Weekly Loan Payment Calculator and Formula

A weekly payment report estimates the amount due each week on a fixed-rate loan, along with the total paid and interest over the repayment period. Enter the loan amount, annual percentage rate (APR), and term in years; the calculator assumes 52 equal weekly payments per year.

Formula

The calculator uses the standard level-payment amortization formula, adapted to weekly periods. It converts the annual APR to a weekly rate by dividing by 5,200 (100 for percent, then 52 weeks) and treats the loan term as 52 payment periods per year:

• Weekly payment: A = P × r / [1 − (1 + r)⁻ⁿ]
• Total of payments: T = A × n
• Total interest: I = T − P

Here, P is the starting loan principal in dollars, APR is the annual percentage rate in percent, r = APR / 5,200 is the weekly rate as a decimal, n = years × 52 is the number of weekly payments, A is the payment in dollars, T is the total paid in dollars, and I is the estimated interest in dollars. The payment is rounded to cents; totals use that rounded weekly amount.

Worked Example

Using the calculator’s defaults—$20,000 principal, 8% APR, and a five-year term:

1. Weekly rate: 8 / 5,200 = 0.00153846.
2. Number of payments: 5 × 52 = 260.
3. Insert those values: A = 20,000 × 0.00153846 / [1 − (1 + 0.00153846)⁻²⁶⁰].
4. The weekly payment, rounded to cents, is $93.50.
5. Total of payments: $93.50 × 260 = $24,310.00.
6. Total interest: $24,310.00 − $20,000 = $4,310.00.

Assumptions

• The interest rate is fixed for the entire term.
• Payments are equal, made once every week, with the first payment one week after the loan begins.
• Interest accrues weekly using APR divided by 52; this calculator does not model a lender’s different day-count or compounding convention.
• Fees, taxes, insurance, escrow, late charges, and optional add-ons are not included.

How to Read a Weekly Payment Report

The weekly payment is the recurring amount implied by the inputs, not necessarily the exact amount a lender will collect. The total of payments multiplies that rounded amount by the scheduled payment count. The interest figure is the difference between that total and the original principal; it is not an additional amount to add to the displayed total.

For the example, the report estimates 260 weekly payments of $93.50. Together those payments amount to $24,310, of which $20,000 repays the borrowed principal and $4,310 is estimated interest. In an amortizing loan, each payment generally covers interest accrued for the period and reduces the remaining balance. Early payments usually include a larger interest share than later payments, even though the scheduled payment remains level.

“Weekly” can mean different things in a lender’s schedule. A calendar year has 52 weeks plus an extra day (or two in a leap year), and some contracts calculate interest daily or align payment dates to calendar days. This calculator uses a simplified 52-period year. A lender’s payment schedule and disclosure may therefore differ, especially when payment dates or interest calculations do not match the model.

When to Use It and What It Leaves Out

Use the report to understand the basic relationship between a principal, a stated APR, and a weekly repayment schedule. It can also help you compare scenarios by changing one input at a time—for example, keeping the amount and APR fixed while examining a shorter or longer term. Those calculations describe arithmetic only; they do not establish what a borrower qualifies for or whether a loan is suitable.

The result is not a full repayment ledger. It does not show each week’s opening balance, interest portion, principal portion, or closing balance. Nor does it account for irregular first or final periods, a variable rate, skipped or extra payments, payment holidays, lender fees, or a balloon amount. If any of those apply, the figures need a model that includes the relevant contract details.

APR is entered as a percentage per year, so enter 8 for 8%, not 0.08. The term is in years, while the output payment interval is weekly. Mixing those units is a common source of mistaken estimates. The formula also rounds each scheduled payment to the nearest cent before calculating its totals; a lender may adjust a final payment to clear a small remaining balance.

Common Differences From a Lender’s Figure

A weekly estimate may not match a quote even when the principal, APR, and term appear identical. Check whether the quoted rate is fixed or variable, whether the amount financed includes fees, how often interest compounds, when the first payment is due, and whether the term is stated in weeks, months, or years. Ask for a dated payment schedule if you need the exact sequence of payments and balances.

Another frequent misconception is that paying weekly always means paying less interest than paying monthly. The result depends on the contract’s payment timing, how payments are credited, and how interest accrues. This calculator simply models 52 equal weekly installments at a weekly rate derived from APR; it does not model a monthly payment plan or claim a savings amount from changing frequency.

Frequently Asked Questions

How do I calculate a weekly loan payment?
Convert APR to a weekly decimal rate by dividing the percentage by 5,200, multiply the principal by that rate, and divide by 1 minus (1 plus the rate) raised to the negative number of weekly payments. The calculator applies that formula and rounds the payment to cents.

How many weekly payments are in a five-year loan?
Under the calculator’s 52-payment-per-year assumption, five years contains 260 scheduled weekly payments. A lender’s calendar-based schedule can vary slightly in timing.

Does a weekly payment report include fees?
No. This estimate includes principal repayment and modeled interest only. Fees and other charges must be checked in the lender’s loan documents.

Why is my lender’s weekly payment different?
The lender may use daily interest, a different first-payment date, a different compounding convention, a financed fee, a variable APR, or a final-payment adjustment. Compare the assumptions and request the lender’s payment schedule.

Is the total interest guaranteed?
No. It is an estimate under the inputs and assumptions shown. Changes in rates, payment timing, fees, or actual payment amounts can change the total.

This result is an estimate for education, and 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 | $ | p * (apr / 5200) / (1 - (1 + apr / 5200) ^ -(yrs * 52)) | 2
out tot | Total of weekly payments | $ | pmt * yrs * 52 | 2
out int | Total interest | $ | tot - p | 2