Capital Amortization Table Calculator and Guide

A capital amortization table shows how each scheduled loan payment is divided between interest and repayment of principal, and how the outstanding balance changes over time. Enter a loan amount, annual percentage rate (APR), and term to calculate the level monthly payment and total interest; the formula assumes fixed-rate monthly payments.

Formula

For a fixed-rate loan with equal monthly payments, the payment is the amount that amortizes the starting principal to zero across the scheduled number of months. The periodic interest rate is the APR divided by 1,200, and the number of payments is the term in years multiplied by 12.

Monthly payment: M = round[P × r ÷ (1 − (1 + r)⁻ⁿ), 2].
Total interest: I = M × n − P.

• P is the amount borrowed, in dollars.
• APR is the annual percentage rate entered as a percentage, such as 8 for 8% per year.
• r is the monthly rate, APR ÷ 1,200.
• n is the number of monthly payments, term in years × 12.
• M is the monthly payment, rounded to cents.
• I is estimated total interest over the scheduled term, in dollars.

The calculator gives a payment and aggregate interest, not every row of the table. A full amortization table uses the same monthly steps: calculate interest on the opening balance, subtract that interest from the payment to find principal repaid, then subtract principal repaid from the opening balance.

Worked Example

Using the default inputs—$20,000 principal, 8% APR, and a five-year term:

1. Monthly rate: r = 8 ÷ 1,200 = 0.0066666667.
2. Number of payments: n = 5 × 12 = 60.
3. Unrounded payment: $20,000 × 0.0066666667 ÷ [1 − (1.0066666667)⁻⁶⁰] ≈ $405.5286.
4. Payment rounded to cents: M = $405.53.
5. Total paid using the rounded payment: $405.53 × 60 = $24,331.80.
6. Total interest: $24,331.80 − $20,000 = $4,331.80.

The calculator’s headline result is a monthly payment of $405.53, with estimated total interest of $4,331.80. Actual final-payment handling can differ because lenders may adjust the last installment for rounding or other account details.

Assumptions

• The interest rate is fixed for the full term.
• Payments are equal, made monthly, and occur at the end of each monthly period.
• Interest accrues monthly at APR ÷ 12; the APR is treated as a nominal annual rate for this calculation.
• Fees, taxes, insurance, PMI, escrow, late charges, and other costs are not included.
• The displayed payment is rounded to the nearest cent, and total interest uses that rounded payment for every scheduled month.

How a Capital Amortization Table Works

“Capital” in this context means the loan principal—the amount borrowed or still owed. An amortization table, also called a loan repayment schedule, lays out how that principal is repaid over time. A typical row shows the payment number or date, opening balance, payment, interest portion, principal portion, and closing balance.

For each period, interest is generally calculated against the balance at the start of that period. The principal portion is the payment minus the interest portion. For example, on the first month of the default loan, estimated interest is $20,000 × 0.0066666667, or about $133.33. From the $405.53 payment, about $272.20 therefore goes toward principal, leaving an approximate balance of $19,727.80. Later interest charges fall as the balance falls, so more of each level payment goes toward principal.

Small differences can appear between a calculated schedule and a lender’s statement. Daily interest accrual, payment dates, rounding rules, fees, or a variable rate can change the exact allocation. The loan contract and account disclosure determine the actual amounts.

How to Read the Results

The monthly payment is the scheduled amount for principal and interest under the assumptions above. It is not necessarily the full amount due on a bill. A mortgage payment, for example, may also include items such as taxes or insurance, while other loans may have separate fees. Those items are not calculated here.

Total interest is the sum implied by the rounded scheduled payment over the entire term, minus the original principal. It is not the total amount paid: add principal to interest to get the modeled total payments. It also is not necessarily the loan’s total borrowing cost if charges outside principal and interest apply.

An amortization table is useful for seeing how the balance declines, estimating the interest component of scheduled payments, or checking how a stated term translates into regular installments. To construct rows manually, repeat the monthly calculation using each new balance; do not calculate every month’s interest from the original loan amount.

Common Mistakes and Limits

• Entering APR as a decimal: enter 8 for 8%, not 0.08. The formula divides the percentage input by 1,200.
• Confusing term units: this calculator takes years and converts them to months. A five-year term means 60 payments, not five.
• Assuming payment equals total housing or borrowing cost: the result covers modeled principal and interest only.
• Ignoring rounding: the monthly payment is rounded to cents before total interest is calculated. A lender may handle cents and the last payment differently.
• Applying a fixed-rate formula to changing terms: a variable rate, irregular payment, interest-only period, or extra payment requires a schedule that models those changes.

The formula requires a positive rate and a regular payment schedule. It is a standard estimate for level-payment amortization, not a reconstruction of a specific account. To match a real loan, use the lender’s principal, applicable rate, payment frequency, dates, and disclosed charges.

Frequently Asked Questions

What does a capital amortization table show?
It shows each scheduled payment’s interest and principal portions and the remaining balance after payment. The exact columns vary, but these are the core figures.

Why does more of the payment go to interest at the beginning?
Interest is calculated on the outstanding balance. That balance is largest at the start, so the interest portion is larger; as principal is repaid, the interest portion generally declines.

Is an amortization table the same as an interest schedule?
No. An interest schedule may show interest charges alone. An amortization table also tracks principal repayment and the resulting balance.

Does the monthly payment include taxes and insurance?
No. This calculation estimates scheduled principal and interest only. Taxes, insurance, escrow, fees, and other charges are outside the formula.

Can I use this for a variable-rate loan?
Only as an estimate for a period with a specified rate. A changing rate alters future interest and may change the payment or payoff timeline; this calculator does not model rate resets.

Why might the lender’s final payment differ?
Rounding, payment timing, daily interest calculations, fees, or adjustments to the account can produce a different final amount from a simple monthly estimate.

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

Related

• Annual Loan Amortization Table: Formula and Example
• Amortization Table Example: Monthly Loan Breakdown
• Amortization Table in Excel: Formula and Example

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 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