Deferred Payment Loan Calculator: Payments and Interest

A deferred payment loan calculator estimates the level monthly payment and total interest after a period with no required payments. Enter the loan amount, annual percentage rate (APR), and repayment term; the estimate assumes repayment begins immediately and does not model the deferral period itself, so use the adjusted balance at repayment if interest accrues during deferment.

Formula

This calculator uses the standard fixed-payment amortizing-loan formula, treating the amount entered as the balance when scheduled repayment starts. It does not calculate how that balance changed while payments were deferred.

Monthly payment: M = round(P × r ÷ [1 − (1 + r)⁻ⁿ], 2), where r = APR ÷ 1,200 and n = 12 × T.

• P is the loan balance at the start of repayment, in dollars.
• APR is the entered annual percentage rate, in percent.
• r is the monthly rate as a decimal.
• T is the repayment term, in years; n is the number of monthly payments.
• M is the monthly payment, rounded to the nearest cent.

Total interest estimate: I = M × n − P. Since the payment is rounded to cents first, this total uses the displayed monthly payment multiplied by the number of scheduled payments, then subtracts the starting balance. Actual final payments can differ because lenders may adjust the last payment for rounding or the exact payoff date.

Worked Example

Using the calculator’s default values: a $20,000 balance, 8% APR, and a five-year repayment term.

1. Convert the APR to a monthly decimal rate: r = 8 ÷ 1,200 = 0.0066667.
2. Find the payment count: n = 5 × 12 = 60 months.
3. Substitute: M = 20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰].
4. The unrounded payment is about $405.53; rounded to cents, the monthly payment is $405.53.
5. Total interest estimate: $405.53 × 60 − $20,000 = $4,331.80.

Assumptions

• The rate stays fixed throughout the repayment term.
• Payments are equal monthly payments, made at the end of each month, with the first payment one month after repayment begins.
• Interest is modelled monthly at APR divided by 12.
• The calculation excludes fees, taxes, insurance, penalties, and any other charges or credits.
• The entered principal is the balance on the date repayment begins; deferred-period interest or capitalization must be included in that balance if applicable.

What Deferred Payment Means

A deferred payment loan postpones some or all scheduled payments for an agreed period. “Deferred” describes when payment is due; it does not by itself mean interest stops accumulating. Depending on the contract, interest may accrue during the pause, be paid during it, be added to principal, or be handled under another arrangement. The specific agreement and lender disclosure determine the treatment.

That distinction matters because the balance at repayment can be greater than the amount originally borrowed. If interest accrues and is added to principal, later interest may be calculated on the increased balance as well. The calculator does not infer those terms from the word “deferred.” Enter the amount actually scheduled to be repaid, if known, rather than assuming the original loan amount remains unchanged.

How to Use and Read the Estimate

• Enter the repayment-start balance, not automatically the amount first disbursed.
• Enter APR as a percentage per year: for example, type 8 for 8%, not 0.08.
• Enter the length of the repayment phase in years. The calculator converts it to monthly payments.
• Read the first result as the estimated monthly payment and the second as estimated interest across the stated term.

The payment is a level-payment estimate under the formula’s assumptions. It is not a quote, payoff statement, or confirmation of the amount due on a particular date. If your contract uses daily interest, changing rates, irregular payment dates, or a different payment schedule, results may not match its figures.

Deferred-Period Interest and Common Mistakes

A common misconception is that a payment pause automatically makes a loan interest-free. Check the loan documents for whether interest accrues and what happens to unpaid interest. For a simple illustration only, if a $20,000 balance accrued 8% annual interest for one year with no payments, simple interest would be $1,600 (20,000 × 0.08 × 1). If unpaid interest were added to principal, the balance would become $21,600 under that simplified assumption. Actual contracts may calculate interest differently, so this illustration is not a substitute for the lender’s balance figure.

• Mixing up loan amount and repayment balance: interest added during deferment can change the principal used for later payments.
• Entering APR as a decimal: enter 8 for 8%, because the calculator divides the percentage by 1,200.
• Confusing deferment with forgiveness: postponing payment does not, by itself, erase principal or interest.
• Ignoring rounding: multiplying a cent-rounded payment by all months gives an estimate; the final scheduled payment can be adjusted.
• Using the full loan term by mistake: if the term entered is meant to describe repayment, do not include the preceding deferred months.

Limits and Useful Information to Check

Before interpreting a result, identify the balance due when repayment begins, the exact start date, whether interest accrues during the pause, how it is calculated, and whether unpaid interest is capitalized. Also confirm the repayment frequency, rate type, payment count, and any fees or charges that affect the amount due. If you do not know the repayment-start balance, ask the lender or servicer for an estimate or current disclosure rather than treating this calculator’s result as that balance.

The calculator models only ordinary monthly amortization after the entered balance and rate are supplied. It does not model interest-only periods, balloon payments, graduated or income-based payments, skipped installments, variable APRs, or payment holidays embedded in the repayment schedule. Such terms require a calculation that reflects the actual schedule.

Frequently Asked Questions

Does interest accrue during deferred payments?
It depends on the loan terms. A payment deferral does not necessarily pause interest. Check the agreement or request the projected balance at the end of the deferral.

Does deferred interest get added to the loan balance?
It may be added, paid separately, or treated another way under the contract. If it is added to principal, use the resulting repayment-start balance as the calculator’s loan amount.

Can I enter the original loan amount?
Only if that is also the balance when scheduled repayment starts. If the balance changes during deferment, use the updated figure for an estimate of subsequent payments.

Why is the lender’s payment different?
The lender may use a different balance, rate convention, payment date, term, rounding method, or include charges that this estimate excludes. Compare the inputs and the repayment schedule.

Does this calculator show the amount due during deferment?
No. It estimates payments after repayment begins and assumes the entered balance is already known. It does not determine whether payments are required during the deferred period.

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

Related

• VA Budget Breakdown: How a VA Loan Payment Adds Up
• Wedding Budget Breakdown: Plan Your Costs
• US Budget Breakdown by Year: Spending and Revenue

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