30-Year Loan Amortization Table Calculator

A 30-year loan amortization table shows how each of 360 monthly payments is divided between interest and principal, and how the balance declines over time. Enter the loan amount and annual interest rate to calculate the monthly payment, total interest, and a month-by-month schedule for a fixed-rate loan.

Formula

The calculator uses the standard fixed-payment loan formula. It finds the monthly payment that pays off the principal and accrued interest in the stated number of monthly payments:

Payment = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2]

• P is the starting loan principal, in dollars.
• r is the monthly interest rate, calculated as annual APR ÷ 1,200. For a 6% APR, r = 0.005.
• n is the number of monthly payments: loan term in years × 12. A 30-year term has 360 payments.
• Payment is the monthly principal-and-interest amount, rounded to the nearest cent.

Total interest in this estimate is monthly payment × number of payments − starting principal. Because it uses the cent-rounded payment, the total follows that payment across the full schedule. A real loan’s final payment may differ slightly if the lender adjusts it to clear a remaining balance.

Worked Example

Using the calculator’s default inputs—$200,000 principal, 6% annual APR, and 30 years:

1. Convert the annual rate to a monthly rate: 6 ÷ 1,200 = 0.005.
2. Find the number of payments: 30 × 12 = 360.
3. Substitute into the payment formula: $200,000 × 0.005 ÷ [1 − (1.005)⁻³⁶⁰].
4. Round the result to cents: the monthly principal-and-interest payment is $1,199.10.
5. Calculate estimated total interest using the rounded payment: $1,199.10 × 360 − $200,000 = $231,676.00.

The payment does not include property-related charges or other amounts that may be collected with a bill. The table below explains how the monthly payment is split; the calculator itself returns summary figures rather than listing all 360 rows.

Assumptions

• The interest rate is fixed for the full term.
• Payments are made monthly, at the end of each monthly period, with the first payment one month after the loan begins.
• Interest accrues monthly using APR divided by 12; the formula assumes monthly compounding.
• Fees, taxes, insurance, private mortgage insurance, escrow, and any extra payments are not included.
• The calculation assumes the loan is fully repaid through equal scheduled payments; lender-specific rounding and payment-date rules may affect exact figures.

How a 30-Year Amortization Table Works

An amortization table, also called an amortization schedule, lays out the loan’s starting balance, payment, interest charge, principal repaid, and ending balance for each payment period. For a fully amortizing 30-year loan with monthly payments, it normally has 360 periods. The word “amortization” refers to paying down the debt over time according to a schedule.

For each row, interest is calculated on the balance at the start of the period. The principal portion is the payment minus that period’s interest, and the ending balance is the starting balance minus principal paid. For example, on the $200,000 loan above, the first month’s interest is $200,000 × 0.005 = $1,000. Of the $1,199.10 payment, about $199.10 reduces principal, leaving a balance of about $199,800.90.

As the balance shrinks, the interest charge generally falls. If the payment remains fixed, more of each later payment goes toward principal. This is why early payments on a long-term loan can appear to make relatively little progress on the balance, even though the scheduled payment is being made.

Reading the Schedule and Total Cost

A full schedule is useful for seeing the timing of principal repayment, but the monthly payment and total interest are only part of the cost of borrowing. The displayed total interest is a model based on the entered APR, term, and fixed monthly payment. To generate individual rows, repeat this calculation for each month: interest = beginning balance × monthly rate; principal = payment − interest; ending balance = beginning balance − principal.

• Beginning balance: the amount owed before that payment’s principal is applied.
• Interest: the period’s borrowing cost under the calculator’s monthly-rate assumption.
• Principal: the part of the payment that reduces the balance.
• Ending balance: the amount carried into the next period.

To inspect a particular month, calculate each row in order; the interest in month 2 depends on the month 1 ending balance. A schedule also helps estimate how much principal has been paid by a selected point, but the exact payoff amount on a specific date can include accrued interest or other contract-specific amounts that this calculation does not model.

Common Mistakes and Limits

A frequent confusion is treating the APR as the monthly rate. The formula requires a monthly rate, so it divides the annual percentage by 12 and converts percent to a decimal: APR ÷ 1,200. Using 6 instead of 0.005 would produce a meaningless result. Also make sure the term is entered in years here; the formula converts it to months.

Another misconception is that a mortgage payment shown in an amortization table must equal the full amount due each month. This calculator estimates principal and interest only. A payment statement may also include escrowed charges or other items, depending on the loan and arrangement. Check the lender’s documents for the actual payment components.

The result is an estimate, not a lender’s official schedule. Adjustable rates, irregular payment dates, extra payments, skipped or late payments, fees, and lender-specific interest calculations can change the actual balance and payoff timing. The formula also does not account for changes in payment amount over the loan term.

Frequently Asked Questions

How many payments are in a 30-year amortization schedule?
A schedule with one payment per month has 360 payments: 30 years × 12 months. A different payment frequency would require a different schedule and formula.

Does a 30-year loan payment include taxes and insurance?
Not in this calculator. Its monthly payment covers estimated principal and interest only. Taxes, insurance, escrow, and other charges are excluded unless they are separately included in a lender’s payment figures.

Why does more of my payment go to interest at the beginning?
Interest is calculated on the outstanding balance. The balance is largest at the beginning, so the interest charge takes up more of a fixed payment. As principal is repaid and the balance falls, the interest portion generally decreases.

Can I use this table if my interest rate changes?
Not as a complete schedule. The calculation assumes one fixed rate for the entire term. If a loan’s rate changes, later payments and interest portions may need to be recalculated using the revised rate and remaining balance.

Why might my lender’s total differ from this estimate?
The lender may use different payment dates, rounding conventions, fees, rate terms, or other contract details. The calculator excludes charges beyond principal and interest and uses a simplified monthly accrual assumption.

This result is an estimate for educational purposes; the lender’s disclosure gives the exact figures.

Related

• PTP Qualifying Income: What Counts and How It Works
• Pell Grant Qualifying Income: What FAFSA Considers
• OHP Qualifying Income: Oregon Health Plan Limits

in p | Loan amount | $ | 200000 | 1 | 100000000
in apr | Interest rate (APR) | % | 6 | 0.01 | 100
in yrs | Loan term | years | 30 | 0.0833 | 50
out pmt | Monthly payment | $ | round(p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)), 2) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2