Weekly Amortization Table Calculator and Guide

A weekly amortization table shows how each weekly loan payment is split between interest and principal, and how the balance changes after every payment. Enter the loan amount, annual percentage rate (APR), and term to calculate the weekly payment and total interest; the results use a standard fixed-rate schedule with 52 payments per year.

Formula

The calculator uses a level-payment amortization formula, adapted to weekly periods. It assumes the annual APR is divided by 52 to obtain a weekly rate, and that the borrower makes 52 equal payments each year:

Weekly payment = round(P × r / [1 − (1 + r)⁻ⁿ], 2)

• P is the starting principal, or loan amount, in dollars.
• r is the periodic interest rate as a decimal: APR ÷ 5,200. For an 8% APR, r = 0.08 ÷ 52.
• n is the number of weekly payments: loan term in years × 52.
• Weekly payment is rounded to the nearest cent.

Total interest is estimated as weekly payment × n − P. Because the payment is rounded to cents before the total is calculated, this figure reflects repeated payments at that rounded amount. Actual loan servicing may adjust the final payment to clear a small remaining balance.

Worked Example

Using the calculator’s defaults—$20,000 principal, 8% APR, and a five-year term—the schedule contains 5 × 52 = 260 weekly payments. The weekly rate is 0.08 ÷ 52 = 0.0015384615.

1. Calculate the payment: $20,000 × 0.0015384615 ÷ [1 − (1 + 0.0015384615)⁻²⁶⁰].
2. The unrounded payment is about $93.13; rounded to cents, the weekly payment is $93.13.
3. Total scheduled payments are $93.13 × 260 = $24,213.80.
4. Estimated total interest is $24,213.80 − $20,000 = $4,213.80.

These outputs summarize the schedule. A complete amortization table would show 260 rows, one for each payment. In each row, interest is calculated on the balance at the start of the period, the remainder of the payment reduces principal, and the new balance becomes the starting balance for the next row.

Assumptions

• The APR stays fixed throughout the loan term.
• Payments are equal, made weekly at the end of each period, with 52 periods per year.
• Interest accrues using a weekly periodic rate equal to APR divided by 52; this is not a daily-interest calculation.
• Fees, taxes, insurance, escrow, and other charges are not included.

How a Weekly Amortization Table Works

Amortization means paying down a debt through scheduled payments that cover both interest and principal. At the beginning of a fully amortizing loan, the outstanding balance is larger, so a larger share of each level payment goes to interest. As the balance falls, the interest portion generally shrinks and more of each payment goes toward principal. The payment stays level under this calculator’s assumptions, while its components change.

For an illustrative early row in the example, the first week’s interest is approximately $20,000 × (0.08 ÷ 52) = $30.77. Subtracting that from the $93.13 payment leaves about $62.36 to reduce principal, leaving a balance near $19,937.64. Calculations performed with full precision can differ by a cent from figures reconstructed from rounded display values.

A spreadsheet or lender statement may show a different schedule if it uses daily accrual, a different payment date, a nonstandard year convention, fees added to the balance, or a final-payment adjustment. The contract or lender’s repayment disclosure is the reference for the actual schedule.

When Weekly Payments Differ from Monthly Payments

Weekly means one payment each week, or 52 payments in a year. It does not automatically mean “pay one-quarter of the monthly payment every week.” Those methods can produce different payment totals and payoff timing. A common budgeting arrangement divides a monthly amount into four weekly transfers, but four weeks do not equal a full calendar month over a year: 4 × 12 is 48, not 52.

Likewise, making a payment every two weeks is a separate schedule with 26 payments per year. It should not be treated as the same thing as weekly payments. When comparing schedules, check the number of payments per year, how interest accrues, whether extra amounts are applied to principal, and whether the lender has fees or timing conditions. This calculator models only 52 equal weekly payments each year.

Reading and Using the Results

The weekly payment is the estimated recurring principal-and-interest amount under the stated assumptions. Total interest is the sum of those modeled payments minus the original principal; it is not a separate bill due at the start. The calculation does not show every balance row, so it is useful for estimating the payment and interest total, not for reproducing a lender’s account history.

To build a full table, repeat these calculations for each week:

• Interest for the week = opening balance × weekly rate.
• Principal repaid = scheduled payment − interest for the week.
• Closing balance = opening balance − principal repaid.

Use the closing balance as the next week’s opening balance. Keep internal figures at higher precision if possible, then round displayed currency to cents. Rounding every intermediate value too early can make the last rows diverge from a lender’s schedule.

Common Limits and Mistakes

• Confusing APR with the weekly rate: enter APR as a yearly percentage, such as 8, not 0.08. The formula converts it to a weekly decimal rate.
• Assuming every lender uses 52 identical periods: real contracts can calculate accrued interest by day or use other conventions.
• Comparing unlike terms: the same principal and APR can produce different payments and total interest when the term changes.
• Treating a rounded estimate as a payoff quote: payment dates, accrued interest, fees, and rounding may affect the amount needed to close a loan.
• Ignoring extra payments: this model has no input for additional principal payments, skipped payments, or changing rates, so it cannot predict their effects.

The standard formula assumes a positive fixed APR and regular equal payments that fully repay the loan over the specified term. It is not suitable as an exact schedule for interest-only periods, irregular payment dates, variable rates, balloon payments, or loans with charges folded into the balance.

Frequently Asked Questions

What is a weekly amortization table?
A table listing each weekly payment, the amount applied to interest, the amount applied to principal, and the balance remaining afterward.

How do I calculate a weekly loan payment?
Convert APR to a weekly decimal rate by dividing it by 5,200, set the number of payments to years × 52, then use the level-payment formula shown above.

Is weekly payment the same as biweekly payment?
No. Weekly means 52 scheduled payments per year; biweekly means 26. Their payment amounts and yearly totals are different.

Why does my lender’s figure differ from this estimate?
The lender may use daily interest, different payment timing, fees, a different rounding method, or a schedule that does not contain exactly 52 equal periods per year.

Does a weekly schedule always reduce total interest?
Not by itself. The result depends on the amount paid, payment timing, interest calculation, and how payments are applied. This calculator only estimates the fixed-rate, equal-weekly-payment case.

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

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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 | Weekly payment | $ | round(p * (apr / 5200) / (1 - (1 + apr / 5200) ^ -(yrs * 52)), 2) | 2
out int | Total interest | $ | pmt * yrs * 52 - p | 2