Amortization Calculator
Generate a full amortization schedule showing principal, interest, and balance for each payment period with extra payment support.
Reviewed by CalculatorApp.me Finance Team
Amortization Calculator β Complete Guide
Loan schedules, payment breakdowns, extra payment strategies, and mortgage amortization explained.
$1,768
Avg 30-yr payment ($350K/6.5%)
$286K
Total interest on $350K mortgage
63%
Interest portion of 1st payment
30 yrs
Standard amortization period
What Is Loan Amortization?
Amortization is the process of paying off a loan through regular, equal payments over time. Each payment is split between interest (charged on the remaining balance) and principal (reducing the balance). Early payments are heavily weighted toward interest, while later payments mostly reduce principal.
For a typical 30-year, $350,000 mortgage at 6.5%, the monthly payment is $2,212 (principal & interest only). In the first payment, $1,896 goes to interest and only $316 to principal. By the last payment, $2,198 goes to principal and just $14 to interest. Over the full term, you pay approximately $286,000 in total interest β almost the loan amount itself.
Our amortization calculator generates a complete payment schedule showing exactly how each payment is allocated, the balance after each payment, and the cumulative interest paid. You can model extra payments to see how prepaying principal dramatically reduces total interest and loan duration.
Amortization Formulas
M = P Γ [r(1+r)^n] / [(1+r)^n β 1]
Where:
P = Loan principal
r = Monthly interest rate (annual/12)
n = Total number of payments
Example ($350,000 at 6.5%, 30 years):
r = 0.065/12 = 0.005417
n = 360
M = $350,000 Γ [0.005417(1.005417)^360]
/ [(1.005417)^360 β 1]
M = $2,212.24/monthThis is the standard fixed-rate amortization formula used by all lenders.
Interest portion = Balance Γ Monthly Rate Principal portion = Payment β Interest portion New Balance = Old Balance β Principal portion Month 1 ($350K at 6.5%): Interest = $350,000 Γ 0.005417 = $1,895.83 Principal = $2,212.24 β $1,895.83 = $316.41 New Balance = $349,683.59
Early payments are ~86% interest. By month 180, the split is roughly 50/50.
Extra $200/month on $350K, 6.5%, 30yr: Base: 360 payments, $446,007 total interest With extra: 277 payments, $342,186 interest Savings: β’ $103,821 in interest saved β’ 83 fewer payments (6.9 years earlier) β’ Break-even: immediate Yield equivalent: ~6.5% guaranteed, tax-free
Extra principal payments offer a guaranteed return equal to your interest rate.
B(k) = P Γ [(1+r)^n β (1+r)^k] / [(1+r)^n β 1]
Where k = payments already made
Example (balance after 5 years / 60 payments):
B(60) = $350,000 Γ [(1.005417)^360 β (1.005417)^60]
/ [(1.005417)^360 β 1]
B(60) = $328,269
After 5 years, only $21,731 principal repaid
(from $132,735 total paid!)After 5 years of a 30-year loan, you've repaid only ~6% of the principal.
Sample Amortization Schedule ($350,000 at 6.5%, 30yr)
| Payment # | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $2,212.24 | $316.41 | $1,895.83 | $349,683.59 |
| 12 | $2,212.24 | $337.28 | $1,874.96 | $346,086.52 |
| 60 | $2,212.24 | $438.17 | $1,774.07 | $327,064.51 |
| 120 | $2,212.24 | $605.47 | $1,606.77 | $296,061.59 |
| 180 | $2,212.24 | $836.47 | $1,375.77 | $253,574.67 |
| 240 | $2,212.24 | $1,155.50 | $1,056.74 | $193,685.92 |
| 300 | $2,212.24 | $1,596.27 | $615.97 | $112,000.75 |
| 360 | $2,212.24 | $2,198.33 | $13.91 | $0.00 |
Principal portion grows from $316/mo to $2,198/mo β interest decreases proportionally.
History of Amortized Loans
FHA Introduces Amortized Mortgages
Before the 1930s, most home loans were interest-only with balloon payments. The Federal Housing Administration (FHA) introduced fully amortizing, 15-year fixed-rate mortgages β revolutionizing homeownership.
National Housing Act
The National Housing Act of 1934 created the FHA, establishing standards for mortgage lending including 20% down payments, fixed rates, and amortization schedules that banks nationwide adopted.
30-Year Mortgage Becomes Standard
Post-WWII housing demand drove lenders to extend mortgage terms to 30 years, reducing monthly payments by ~25% compared to 15-year terms and making homes accessible to middle-class Americans.
Truth in Lending Act (TILA)
Congress passed TILA requiring lenders to disclose APR, total interest costs, and amortization details. For the first time, borrowers could see the true cost of their loans.
Tax Reform Act β Mortgage Interest Deduction
The Tax Reform Act preserved the mortgage interest deduction while eliminating deductions for other consumer interest. This made mortgages the most tax-advantaged consumer debt.
Dodd-Frank and Qualified Mortgages
After the 2008 financial crisis, the Dodd-Frank Act established 'Qualified Mortgage' rules requiring fully amortizing payments, banning negative amortization, and capping debt-to-income ratios.
Key Research & Data
Federal Reserve
Mortgage Debt Outstanding
Total US mortgage debt reached $12.52 trillion in Q4 2023, accounting for 70% of all household debt. The average mortgage balance is approximately $244,000.
Consumer Financial Protection Bureau
Explore Interest Rates Tool
CFPB data shows the median 30-year fixed rate was 6.81% in Q4 2023. Even a 0.5% rate difference on $350K changes total interest by ~$40,000 over the loan term.
Freddie Mac β PMMS
Primary Mortgage Market Survey
Freddie Mac's weekly survey tracks mortgage rates since 1971. The all-time low was 2.65% (Jan 2021) and the 52-year average is approximately 7.74%.
National Association of Realtors
Home Affordability Index
NAR's affordability index fell to 91.7 in 2023 (below 100 = unaffordable for median family). Understanding amortization helps buyers evaluate true housing costs beyond the sticker price.
Amortization Myths vs. Facts
A 15-year mortgage payment is double a 30-year payment.
A 15-year payment is only ~40% higher than a 30-year. On $350K at 6.5%, payments are $3,049/mo (15yr) vs. $2,212/mo (30yr) β and you save $194,000+ in total interest.
Making extra payments isn't worth it with low interest rates.
Extra payments offer a guaranteed, tax-free return equal to your interest rate. Even at 4%, paying an extra $200/month on a $300K mortgage saves $44,000 and cuts 5 years off the term.
You should always choose the longest mortgage term for flexibility.
Longer terms cost dramatically more in interest. A 30-year $350K mortgage at 6.5% costs $446K in interest vs. $252K for a 15-year term β $194K more for the same house.
Refinancing always saves money.
Refinancing involves 2-5% closing costs ($7,000-$17,500 on $350K). You need to stay long enough for monthly savings to exceed costs β the 'break-even point' is typically 2-4 years.
Frequently Asked Questions
What does amortization mean?βΌ
Why do I pay so much interest at the beginning?βΌ
How do extra payments reduce my loan?βΌ
Should I choose a 15-year or 30-year mortgage?βΌ
What is negative amortization?βΌ
How does my amortization schedule change with a different rate?βΌ
Can I get an amortization schedule from my lender?βΌ
What is the difference between amortization and depreciation?βΌ
Does rounding my payment up help?βΌ
What is a fully amortizing loan vs interest-only?βΌ
How do adjustable-rate mortgages (ARMs) affect amortization?βΌ
Is mortgage interest tax deductible?βΌ
References
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Browse Finance Calculators βMethodology, sources & limitations
This calculator uses a published formula and the values entered in the calculator to generate the result.
- Formula
- PMT = P Γ [r(1+r)^n] / [(1+r)^n - 1]
- Jurisdiction & units
- Intended for US, IN, EU, GB, AU, CA. Supports both units where applicable.
- Assumptions & limitations
- Results use the inputs you provide and published formulas or rate assumptions. They are estimates, not financial, tax, lending, or investment advice.
- Review status
- Formula and automated QA completed June 21, 2026; independent professional review is pending. Next scheduled review: September 21, 2026.
Validation sources
- CFPB Amortization Guide
- Fannie Mae
Amortization Calculator β Answer & Method
Generate a full loan amortization schedule showing principal and interest breakdown per payment.
Formula: Amortization Payment
PMT = P Γ [r(1+r)^n] / [(1+r)^n - 1]
Example Calculation
$200K at 6.5% for 30 years: $1,264/month, $255,360 total interest.
Important limitation
This is an estimate based on your inputs, not financial, lending, tax, or investment advice.
Key Facts
- In an amortization schedule, early payments are mostly interest while later payments are mostly principal.