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Irregular Payment Loan Calculator

Rebuild a real-world loan history with exact transaction dates. Add partial payments, late payments, principal-only payments, fees, credits, and additional advances, then see how every transaction changes accrued interest and principal.

Your calculated results

The sample values calculate automatically. Change any input to evaluate your own scenario.

Mathematical estimate only. Loan contracts can use different day-count, compounding, late-fee, capitalization, grace-period, payment-allocation, and rounding rules. Verify legal or contractual payoff figures against the governing documents.

Why this calculator is different

Reconcile the loan in the order events actually happened

Ordinary amortization calculators assume every payment arrives on schedule. Real loans often do not. A late payment changes the number of interest-accrual days, a principal-only payment changes every later per-diem amount, and an advance raises the balance that earns interest.

This calculator processes each dated transaction in chronological order. Before applying a transaction, it first accrues simple daily interest on the principal that was outstanding during that interval.

Interest for interval = Principal × Annual Rate × Days ÷ Day-Count Basis

The 365-day basis is common for actual-day calculations. Some notes instead use a 360-day convention. Use the convention stated in the loan documents.

Payment application matters

The calculator can apply ordinary payments to accrued interest before fees, or fees before accrued interest, with the remainder going to principal. Principal-only payments bypass accrued interest and fees. That distinction can materially change the running balance.

Need to save and document a real reconciliation?

Loan Reconciliation & Payoff Pro is designed for more detailed payment-history work, while Amortization Pro creates complete scheduled amortization tables.

Frequently asked questions

How does the calculator accrue interest?

It accrues simple daily interest on outstanding principal for the actual number of calendar days between transaction dates, using the selected 360- or 365-day basis.

How are regular payments applied?

You can choose whether a payment is applied to accrued interest before fees or to fees before accrued interest. Any remainder then reduces principal.

Does unpaid interest compound?

No. This calculator keeps unpaid accrued interest separate from principal unless you explicitly enter a principal advance. Many contracts use different rules, so compare the result with the governing note.

Can I calculate a payoff through a future date?

Yes. Choose a calculate-through date after the last transaction. The calculator accrues additional daily interest through that date and shows an estimated payoff.