Accrued Interest Example and Calculator

An accrued interest example shows how much interest has built up on a loan or investment over a period but has not yet been paid. Enter the principal, annual interest rate, and elapsed days to estimate simple accrued interest and the resulting amount owed or earned.

Formula

This calculator uses simple interest on an actual-days/365 basis:

Accrued interest = principal × annual rate × days accrued ÷ 365

• Principal (p) is the amount on which interest is calculated, in dollars.
• Annual interest rate (apr) is entered as a percentage, such as 6 for 6% per year. The formula converts it to a decimal by dividing by 100.
• Days accrued is the number of days in the period.
• Accrued interest is the estimated interest for that period, in dollars.

The second output adds accrued interest to principal for illustration. It is not necessarily a payoff quote: an actual amount due can also depend on payment dates, compounding, fees, contractual day-count rules, and other account terms.

Worked Example

Using the calculator’s default values—$10,000 principal, a 6% annual rate, and 30 days—the calculation is:

1. Convert the rate to decimal form: 6 ÷ 100 = 0.06.
2. Multiply principal by the annual rate: $10,000 × 0.06 = $600 per year.
3. Scale that annual amount to 30 days: $600 × 30 ÷ 365 = $49.315…
4. Round to cents: accrued interest is $49.32.
5. Add it to principal: $10,000 + $49.32 = $10,049.32.

The result assumes a 365-day year and simple interest. The amount calculated before rounding is about $49.315; displaying currency to cents produces $49.32.

Assumptions

• The rate remains fixed during the entered period.
• The calculation uses simple interest; it does not add interest to principal during the period.
• Days are counted on an actual-days/365 basis. Some agreements or investments use a different day-count convention, including a 360-day denominator or a calendar-year basis.
• No payments, fees, taxes, or other account adjustments are included.

What Accrued Interest Means

Interest is the cost of borrowing money or the return earned for lending or depositing it. It accrues as time passes, even when the payment or posting date comes later. For example, a loan may accumulate interest every day while requiring a monthly payment; the statement records or collects the accumulated amount according to the agreement’s schedule.

Accrued interest is therefore a timing concept. It describes interest associated with a period, not necessarily interest already charged to an account or paid in cash. On a borrower’s records, it may represent interest owed but not yet paid. For an investor, it can represent interest earned since the last payment or settlement date.

The amount does not always increase the principal used to calculate the next day’s interest. Under simple interest, it is calculated from the original principal. Under compounding, unpaid interest may become part of the balance on specified dates, so later interest can be calculated on a larger amount. The contract or investment terms determine how that works.

How to Use the Estimate

• Enter the principal or balance that actually earns or incurs interest.
• Use the annual rate as a percentage, not a decimal: enter 6 for 6%, not 0.06.
• Count the days in the relevant period, using the start and end dates required by the account’s terms.
• Compare the result with a statement, transaction confirmation, or agreement that specifies the applicable calculation method.

This estimate is useful for understanding the scale of interest between two dates, checking a rough calculation, or seeing how principal, rate, and time affect the amount. It should not be treated as a lender’s payoff figure or a guaranteed investment return. If the balance changes because of payments or additional borrowing, one calculation using a single principal may not represent the entire period.

Day-Count Methods and Compounding

The denominator in an interest calculation matters. This calculator divides by 365, which is a common illustrative convention for actual days, but financial products can define accrual differently. A 360-day convention calculates a somewhat larger daily fraction for the same annual rate and number of days. Some methods use 366 in a leap year, while others use a fixed contractual basis. The relevant disclosure or agreement is the source for the method that applies.

Compounding is a separate issue. With simple interest, the same principal is used throughout the period. With daily compounding, interest may be added to the balance at regular intervals, and subsequent interest can be calculated on that updated balance. Monthly compounding follows a different schedule. Do not assume that an annual rate alone tells you exactly how interest accrues or when it is posted.

Common Errors and Limits

• Mixing percentage formats: entering 0.06 when the input expects 6 means 0.06%, not 6%.
• Using the wrong balance: principal should reflect the amount subject to interest during the period. A changing balance may require splitting the period into segments.
• Miscounting days: payment posting dates and whether the first or last day counts can affect the result.
• Ignoring terms: compounding, a 360-day basis, variable rates, and payment timing can make an account’s figure differ from this simple estimate.
• Rounding too early: keep precision during intermediate steps and round the displayed money result to cents.

The calculator is not designed for amortizing loans with regular payments, changing rates, or daily balance changes. Those require a schedule that accounts for each payment and balance update. It also does not determine whether interest is legally due, how an account must be reported, or the tax treatment of interest.

Frequently Asked Questions

How do you calculate accrued interest?
For simple interest, multiply principal by the annual rate expressed as a decimal and by the fraction of a year elapsed. This example uses days ÷ 365 for that fraction.

Is accrued interest the same as interest paid?
No. Accrued interest has accumulated over time, but it may not yet have been paid or posted. Whether it is added to a balance or paid on a particular date depends on the account terms.

Does accrued interest compound?
Not necessarily. Simple-interest calculations do not compound during the period. An account that compounds adds interest to its balance on a schedule, which can cause later interest to be calculated on interest already added.

Why does my statement show a different amount?
The statement may use another day-count basis, compounding schedule, rate, balance, or start and end dates. Payments, balance changes, and rounding rules can also affect the figure.

Is accrued interest included in a loan payoff amount?
A payoff amount may include interest accrued through a specified date, but it can also account for other contract-specific amounts. Use the figure supplied for the relevant date rather than treating this estimate as a payoff quote.

This result is an estimate for educational use; the lender’s disclosure gives the exact figures.

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in p | Principal | $ | 10000 | 0 | 100000000
in apr | Annual interest rate | % | 6 | 0.01 | 100
in days | Days accrued | days | 30 | 0 | 365
out interest | Accrued interest | $ | p * (apr / 100) * days / 365 | 2
out total | Principal plus accrued interest | $ | p + interest | 2