📉 Amortization Calculator

Calculate your loan payment and full amortization schedule, then add extra payments to see your real payoff date and interest saved.

📊 Loan Details
$
%
Typical: 6.5–7.5% (30-yr loan)
Extra Payments
$
$
📈 Results
Monthly Payment
principal & interest
Total Interest
over full term
Total Cost
principal + interest
Payoff Date
estimated
Principal vs Interest
Year-wise Principal vs Interest
Amortization Schedule (First 12 Payments)
#DatePaymentExtraPrincipalInterestBalance
📉

Enter Loan Details

Fill in the loan amount, interest rate, and term, then click Calculate to see your full amortization schedule.

Guide

What Is the Amortization Calculator?

Last updated: July 2026 · Reviewed by the NeftCal editorial team

An amortization calculator shows exactly how a fixed-payment loan is paid off over time — how much of each payment goes toward interest versus principal, and how the outstanding balance shrinks with every payment until it reaches zero. This calculator works for any amortized loan: mortgages, auto loans, personal loans, and student loans all follow the same reducing-balance structure. As an amortization schedule with extra payments built in, it also lets you model extra monthly, yearly, or one-time payments to see how much faster you could pay off the loan and how much interest you'd save.

Enter the loan amount, annual interest rate, and loan term, and the calculator computes your fixed monthly payment using the standard amortization formula. It then walks the loan month by month from your chosen start date, applying any extra payments directly to principal, to produce a full amortization schedule showing the payment, interest, principal, and remaining balance for every period. The result also includes a payoff date, total interest paid, and — when extra payments are added — the interest saved and time saved compared to the standard schedule.

Who Should Use This Calculator

This tool is for anyone who wants to see the real mechanics behind a loan payment — homeowners comparing loan terms, borrowers deciding whether an extra monthly payment is worth budgeting for, and anyone planning to apply a bonus or tax refund toward a loan and wanting to know exactly how much time and interest it saves. It's equally useful for a single "what if" check and for generating a full payment-by-payment table to keep for your records.

Why It Matters for Financial Planning

Loan payments are front-loaded with interest: early in the loan, most of each payment covers interest on the large outstanding balance, and only a small portion reduces principal. Seeing the full schedule makes this visible, and shows why even modest extra payments made early in a loan can meaningfully cut both the total interest paid and the time it takes to become debt-free. Understanding this dynamic is one of the most practical financial-planning skills a borrower can have, since it turns an abstract interest rate into a concrete payoff-date and interest-saved number.

Common Scenarios

  • Generating a full amortization schedule to keep alongside your mortgage or auto loan paperwork
  • Testing how a $100–$300 extra monthly payment changes your payoff date and total interest
  • Modeling a lump-sum bonus or tax refund as a one-time payment on a specific date
  • Comparing a 15-year vs. 20-year term's principal-vs-interest split year by year
  • Checking exactly how much of your next payment is interest versus principal

Tips for Accurate Results

  • Use your loan's actual start date so the payoff date and one-time payment months line up with your real payment schedule
  • Try adding a modest Extra Monthly Pay to see how much interest even small extra payments can save over the life of a long-term loan
  • Use Extra One-time Pay for windfalls like a bonus or tax refund, entered on the date you'd actually make the payment
  • Compare different loan terms side by side to see the trade-off between a lower monthly payment and lower total interest
  • Extra payments only help if your lender applies them to principal with no prepayment penalty — check your loan agreement
Formula

How Your Amortization Schedule Is Calculated

Your monthly payment stays fixed, but the split between principal and interest changes every period

Monthly Payment Formula
M = P × r × (1 + r)ⁿ / [(1 + r)ⁿ − 1]

Where:
M = Monthly principal & interest payment
P = Loan amount (principal)
r = Monthly interest rate (annual rate ÷ 12 ÷ 100)
n = Loan term in months

Each month, interest is charged on the remaining balance (Balance × r), and the rest of the payment reduces principal. Extra payments are applied on top, straight to principal, which lowers the balance interest is charged on for every payment afterward.
📅

Amortization Schedule

A period-by-period table showing payment, interest, principal, and remaining balance from the first payment to payoff — the full picture behind your single monthly payment figure.

Extra Payments & Payoff Date

Add an Extra Monthly Pay, Extra Yearly Pay, or any number of one-time payments and the calculator recalculates your real payoff date, time saved, and total interest saved — every extra dollar goes straight to principal.

📉

Front-Loaded Interest

Because interest is charged on the outstanding balance, early payments are mostly interest. As the balance falls, more of each fixed payment goes toward principal — visible directly in the schedule and the year-wise chart.

💡

Ways to Pay Off Faster

  • Add a small Extra Monthly Pay from day one
  • Apply windfalls (bonuses, refunds) as one-time payments
  • Make an Extra Yearly Pay each year, e.g. a 13th payment
  • Shop for a lower rate — even 0.25% adds up over a long term

⚙️ Why This Formula Works

The monthly payment formula is derived from the present value of an annuity: a fixed periodic payment, discounted back at the monthly rate over n periods, must equal the original principal. Solving for the payment guarantees the balance reaches exactly zero after the final scheduled payment. Each period's interest charge (Balance × r) is calculated fresh on whatever balance remains, so as extra payments shrink the balance faster than scheduled, the interest charge shrinks too — which is exactly why extra payments save more than just their face value in total interest.

🎯 When to Use This Calculator

  • You want the full period-by-period breakdown behind a loan payment, not just the payment figure
  • You're deciding whether an extra monthly payment is worth budgeting for
  • You want to see exactly how a one-time bonus or tax refund payment shortens your loan
  • You need a downloadable schedule for your own records or tax purposes

📋 Assumptions

  • A fixed interest rate for the entire loan term (not adjustable-rate)
  • Every scheduled payment is made on time and in full
  • Extra payments are applied entirely to principal with no prepayment penalty
  • No fees, taxes, or insurance are included unless folded into the loan amount manually

⚠️ Limitations of the Formula

  • Cannot model variable or adjustable interest rates that change mid-term
  • Doesn't include mortgage-specific costs like property tax, PMI, or HOA — use the Mortgage Calculator for that
  • Assumes no missed payments or payment holidays during the term
  • Doesn't account for prepayment penalties some lenders charge on extra payments
Walkthrough

Step-by-Step: How to Use the Amortization Calculator

From loan basics to a full payment-by-payment schedule in under a minute

Enter your loan amount, term, and interest rate

Input the loan principal, the term in years, and the annual interest rate quoted by your lender. Select your currency first if it isn't US Dollars.

Set your loan start date

Enter the date your first payment is due so the payoff date and any one-time payments line up correctly with your real schedule. It defaults to today if left unchanged.

Add any extra payments

Optionally enter an Extra Monthly Pay, an Extra Yearly Pay, or add one or more Extra One-Time Payments with their own amount and date — for a bonus, tax refund, or windfall.

Click Calculate

The calculator computes your fixed monthly payment and simulates the loan month by month, applying interest first and then routing any extra payments straight to principal.

Review your schedule, payoff date, and interest saved

Check your monthly payment, total interest, payoff date, and — if you added extra payments — the interest saved and time saved. Click "Show Full Schedule" to see every payment, not just the first 12.

Example

Worked Example

The calculator's own default loan, with and without a $200 extra monthly payment

Scenario

A $200,000 loan at 6.8% annual interest over a 20-year (240-month) term, starting July 21, 2026 — compared with and without an extra $200 paid every month.

Loan Amount (P)$200,000
Annual Rate6.8%
Term (n)240 months
Monthly Payment$1,526.68
Extra Monthly Pay$200
Start DateJul 21, 2026
Step 1 — Monthly payment: r = 0.068/12 = 0.0056667. M = 200,000 × 0.0056667 × (1.0056667)²⁴⁰ / [(1.0056667)²⁴⁰ − 1] ≈ $1,526.68.
Step 2 — Month 1, with the extra payment: Interest = $200,000 × 0.0056667 = $1,133.33. Principal = $1,526.68 − $1,133.33 = $393.35. Extra = $200. New balance = $200,000 − $393.35 − $200 = $199,406.65.
Step 3 — Baseline (no extra payments): Total interest over the full 240-month schedule = (Monthly Payment × n) − P = ($1,526.68 × 240) − $200,000 = $166,402.98, paid off in exactly 240 months.
Step 4 — With $200 extra every month: The simulation reaches zero balance in 190 months instead of 240 — 4 years 2 months early — with total interest of $126,403.95. Interest saved = $166,402.98 − $126,403.95 = ≈$39,999. Payoff date moves from July 2046 to April 2042.
Interest Saved
$39,999
Time Saved
4y 2m
New Payoff Date
Apr 2042
#DatePaymentExtraPrincipalInterestBalance
1Jul 21, 2026$1,526.68$200.00$393.35$1,133.33$199,406.65
2Aug 21, 2026$1,526.68$200.00$396.71$1,129.97$198,809.95

Explanation: Notice the interest portion drops only slightly between month 1 ($1,133.33) and month 2 ($1,129.97) — that's the front-loaded-interest effect in action, since the balance has barely moved yet. The real payoff comes from compounding: because the $200 extra payment shrinks the balance every single month, less interest accrues on every subsequent payment too, which is why $200/month across 190 months (a total of about $38,000 in extra payments) actually saves closer to $40,000 in interest — the extra payments are effectively earning their own return by avoiding future interest charges.

Interpretation

Understanding Your Results

What your interest-saved and time-saved figures actually tell you

A useful way to judge whether an extra payment plan is worth it is the extra-payment leverage ratio — how many dollars of interest you save for every dollar of extra payment made. It's not a formal industry metric, but it's a practical way to compare different extra-payment strategies.

Interest Saved ÷ Extra PaidGeneral ReadTypical Context
Over 60%High-leverage extra paymentsHigh rate, long remaining term, extra payments started early
25% – 60%Solid, worthwhile savingsTypical mortgage-rate loan with a mid-length remaining term
Under 25%Modest savings — still positive, rarely wastedLow rate, short remaining term, or extra payments started late

Interest saved: this figure compares total interest with your extra payments against the baseline schedule with none. It's always dollar-for-dollar worthwhile as long as your loan carries no prepayment penalty — there's no scenario where paying extra toward principal costs you more in interest.

Time saved: a bigger months-saved figure generally means your extra payments are being applied earlier in the loan (when the balance, and therefore the interest being avoided, is largest) or that the extra amount is large relative to the loan size.

Risk considerations: this calculator assumes a fixed rate and no missed payments. Real-world factors it doesn't model include prepayment penalties, adjustable-rate resets, and the opportunity cost of paying down a low-rate loan early instead of investing that money elsewhere — compare your loan's rate against realistic investment returns before committing to an aggressive extra-payment plan.

ℹ️

This tool provides general financial estimates for educational purposes only and does not constitute personalized financial advice. Confirm whether your loan allows penalty-free extra payments with your lender before relying on the interest-saved and payoff-date figures shown here.

Use Cases

Practical Use Cases for the Amortization Calculator

Where this amortization calculator earns its keep

🏠

Mortgage schedule review

Generate a full amortization table to cross-check against your lender's official schedule.

💵

Extra payment planning

Test different Extra Monthly Pay amounts to find one that fits your budget and payoff goals.

🎁

Windfall allocation

Model exactly how much a bonus, tax refund, or inheritance saves as a one-time payment.

📆

13th-payment strategy

Use Extra Yearly Pay to simulate the classic "extra payment once a year" payoff strategy.

🚗

Auto loan payoff planning

Apply the same schedule logic to a car loan to see interest saved from early payoff.

🎓

Student loan schedule

See the true principal-vs-interest split on a long-term student loan, year by year.

📊

Term comparison

Compare a 15-year vs. 20-year vs. 30-year term's full schedule side by side.

🧾

Recordkeeping & tax prep

Download a full schedule showing interest paid per year for your own financial records.

🌍

Multi-currency loans

Run the same schedule logic across 9 currencies for cross-border loan comparisons.

Pros & Cons

Advantages and Limitations

What this amortization calculator does well, and where it can't replace professional advice

✅ Advantages

  • Generates a full month-by-month amortization schedule, not just a payment figure
  • Models Extra Monthly Pay, Extra Yearly Pay, and unlimited one-time payments together
  • Shows a real payoff date and interest-saved figure, not a rough estimate
  • Supports a custom loan start date so results match your real schedule
  • Toggle between a first-12-payments view and the complete schedule
  • Visual charts for principal-vs-interest split and year-wise breakdown
  • Supports 9 currencies for cross-border loan comparisons
  • Free, instant, and requires no signup or personal information
  • Runs entirely in your browser — your loan details are never sent to a server
  • Downloadable plain-text summary of your results
  • Works for mortgages, auto loans, personal loans, and student loans alike

⚠️ Limitations

  • Assumes a fixed interest rate for the full term — can't model adjustable-rate loans
  • Doesn't include property tax, PMI, HOA fees, or homeowners insurance
  • Doesn't account for prepayment penalties some lenders charge on extra payments
  • Assumes every scheduled payment is made on time with no missed payments
  • Doesn't factor in the opportunity cost of paying down a low-rate loan early
  • Results are estimates — actual lender figures may differ due to rounding or day-count conventions
  • Not a substitute for your lender's official amortization schedule or licensed financial advice
Reference

Extra Payment Strategies Compared

Quick-reference comparison of the three extra-payment options this calculator supports

FeatureExtra Monthly PayExtra Yearly PayExtra One-Time Pay
FrequencyEvery single paymentOnce every 12 paymentsOne specific date, any number of times
Best funded byBudget surplus, automated transferAnnual bonus or 13th-paycheck monthTax refund, inheritance, gift
Interest-saving effectLargest — compounds every monthStrong — front-loaded once a yearStrongest per dollar the earlier it's made
Budget predictabilityRequires consistent monthly disciplineRequires one larger annual commitmentOpportunistic, no ongoing commitment

Common Mistakes and Expert Tips

❌ Common Mistakes

  • Assuming extra payments automatically apply to principal without confirming with your lender
  • Entering the wrong start date, which throws off the payoff date and one-time payment months
  • Ignoring prepayment penalties that some loans still carry
  • Overcommitting to an Extra Monthly Pay that isn't sustainable long-term
  • Forgetting that Total Cost includes principal, not just Total Interest
  • Not comparing the loan's rate against realistic investment returns before prioritizing extra payments

💡 Expert Tips & Best Practices

  • Start extra payments as early as possible in the loan — the interest-avoidance effect compounds over more remaining months
  • Confirm with your lender in writing that extra payments are applied to principal, not future payments
  • Use the full schedule view to check exactly when your balance crosses key milestones
  • Combine a modest Extra Monthly Pay with occasional one-time windfall payments for the biggest impact
  • Re-run the calculator whenever your budget changes to keep your payoff-date estimate current
FAQ

Frequently Asked Questions

Common questions about amortization schedules and extra payments

What is an amortization schedule?
An amortization schedule is a table showing every payment over the life of a loan, broken down into how much goes toward principal and how much toward interest, along with the remaining balance after each payment.
How do extra payments affect my amortization schedule?
Extra monthly, yearly, or one-time payments are applied directly to your loan's principal balance. That reduces the balance interest is charged on for every payment afterward, which shortens your loan term and reduces total interest paid — the calculator recalculates your payoff date and interest saved automatically.
Why does most of my early payment go toward interest?
Interest is charged on the outstanding balance, which is highest at the start of the loan. As the balance shrinks with each payment, less of your fixed payment goes to interest and more goes to principal — this is why amortization schedules are front-loaded with interest.
Can I add more than one extra one-time payment?
Yes. Use "+ Additional One-Time Payments" to add as many one-time payments as you like, each with its own amount and date — for example a tax refund in April and a bonus in December. Each one is applied to the principal balance in the month it falls in.
Does this work for any loan type?
Yes — mortgages, auto loans, personal loans, and student loans are all amortized the same way with fixed periodic payments on a reducing balance, so this calculator works for any of them.
What is the payoff date, and how is it different from my loan term?
Your loan term (e.g. 20 years) is the schedule set when you took the loan. Your payoff date is when the loan is actually projected to reach a zero balance, based on your start date and any extra payments you've added. With no extra payments, the two line up; with extra payments, the payoff date moves earlier.
What's the difference between Extra Monthly Pay and Extra Yearly Pay?
Extra Monthly Pay is added to every single payment throughout the loan. Extra Yearly Pay is added once every 12 payments — like a 13th payment — instead of every month. Both go straight to principal; you can use either, both, or neither, plus any number of one-time payments, together in the same simulation.
Can I use this calculator in currencies other than US Dollars?
Yes, it supports 9 currencies — INR, USD, EUR, GBP, JPY, AUD, CAD, SGD and AED. Switching currency updates the default loan amount, typical rate hint, and all displayed figures instantly.
What happens if I don't enter a start date?
The Start Date field defaults to today's date automatically, so the schedule and payoff date are calculated from the current date unless you change it to match your actual or planned loan start.
Is there a limit to how many one-time payments I can add?
No — click "+ Additional One-Time Payments" as many times as you need to model multiple windfalls, bonuses, or tax refunds across the life of the loan, each with its own amount and date.
How is Total Cost different from Total Interest?
Total Interest is just the interest portion paid over the life of the loan. Total Cost adds that interest to the original loan amount (principal + total interest), giving you the full dollar amount you'll pay back in total.
Can I view the complete amortization schedule, not just the first 12 payments?
Yes, click "Show Full Schedule" below the results table to expand from the default first-12-payments view to every single payment in the loan, in a scrollable table.
Does the calculator account for prepayment penalties or fees?
No, it assumes every extra payment is applied to principal with no penalty. Some loans charge prepayment penalties or restrict extra payments — check your loan agreement before relying on the interest-saved figures shown here.
How much can extra payments actually save on a typical 20-year loan?
It depends on the loan amount, rate, and extra payment size, but the effect compounds meaningfully: on a $200,000 loan at 6.8% over 20 years, adding just $200 extra per month cuts total interest by roughly $40,000 and pays the loan off about four years early. Try different extra payment amounts in the calculator to see the effect on your own numbers.
Learn More

Authoritative Resources on Loan Amortization

Official guidance to complement this calculator — not a substitute for licensed financial advice

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