Payoff-day interest
Estimate payoff per diem through a target date
A payoff quote is often stated as an amount good through a particular date plus a per-diem amount for each additional day. This calculator works in the opposite direction: start with a principal payoff balance as of a known date, calculate the daily interest, and add that interest through a target payoff date.
How to Calculate Daily Interest on a Loan Payoff
Start with the principal balance used for the payoff and the annual rate that actually accrues interest. Divide the annual rate by the required day-count basis, then multiply by the principal. For the underlying math, see the per diem interest formula.
How to Extend a Payoff Quote by Additional Days
If an existing payoff quote provides a good-through date and a per-diem amount, the arithmetic for a short extension is generally Per diem × Additional days. Follow the creditor's payoff instructions because a new official quote may be required. If a payment, credit, advance, or fee changes the balance, use the Irregular Payment Loan Calculator instead of simply extending the original per diem.
What “per diem” means on a payoff statement
The per-diem figure tells you how much interest is generally added for each additional day while the principal remains unchanged. If a payment or credit posts, the balance can change and the old per-diem amount may no longer be correct.
Why an official payoff may be different
Official payoff statements can include more than principal and interest. Depending on the loan, the amount may include late fees, legal fees, escrow advances, release fees, prepayment charges, unpaid expenses, or credits. Lender rounding and payment-posting rules can also matter.
Use this calculator to check the arithmetic, not replace a payoff quote
The tool is useful for estimating how a payoff changes when the target date moves, checking whether a stated per-diem amount is mathematically reasonable, or planning a private-loan payoff. For a transaction that requires a binding amount, request the official payoff from the creditor or servicer.
Reconciling a loan with irregular activity?
Use Loan Reconciliation & Payoff Pro when you need to reconstruct balances, apply payments or credits, and prepare payoff information. Use Amortization Pro for standard forward-looking schedules.