (1.00833)^48] / [(1.00833)^48 − 1]
= $15,000 × 0.02536 = $380.44/month
Total paid: $380.44 × 48 = $18,261.12
Total interest: $18,261.12 − $15,000 = $3,261.12

What if you paid an extra $100/month ($480.44 total)?

You'd pay off the loan in approximately 38 months instead of 48

Total interest drops from $3,261 to about $2,529 — saving $732 and 10 months.

Common Uses

  • Comparing loan offers from different lenders before applying
  • Understanding total cost of borrowing (not just the monthly payment)
  • Calculating the impact of extra payments on loan payoff timeline
  • Budgeting for a new loan by confirming payment fits your income
  • Refinancing analysis: comparing new vs. existing loan terms

Frequently Asked Questions

What is the difference between APR and interest rate? ▼
The interest rate is the cost of borrowing the principal, expressed as a percentage. APR (Annual Percentage Rate) includes the interest rate plus any fees (origination fees, closing costs, points), making it a more complete measure of the true annual cost of a loan. Always compare APR when shopping for loans.
Should I choose a shorter or longer loan term? ▼
A shorter term means higher monthly payments but dramatically less total interest paid. A longer term means lower payments but significantly more interest over time. Choose based on your monthly budget, but be aware of the true cost. Our calculator shows the total interest for any term combination instantly.
Can I pay off my loan early? ▼
Most personal loans and auto loans allow early payoff. Making one extra payment per year can cut years off a long loan and save significant interest. Always check for prepayment penalties before making extra payments — some lenders charge a fee for early payoff, though this is becoming less common.
What credit score do I need for a good loan rate? ▼
Generally, a FICO score above 720 qualifies for the best rates. Scores from 660–719 typically qualify for good rates. Below 620, you may only qualify for subprime loans with significantly higher rates. Improving your credit score before applying for a large loan can save thousands of dollars.