Mortgage Amortization Calculator
A mortgage amortization calculator shows how a fixed principal-and-interest payment is divided over time and estimates the balance remaining after a chosen number of months. Taxes, insurance, HOA dues, and variable-rate changes are not included.
Quick answer
Early mortgage payments usually contain more interest because the outstanding balance is highest. As principal declines, a larger share of the fixed payment goes to principal.
Calculator
How to use this calculator
- Enter the original mortgage amount.
- Enter the fixed rate and original term.
- Enter the number of payments already made.
- Review principal paid, interest paid, and balance.
Explanation
What it is
A mortgage amortization calculator shows how a fixed principal-and-interest payment is divided over time and estimates the balance remaining after a chosen number of months. Taxes, insurance, HOA dues, and variable-rate changes are not included.
How it works
The calculator finds the fixed payment, then applies the standard remaining-balance formula after the selected number of payments.
When to use it
Use the mortgage amortization calculator when comparing options, setting a realistic target, or checking whether a proposed financial decision fits your broader plan.
Limitations
- The result is an estimate based on the amounts, rates, timing, and assumptions entered.
- Actual product terms, taxes, fees, eligibility rules, and market conditions can change the outcome.
- Use official disclosures or a qualified professional before making a binding financial decision.
Key terms
- Amortization schedule
- A payment-by-payment breakdown of principal and interest.
- Principal
- The amount borrowed that remains unpaid.
- Interest
- The lender’s charge for use of money.
- Remaining balance
- Principal still owed after credited payments.
Formula
The calculator finds the fixed payment, then applies the standard remaining-balance formula after the selected number of payments.
Worked example
A $400,000 30-year mortgage at 6.5% has a fixed principal-and-interest payment. After five years, the balance remains relatively high because early payments contain more interest.
FAQ
How much of my mortgage payment goes to principal?
The share changes each month. Early payments generally contain more interest; later payments contain more principal.
Why is my mortgage balance falling slowly?
Interest is calculated on the outstanding balance, which is highest at the beginning of a long-term loan.
Does this include escrow?
No. It calculates principal and interest only. Property tax, insurance, mortgage insurance, and other charges are separate.
Can I use this for an adjustable-rate mortgage?
Only for a period with a fixed assumed rate. Future adjustments require separate calculations.
Will my lender’s payoff equal this balance?
Not exactly. A payoff quote may include daily interest, fees, unapplied funds, and timing differences.
Common mistakes
- Using an advertised rate without checking whether it applies to the full balance or term.
- Leaving out fees, taxes, timing differences, or irregular cash flows.
- Treating a planning estimate as a guaranteed quote or final professional calculation.
Tips
- Run a conservative scenario as well as an optimistic one.
- Change one assumption at a time so you can see what drives the result.
- Save or export the calculation and update it when rates, costs, or goals change.
Sources and editorial review
Educational estimates only; not personalized financial, tax, legal, lending, investment, or insurance advice.