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Mortgage Amortization Calculator

View the complete amortization schedule for any mortgage. See exactly how each payment is split between principal and interest, year by year.

Calculation Inputs

Additional principal payment per month to pay off the loan faster.

Results computed instantly — your data never leaves your device.

Live Results

Real-Time

Monthly Payment (P&I)

$2,096.83

Total Interest

$434,858.31

Total Amount Paid

$754,858.31

Payoff Time

30y 0m

100% Client-SidePrivate & Secure
View Schedule:

Year-by-Year Summary

Click a row to expand monthly detail

YearPrincipalInterestTotal PaidBalanceCum. Interest

How to Use the Mortgage Amortization Calculator

  1. 1

    Enter your loan amount — the total you are borrowing (home price minus down payment).

  2. 2

    Enter the annual interest rate and loan term in years.

  3. 3

    Optionally add an extra monthly payment to model accelerated payoff.

  4. 4

    Switch between "Yearly" and "Monthly" views; click any year row to expand the monthly detail.

Formula & Mathematical Basis

M = L × [r(1+r)^n] ÷ [(1+r)^n − 1] Interest_k = Balance_(k-1) × r Principal_k = M − Interest_k Balance_k = Balance_(k-1) − Principal_k

Variable Key

M

Fixed monthly payment (Principal & Interest)

L

Loan amount (principal)

r

Monthly interest rate = Annual Rate ÷ 12 ÷ 100

n

Total number of monthly payments = years × 12

Balance_k

Outstanding loan balance after payment k

Interest_k

Interest portion of payment k

Principal_k

Principal portion of payment k

📝 Extra principal payments reduce the outstanding balance immediately, so subsequent interest charges are lower. This compounds: every dollar of extra principal paid early saves more than a dollar of interest over time.

Step-by-Step Examples

1

Standard 30-year mortgage

Scenario: $320,000 loan at 6.85% for 30 years, no extra payments.

  1. 1.Monthly rate r = 6.85 ÷ 12 ÷ 100 = 0.005708.
  2. 2.n = 360 payments.
  3. 3.M = 320,000 × [0.005708 × (1.005708)^360] ÷ [(1.005708)^360 − 1] ≈ $2,103/mo.
  4. 4.Month 1: Interest = $320,000 × 0.005708 = $1,827; Principal = $276.
  5. 5.Month 360: Interest ≈ $12; Principal ≈ $2,091.
  6. 6.Total interest = $2,103 × 360 − $320,000 ≈ $437,000.
✅ Monthly payment: $2,103 | Total interest over 30 years: ~$437,000
2

Same loan with $300/mo extra payment

Scenario: $320,000 at 6.85%, 30-year term, $300 extra per month.

  1. 1.Base payment: $2,103/mo. Total monthly: $2,403.
  2. 2.Extra $300 applied to principal each month, reducing balance faster.
  3. 3.Lower balance → less interest each subsequent month.
  4. 4.Payoff achieved in approximately 22 years (instead of 30).
✅ Payoff in ~22 years | Interest saved: ~$110,000 | Months saved: ~96

Practical Use Cases

  • Planning extra principal payments to shorten payoff and reduce total interest
  • Comparing 15-year vs 30-year mortgage total costs
  • Determining how many payments remain on an existing mortgage
  • Satisfying lender or accounting requirements for loan documentation
  • Real estate investment analysis — projecting equity build-up year by year
  • Refinancing decisions — comparing new schedule vs remaining old schedule

Common Mistakes to Avoid

  • Assuming all extra payments reduce principal — confirm with lender that prepayments apply to principal, not future scheduled payments.
  • Ignoring escrow: the amortization schedule covers P&I only; property tax and insurance are separate.
  • Not accounting for the interest saved when comparing paying points upfront vs a lower rate over time.
  • Overlooking that private mortgage insurance (PMI) is cancelled once LTV reaches 80%, reducing total cost.

Glossary of Terms

Amortization
Gradual repayment of a debt over time through regular installments that cover both interest and principal.
Principal
The outstanding balance of the loan, excluding accrued interest.
Negative Amortization
When monthly payments are less than the interest owed, causing the outstanding balance to grow. Not possible with standard fixed-rate loans.
Equity
The portion of the home value you own outright: current home value minus outstanding loan balance.
Prepayment
Any payment toward principal beyond the scheduled monthly amount, reducing the outstanding balance and future interest charges.

Frequently Asked Questions

What is an amortization schedule?

▾
An amortization schedule is a complete table of every loan payment showing how much goes to principal, how much to interest, and the remaining balance after each payment. Early payments are mostly interest; later payments shift toward principal.

How much interest can I save with extra payments?

▾
Even small extra payments applied to principal dramatically reduce total interest. For example, paying $200/month extra on a $300,000, 30-year loan at 6.85% saves over $90,000 in interest and pays off the loan ~8 years early.

What is the difference between the monthly payment and total paid?

▾
Your monthly payment is fixed (P&I). Total paid is that payment times the number of payments. The difference between total paid and your original loan amount is the total interest you pay over the life of the loan.

Why does so much of my early payment go to interest?

▾
Because interest accrues on the outstanding balance each month. When the balance is high (early in the loan), so is the interest charge. As you pay down principal, the interest portion shrinks and the principal portion grows — this is amortization.

Can I use this for any loan type?

▾
Yes. This calculator works for any fixed-rate fully-amortizing loan: 30-year mortgages, 15-year mortgages, refinances, home equity loans, and personal loans.

Sources & References

  1. [1]
  2. [2]
    Understanding Your Mortgage Statement— Federal Reserve, 2023

CalculatorFree Real Estate Finance TeamLicensed Mortgage Broker Review & Actuarial Verification

Amortization logic verified against Fannie Mae loan calculation standards and CFPB disclosure requirements.

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