Weekly Amortization Schedule Calculator

A weekly amortization schedule shows how each weekly payment is divided between interest and principal, and how the balance changes over time. Enter the loan amount, annual interest rate, and term to estimate the weekly payment, total interest, and payment-by-payment schedule.

Formula

This calculator estimates a level weekly payment using a fixed annual percentage rate divided into 52 weekly periods. The payment formula is:

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

• P is the starting loan principal, in dollars.
• r is the rate per week, calculated as APR ÷ 5,200. APR is entered as a percentage per year, so 8% becomes 0.08 ÷ 52.
• n is the number of weekly payments, calculated as term in years × 52.
• Weekly payment is rounded to the nearest cent before the totals are calculated.

Total payments are the rounded weekly payment multiplied by the number of scheduled weeks. Estimated total interest is total payments minus the original principal. Since the payment is rounded to cents, the final amount may differ slightly from a schedule that adjusts its last payment to clear the remaining balance exactly.

Worked Example

Using the calculator’s defaults—$20,000 principal, 8% APR, and a five-year term—the schedule has 5 × 52 = 260 weekly payments. The periodic rate is 8 ÷ 5,200 = 0.00153846, or about 0.153846% per week.

Substituting those values into the payment formula gives:

Weekly payment = round($20,000 × 0.00153846 ÷ [1 − (1.00153846)⁻²⁶⁰], 2) = $94.19

Total scheduled payments are $94.19 × 260 = $24,489.40. Estimated interest is $24,489.40 − $20,000 = $4,489.40. These totals use the rounded payment, as the calculator does.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are made once every week, with the first payment one week after the schedule begins.
• Interest is modelled weekly at APR ÷ 52. This is a periodic-rate estimate, not a daily-interest calculation.
• The calculation excludes fees, taxes, insurance, PMI, escrow, late charges, and any other amount not entered.
• The displayed total assumes the same rounded payment for every scheduled week; actual contracts may adjust the final payment or use a different accrual method.

How a Weekly Amortization Schedule Works

Amortization is the gradual repayment of a debt through scheduled payments. Each payment covers the interest accrued for the period, and the remainder reduces principal. Early in a standard amortizing loan, the outstanding balance is larger, so more of the payment goes to interest. As principal falls, the interest portion generally shrinks and more of each unchanged payment reduces principal.

A detailed schedule usually has one row per payment and columns for the payment number or date, opening balance, payment amount, interest, principal repaid, and closing balance. For a weekly period, a simplified row is calculated as follows:

• Weekly interest = opening balance × weekly rate.
• Principal repaid = payment − weekly interest.
• Closing balance = opening balance − principal repaid.

For example, with a $20,000 opening balance and the example weekly rate of about 0.00153846, the first week’s estimated interest is about $30.77. From the $94.19 payment, about $63.42 reduces principal, leaving an estimated balance of $19,936.58. Figures in a real schedule can differ because of payment dates, rounding, and the lender’s interest method.

Weekly Payments Compared With Monthly Payments

A weekly schedule has more frequent payment periods than a monthly schedule, but it is not automatically equivalent to dividing a monthly bill by four. A year has 52 weeks, while 12 months do not each contain exactly four weeks. Consequently, a weekly payment that is one quarter of a monthly payment would produce 52 payments annually, not 48.

Comparisons also depend on how the rate is applied and when payments are credited. This calculator uses APR divided by 52. Some contracts accrue interest daily or specify another convention, so multiplying a monthly payment by 12 and comparing it with a weekly payment times 52 may not reproduce the lender’s accounting. To compare schedules, use the same principal, rate basis, start date, and overall payoff period, and check the contract’s payment and interest terms.

Reading the Estimate and Common Pitfalls

The weekly payment is a level-payment estimate, not a complete lender quote. Total payments and interest assume that every scheduled payment is made on time and that no extra principal is paid. The calculation also treats the term as exactly 52 weeks per year; actual calendar dates and contract schedules may include timing variations.

• Enter APR as a percentage. Enter 8 for 8%, not 0.08. The formula performs the conversion.
• Use the loan principal only. Add financed costs to the amount only if they are part of the amount being modelled.
• Do not confuse payment frequency with interest timing. Weekly payments do not prove that a lender calculates interest weekly.
• Expect rounding differences. A cent-level payment multiplied over many periods can leave a small residual; a lender may vary the last payment.
• Check irregular terms. The calculator represents the term as years × 52. It does not generate dated payment rows or account for skipped, late, or extra payments.

For an actual amortization table, the lender’s disclosure or account statement is the source for the contracted payment dates, rate method, fees, and final payment calculation.

Frequently Asked Questions

What is a weekly amortization schedule?
A table showing each weekly payment and its estimated allocation to interest and principal, along with the balance remaining after each payment.

How do I calculate a weekly loan payment?
Convert APR to a weekly rate by dividing by 5,200 when APR is entered as a percentage, set the number of payments to years × 52, and apply the level-payment formula shown above.

Does paying weekly reduce total interest?
It depends on the contract’s interest calculation, payment crediting, and the compared schedule. This estimate models weekly periods; it does not establish the savings for a particular loan.

Is a weekly payment one-fourth of a monthly payment?
Not necessarily. A year contains 52 weekly payments, so a weekly amount equal to one-fourth of a monthly amount would yield 13 four-week groups in a year, not 12.

Why might my lender’s schedule differ?
The lender may use daily interest, different payment dates, fees, a variable rate, different rounding, or a final-payment adjustment that this estimate does not model.

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

Related

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in bal | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.01923 | 50
out pmt | Weekly payment | $ | round(bal * (apr / 5200) / (1 - (1 + apr / 5200) ^ -(yrs * 52)), 2) | 2
out tot | Total payments | $ | pmt * yrs * 52 | 2
out int | Total interest | $ | tot - bal | 2