Late Fee & Overdue Interest Calculator

Calculate daily compounding interest penalties, grace period offsets, and 30/60/90-day aging recovery totals for overdue invoices.

Aging Delinquency Presets

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Delinquency & Penalty Parameters

Original Invoice Principal ($)

Unpaid balance on invoice due date

Days Past Due

days

Elapsed time since payment deadline

Statutory Annual Interest (APR %)

% APR

Standard rate: 10% to 24% per contract/law

Contractual Grace Period

days

Penalty-exempt buffer window

Flat Administrative Late Charge ($)

Fixed fee applied once grace period expires

Current Total Amount Due $5,137.03 Original Principal: $5,000.00

Total Accrued Penalty & Interest +$137.03 Billable Days: 35d (Daily: 0.0493%)

Statutory Late Fee Growth by Aging Bracket

Principal vs. Cumulative Accrual

Compounded Daily Interest:+$87.03

Fixed Administrative Charge:+$50.00

Total Recovery Claim:$5,137.03

Calculator guide

How to use the Late Fee & Interest Calculator

Calculate late payment fees and interest on overdue invoices or balances.

01Set inputsChoose values, units and assumptions.

02Apply the modelDaily rate = Annual rate ÷ 365. With daily compounding, interest = Principal × ((1 + daily rate)^overdue days − 1).

03Read the resultCheck the output against the assumptions before using it.

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What this calculator does

The calculator removes any grace period, applies the selected annual rate to the billable overdue days and adds a flat late fee when applicable. It also projects penalty amounts at 30, 60 and 90 days.

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Formula & method

Daily rate = Annual rate ÷ 365. With daily compounding, interest = Principal × ((1 + daily rate)^overdue days − 1).

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Assumptions & notes

Late-fee and interest rules vary by contract and jurisdiction.
Daily compounding is a modeling assumption and may not match the governing agreement.
Use the result as an estimate and verify the applicable legal or contractual terms.