Loan Interest Calculator
Know your total interest, monthly payment, and full repayment amount before you borrow.
Total borrowed amount
APR (fixed rate)
How long to repay
| Period | Interest Paid | Remaining Balance |
|---|
Based on standard amortization (equal monthly payments).
How Loan Interest Calculation Works
This calculator uses the standard amortization formula for fixed-rate loans. The monthly payment includes both principal and interest. Over time, more of your payment goes toward principal. The total interest you pay depends on the loan amount, interest rate, and loan term. The formula used is the standard loan payment formula:
Total interest = (Monthly Payment × Total Payments) – Loan Amount. This gives you the exact cost of borrowing. For example, a $25,000 loan at 7.5% for 5 years costs about $5,036 in total interest. Your monthly payment would be around $500. Use this tool before signing any loan agreement.
🚗 Auto Loan Example
Car price: $32,000, down payment $7,000 → loan $25,000. Rate 6.9% for 60 months: monthly payment $494, total interest $4,640.
🏠 Personal Loan Comparison
Borrow $10,000 at 12% for 3 years: monthly $332, total interest $1,955. For 5 years: monthly $222, but total interest $3,322. Longer term means lower payment but higher total interest.
💡 Tip box: Reduce total interest fast. Paying extra toward principal each month or making biweekly payments can cut years off your loan and save hundreds or thousands in interest. Even $50 extra monthly makes a big difference.
Table of Truth: Loan Interest Examples
Use this table to quickly estimate loan costs without doing math. All examples assume fixed rate, standard amortization.
| Loan Amount | Rate | Term | Monthly Payment | Total Interest |
|---|---|---|---|---|
| $10,000 | 5.0% | 3 years | $299.71 | $789.56 |
| $15,000 | 6.5% | 5 years | $293.50 | $2,610.00 |
| $20,000 | 8.0% | 4 years | $488.26 | $3,436.48 |
| $50,000 | 4.5% | 10 years | $518.21 | $12,185.20 |
| $7,500 | 10% | 2 years | $346.05 | $805.20 |
Common Mistakes People Make With Loan Interest
Frequently Asked Questions (People Also Ask)
What is the difference between simple interest and compound interest on loans?
Simple interest is calculated only on the principal. Compound interest is calculated on principal plus accumulated interest. Most personal and auto loans use compound interest (amortized) where interest accrues on the remaining balance. This calculator uses standard compound amortization.
How can I lower my total loan interest?
Make extra principal payments, choose a shorter loan term, improve your credit score to qualify for lower rates, or refinance when rates drop. Even one extra payment per year reduces interest significantly.
Does loan interest percentage include fees?
No. This calculator shows pure interest cost. Origination fees, closing costs, or prepayment penalties are not included. For full loan cost, ask your lender for the APR (Annual Percentage Rate).
What is a good interest rate for a personal loan?
In 2025, good personal loan rates range from 6% to 12% for borrowers with good credit. Rates above 15% are expensive. Use this calculator to see total interest before applying.
Can I use this for mortgage calculations?
Yes, this works for any fixed-rate loan including mortgages. For a 30-year mortgage, enter the loan amount, rate, and 30 years. Note that property taxes and insurance are not included here.
What happens if I pay off my loan early?
Paying early reduces total interest because interest stops accruing on the paid principal. Check for prepayment penalties in your contract. Most personal and auto loans have no penalties.
📌 Why SabiCalculator? No signups. No email. No tracking. Just fast, accurate loan math when you need it. Built for real people who want straight answers before borrowing money.
© SabiCalculator — Loan Interest Calculator. All calculations are estimates. Actual loan terms may vary based on lender policies, credit score, and fees. Always consult a financial advisor for major decisions.
