Loan Calculator
Calculate monthly payments, total interest, and view a full amortization schedule. Supports mortgage, auto, and personal loans.
Default: $250,000 mortgage at 6.5% for 30 years
Amortization Schedule
| Period | Payment | Principal | Interest | Remaining Balance |
|---|
Understanding Loan Amortization
A loan amortization schedule breaks down every payment over the life of a loan, showing exactly how much goes toward principal and how much goes toward interest. For most fixed-rate installment loans — mortgages, auto loans, student loans, and personal loans — each monthly payment is the same dollar amount, but the composition of that payment shifts dramatically over time. In the early years, interest dominates; by the final years, nearly every dollar goes to principal.
How Amortization Works
Amortization uses a standard mathematical formula to calculate the fixed monthly payment required to pay off a loan over a given term at a given interest rate. The formula is:
M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1]
Where M is the monthly payment, P is the principal (loan amount), r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments (years × 12). This formula ensures that by the final payment, the remaining balance reaches exactly zero — hence the term "fully amortizing."
Principal vs. Interest Over Time
In a typical 30-year mortgage at 6.5%, your first monthly payment might be 85% interest and only 15% principal. By year 15, the split approaches 50/50. In the final year, over 95% of each payment chips away at the remaining principal. This front-loaded interest structure is why making extra principal payments early in the loan term has an outsized impact — every extra dollar reduces the balance on which future interest is calculated, creating a compounding savings effect over the remaining term.
Different Types of Loans
- Fixed-Rate Mortgage: The most common home loan. Interest rate stays constant for the entire term (typically 15 or 30 years). Predictable payments make budgeting straightforward. The tradeoff: initial rates may be slightly higher than adjustable-rate alternatives.
- Adjustable-Rate Mortgage (ARM): Starts with a lower "teaser" rate that adjusts periodically based on market indexes. Common variants: 5/1 ARM (fixed for 5 years, then adjusts annually). Riskier for borrowers who plan to stay long-term.
- Auto Loans: Typically 3–7 year terms with fixed rates. Depreciation is a key consideration — you don't want to owe more than the car is worth (being "underwater"). Shorter terms minimize total interest paid.
- Personal Loans: Unsecured loans with terms from 1–7 years. Rates vary widely based on credit score. Often used for debt consolidation, home improvements, or major purchases.
- Student Loans: Federal loans offer income-driven repayment plans and potential forgiveness. Private student loans function more like personal loans with fixed or variable rates.
Factors That Affect Your Loan
Several variables determine your total borrowing cost:
- Credit Score: The single biggest factor in determining your interest rate. A difference of just 1% on a $250,000 mortgage adds over $50,000 in extra interest over 30 years.
- Down Payment: A larger down payment reduces the loan amount (and thus total interest) and may eliminate Private Mortgage Insurance (PMI) on conventional loans.
- Loan Term: A 15-year mortgage typically offers a lower rate and dramatically less total interest — but the monthly payment is higher. Use this calculator to compare scenarios side by side.
- Extra Payments: Even $100 extra per month can shave years off a mortgage and save tens of thousands in interest.
Strategies to Save on Interest
Making biweekly payments instead of monthly (26 half-payments = 13 full payments per year) effectively adds one extra payment annually, which can cut a 30-year mortgage down to about 25 years. Refinancing when rates drop can lock in lower monthly costs, though closing costs must be weighed against the savings. Rounding up your payment to the nearest $50 or $100 is the simplest habit — it requires no commitment and still accelerates your payoff. Use our calculator above to model different scenarios and see exactly how each strategy affects your bottom line.
💡 Pro Tips for Loan Calculations
- The "Rule of 72" quick check: Divide 72 by your interest rate to estimate how many years it takes for your debt to double if you only pay minimums. At 6.5%, your balance doubles in ~11 years without principal payments — a gut check for why you want to pay down faster.
- Compare total cost, not just monthly payment: A $250k loan at 6.5% for 30 years costs $568,861 total. The same loan at 15 years costs $392,069 — saving over $176,000 in interest. Our calculator makes this comparison trivial: just change the term and hit Calculate.
- Add "ghost payments" to your budget: When refinancing from 6.5% to 5%, your required payment drops but you keep paying the old amount. The extra goes directly to principal, slashing years off the loan without lifestyle impact.
- Compare scenarios side by side: Open two browser tabs with this calculator and run different terms — 15-year vs 30-year, or 6% vs 7% rate. The total interest difference becomes immediately obvious and often justifies refinancing or making extra payments now rather than later.
Frequently Asked Questions
How do I calculate my monthly loan payment?
The formula is M = P × [r(1+r)^n] / [(1+r)^n − 1] where P is your loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Our calculator does this instantly — just enter your loan amount, rate, and term.
What's the difference between APR and interest rate?
The interest rate is the cost of borrowing the principal. APR (Annual Percentage Rate) includes the interest rate plus lender fees, points, and closing costs — giving a truer picture of total borrowing cost. Always compare APRs when shopping loans, not just the advertised rate.
Can I use this calculator for auto loans or personal loans?
Yes — the math is the same for any fixed-rate installment loan. Enter the vehicle price as the loan amount, your quoted rate, and the term in years (3-7 for auto, 1-7 for personal). The amortization schedule works identically whether it's a house or a car.
What happens if I make extra payments?
Extra payments go directly to principal, reducing the balance on which future interest is calculated. This creates a compounding effect: $100 extra per month on a $250k 6.5% 30-year mortgage saves roughly $49,000 in interest and pays off the loan ~4.5 years early. Try different extra payment amounts in our calculator by reducing the loan amount to simulate the effect.
What is biweekly payment and how much does it save?
Biweekly payment means paying half your monthly amount every two weeks. Since there are 52 weeks in a year, you make 26 half-payments — equivalent to 13 full monthly payments instead of 12. That one extra payment per year compounds significantly: on a $250k 30-year mortgage at 6.5%, biweekly payments save roughly $53,000 in interest and pay off the loan 4-5 years early. The best part? It barely feels different from monthly payments, but the math works in your favor automatically.
Does this calculator include property taxes and insurance?
No — this calculator focuses on the loan itself (principal + interest), which is the portion you can control. Property taxes, homeowners insurance, and PMI vary by location and lender. To estimate your full monthly housing cost, calculate your P&I here, then add your local tax rate (~1-2% of home value annually), insurance (~$100-200/month), and PMI if your down payment is under 20%. For auto loans, add registration and insurance separately.
Why Use Our Loan Calculator?
Our calculator goes beyond simple monthly payment estimates. The detailed amortization table shows you exactly how each payment is allocated over the first year, plus yearly summaries so you can track your progress. The CSS-only pie chart gives you an instant visual of the principal-to-interest ratio. All calculations happen instantly in your browser with no page reloads. Whether you're shopping for a mortgage, comparing auto loan offers, or planning to consolidate debt, this tool gives you the clarity you need to make informed financial decisions. Best of all — it's completely free, requires no sign-up, and your financial data never leaves your device.