Loan Calculator | Payment & Amortization

Quick Start Guide

  1. Enter loan amount: The total amount you're borrowing.
  2. Set interest rate: The annual percentage rate (APR) of the loan.
  3. Choose loan term: Select years or months for the repayment period.
  4. Add extra payments (optional): See how additional payments reduce interest and payoff time.
  5. View your results: Monthly payment, total interest, and total cost update instantly.
  6. Explore the amortization schedule: See a month-by-month breakdown of principal vs. interest.
  7. Compare loan options: Use comparison mode to evaluate multiple offers side by side.
  8. Export your results: Save your analysis as JSON, CSV or PDF.

Understanding Loan Payments

Why your payment stays flat but the split changes

A fixed-rate loan uses amortization: the total monthly payment never changes, but early payments are mostly interest and later payments are mostly principal. That is why paying off a loan early saves more interest the sooner you start — you are skipping interest on a balance that would otherwise compound for years.

What "extra payment" actually does

The extra payment field adds a recurring amount to every monthly payment for the life of the loan — it is not a one-time lump sum. That recurring extra goes straight to principal, which is why even a modest extra payment compounds into a meaningfully shorter payoff term and lower total interest.

Simple, Refinance, and Comparison modes

Simple mode answers "what will my payment be." Refinance mode answers a different question — "is switching loans worth it" — by comparing your current loan against a new one and showing the breakeven point once closing costs are factored in. Comparison mode lets you line up up to three loan offers side by side on the same terms.

Reading the amortization schedule

The schedule breaks every payment into principal and interest and tracks the running balance. It is the fastest way to see exactly when a loan crosses from "mostly interest" to "mostly principal" — usually somewhere past the halfway mark on longer terms.

What this calculator does not cover

This is a general installment loan calculator — for a home purchase with PMI and property tax/insurance, use the Mortgage Calculator; for auto financing with trade-in and negative equity, use the Car Loan Calculator. Neither sales tax nor origination fees beyond the optional fees field are modeled automatically.

Features

Loan Comparison: Compare up to 3 different loan options side-by-side. See monthly payments, total interest, and payoff dates for each option before you commit.

Refinance Analysis: Compare your current loan with a new loan option. See breakeven point, total savings, and whether refinancing makes financial sense.

Loan Optimization: Get recommendations on how to optimize your loan. See how extra payments, different terms, or interest rates affect your total cost.

Amortization Schedule: View a detailed month-by-month breakdown of your loan payments. See how much goes to principal vs interest over the life of the loan.

Payment Charts: Visualize your payment breakdown with interactive charts. See principal vs interest allocation over time.

Export Data: Export your loan calculations to JSON, CSV, or PDF format for record-keeping or sharing with lenders.

Common Use Cases

Personal Loan Planning: compare different loan terms (3, 5, 7 years) to find the best monthly payment, see total interest cost for each option, and calculate how extra payments reduce payoff time.

Auto Loan Comparison: use comparison mode to evaluate 2-3 loan offers side-by-side, compare monthly payments, total interest, and payoff dates, and factor in different interest rates and terms.

Refinancing Analysis: enter current loan details and new loan terms, see the breakeven point when refinancing pays off, and calculate total savings over the loan lifetime.

Extra Payment Strategy: see how $50, $100, or $200/month extra payments affect total cost, calculate months/years saved on the loan term, and view the updated amortization schedule with extra payments.

Frequently Asked Questions

Monthly loan payments are calculated using the standard amortization formula: M = P * [r(1+r)^n] / [(1+r)^n – 1], where M is monthly payment, P is principal, r is monthly interest rate, and n is number of payments. Our calculator handles this automatically — just enter loan amount, interest rate, and term.
Extra payments directly reduce the principal balance, which saves interest and shortens the loan term. For example, adding $50/month to a $20,000 loan at 7.5% can save thousands in interest and pay off the loan months or years earlier. Our calculator shows exact savings and new payoff date.
Refinancing makes sense if the new loan's interest rate is significantly lower, you can shorten the term, or you need to change loan terms. Use our refinance mode to compare your current loan with a new option. The breakeven analysis shows when refinancing pays off after accounting for closing costs.
Use our comparison mode to evaluate up to 3 loan options side-by-side. Compare monthly payments, total interest costs, and payoff dates. Look beyond just the interest rate — consider total cost, monthly payment affordability, and loan term. The calculator highlights which loan saves the most money.
An amortization schedule shows how each payment is split between principal and interest over the life of the loan. Early payments are mostly interest, while later payments are mostly principal. Our calculator generates a detailed month-by-month schedule showing payment breakdown, remaining balance, and cumulative interest paid.

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