Loan Calculator
Calculate monthly loan payments, total interest, and a full amortization schedule
What Is a Loan Calculator?
A loan calculator estimates your fixed monthly payment for an installment loan — such as a personal loan, auto loan, or student loan — based on the amount borrowed, the interest rate, and the repayment term. This version also shows total interest, an optional origination fee, and a complete month-by-month amortization schedule so you can see exactly how your balance shrinks over time.
How Loan Payments Work
Each fixed monthly payment is split between interest, calculated on your current remaining balance, and principal, which reduces that balance. Early in the loan, interest makes up a larger share of each payment because the balance is highest. As the balance falls, less of each payment goes to interest and more goes toward principal — the same amortization pattern used by mortgages.
Loan Payment Formula
The standard formula used to calculate a fixed monthly payment is:
M = P × [r(1+r)n] / [(1+r)n − 1]
Where M is the monthly payment, P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments.
Explanation of Every Input
Loan Amount
The total amount you are borrowing, before any origination fee is deducted.
Annual Interest Rate
The yearly rate your lender charges, expressed as a percentage. Even a small difference here compounds significantly over the life of the loan.
Loan Term (Months)
How many months you have to repay the loan. Shorter terms mean higher monthly payments but far less total interest.
Origination Fee
A one-time fee some lenders charge to process the loan, often deducted from the amount you actually receive. It's shown separately here so you can see your true net proceeds and total borrowing cost.
Extra Payments
Extra Monthly Payment and One-Time Extra Payment let you model paying down principal faster than required, which shortens your payoff date and cuts total interest.
Fixed vs. Variable Rate Loans
A fixed-rate loan keeps the same interest rate and payment for the entire term, making budgeting predictable. A variable-rate loan may start lower but can rise over time based on market benchmarks, adding uncertainty to future payments.
Secured vs. Unsecured Loans
Secured loans (like auto loans) are backed by collateral the lender can repossess if you default, which typically means a lower interest rate. Unsecured loans (like most personal loans) have no collateral, so lenders usually charge a higher rate to offset the added risk.
Origination Fees Explained
Origination fees typically range from 1% to 8% of the loan amount depending on the lender and your creditworthiness. If the fee is deducted from your loan proceeds, your net amount received will be lower than the amount you're technically borrowing and repaying.
How to Reduce Loan Interest
- Shop multiple lenders — rates can vary significantly for the same credit profile.
- Choose a shorter term if the higher payment fits your budget.
- Make extra principal payments whenever possible, even small ones.
- Improve your credit score before applying to qualify for a better rate.
- Consider a secured loan option if you have qualifying collateral and a lower rate is available.
Advantages of Using This Calculator
- Instantly compares loan offers without waiting on a lender.
- Reveals the true cost of a loan, including total interest paid.
- Models the impact of extra payments before committing to them.
- Separates origination fees so you can see your real net proceeds.
Limitations
- Results are estimates; actual lender figures may vary slightly.
- Not designed for revolving credit like credit cards.
- Does not include taxes or dealer fees on auto purchases.
Common Mistakes to Avoid
- Comparing loans by monthly payment alone instead of total interest paid.
- Forgetting that a origination fee reduces the amount you actually receive.
- Choosing the longest term available without considering the extra interest cost.
- Not checking whether a loan has a prepayment penalty before paying extra.
Loan Tips
- Get pre-qualified with soft credit checks before formally applying.
- Review your amortization schedule periodically to track payoff progress.
- Set up autopay if it earns an interest rate discount from your lender.
Worked Examples
Personal Loan
Loan Amount: $10,000
Interest Rate: 10%
Term: 36 months
Monthly Payment: $322.67
Total Payment: $11,616.12
Total Interest: $1,616.12
A typical unsecured personal loan used for debt consolidation or a large purchase, repaid over 3 years.
Sarah's Auto Loan
Loan Amount: $25,000
Interest Rate: 7.5%
Term: 60 months
Monthly Payment: $501.00
Total Payment: $30,060.00
Total Interest: $5,060.00
A secured auto loan — the lower rate compared to unsecured loans reflects the vehicle acting as collateral.
Student Loan
Loan Amount: $40,000
Interest Rate: 5.5%
Term: 120 months
Monthly Payment: $434.10
Total Payment: $52,092.00
Total Interest: $12,092.00
A longer 10-year term keeps the monthly payment manageable for a recent graduate, at the cost of more total interest.
Debt Consolidation Loan
Loan Amount: $15,000
Interest Rate: 12%
Term: 48 months
Monthly Payment: $395.05
Total Payment: $18,962.40
Total Interest: $3,962.40
Consolidating higher-rate credit card balances into a single fixed-rate loan can simplify payments and potentially lower overall interest.
Short Term (36 Months)
Loan Amount: $20,000
Interest Rate: 8%
Term: 36 months
Monthly Payment: $626.80
Total Payment: $22,564.80
Total Interest: $2,564.80
Compare this to the 72-month version below on the identical loan amount and rate.
Long Term (72 Months, Same Loan)
Loan Amount: $20,000
Interest Rate: 8%
Term: 72 months
Monthly Payment: $350.60
Total Payment: $25,243.20
Total Interest: $5,243.20
Doubling the term nearly cuts the monthly payment in half, but more than doubles the total interest paid versus the 36-month example above.
Frequently Asked Questions
How accurate is this loan calculator?
This calculator uses the standard amortization formula lenders use to compute principal and interest. Your actual payment may differ slightly due to lender-specific rounding, fees, or day-count conventions for the first payment period.
What types of loans can I use this calculator for?
It works for any fixed-rate installment loan with equal monthly payments, including personal loans, auto loans, student loans, and debt consolidation loans. It is not designed for credit cards or other revolving credit.
Why is the loan term entered in months instead of years?
Personal, auto, and student loans are almost always quoted in months (for example, 36, 48, or 60 months) rather than years, so this calculator matches how lenders typically present loan offers.
How does the interest rate affect my total cost?
Interest is charged on your remaining balance every month for the life of the loan, so even a small rate difference compounds over many payments. A 2% higher rate on the same loan amount and term can add hundreds or thousands of dollars in total interest.
What is an origination fee, and is it included in my monthly payment?
An origination fee is a one-time upfront charge some lenders deduct from your loan proceeds or add to your closing costs. It does not change your monthly principal-and-interest payment, but this calculator shows it separately so you can see your true total cost and net amount received.
Should I choose a shorter or longer loan term?
A shorter term means a higher monthly payment but significantly less total interest paid. A longer term lowers your monthly payment for better cash flow, but increases the total interest over the life of the loan. Compare both in the amortization schedule below.
How much can extra payments save me?
Every extra dollar applied to principal reduces the balance that future interest is calculated on, which can shorten your payoff date and meaningfully cut total interest. Use the Extra Monthly Payment and One-Time Extra Payment fields in Advanced Options to model this.
What credit score do I need for a good interest rate?
Lenders generally reserve their lowest rates for borrowers with strong credit scores (typically 700+), while lower scores usually mean higher rates or a co-signer requirement. Enter the actual rate quoted to you for the most accurate estimate.
Can I pay off my loan early without a penalty?
Many personal and auto loans allow early payoff without a fee, but some loans do carry prepayment penalties, so it is worth checking your loan agreement before making large extra payments.
What is the difference between a secured and unsecured loan?
A secured loan (like an auto loan) is backed by collateral the lender can repossess if you default, which usually means a lower interest rate. An unsecured loan (like most personal loans) has no collateral backing it, so it typically carries a higher interest rate to offset the lender's added risk.
How exactly is my monthly payment calculated?
This calculator uses the standard fixed-payment amortization formula, which spreads your loan amount and interest evenly across every scheduled payment so that the balance reaches zero exactly at the end of the term (before any extra payments you add).
Does this calculator include taxes or other fees?
No. This tool focuses on principal and interest, plus an optional origination fee. Sales tax on vehicle purchases, documentation fees, and similar charges vary by lender and location and should be confirmed directly with your lender or dealer.
What happens if I miss a loan payment?
Missing a payment typically triggers late fees, can hurt your credit score, and — for secured loans — may eventually put your collateral at risk of repossession. Contact your lender proactively if you think you will miss a payment.
Should I choose a fixed or variable interest rate?
A fixed rate keeps your payment the same for the entire term, which makes budgeting predictable. A variable rate can start lower but may rise over time based on market conditions, which adds uncertainty to your future payments.
How can I lower my monthly payment?
The main levers are borrowing less, choosing a longer term, or qualifying for a lower interest rate by improving your credit or shopping multiple lenders. Keep in mind that a longer term usually increases total interest even though it lowers the monthly payment.
Conclusion
Whether you're financing a car, consolidating debt, or covering education costs, understanding how amount, rate, term, and extra payments interact helps you borrow smarter. Use this calculator to compare offers side by side and see exactly how much a loan will really cost you before you sign anything.