Google Sheets Accrued Interest Payment Calculator

To calculate an accrued interest payment in Google Sheets, enter the principal, annual interest rate, and number of days accrued, then apply the appropriate day-count convention. The calculator below estimates simple interest for a period; it does not determine a lender’s exact payment or account for compounding, fees, or contract-specific rules.

Formula

The simple-interest formula is interest = principal × annual rate × accrued days ÷ days per year. Written using the calculator’s inputs, it is I = P × (APR ÷ 100) × d ÷ B.

• I is accrued interest in dollars.
• P is the principal in dollars.
• APR is the annual rate entered as a percentage, such as 6 for 6%.
• d is the number of days in the accrual period.
• B is the annual day-count basis. Common conventions use 360 or 365 days; the applicable agreement or calculation policy determines which to use.

The second output adds this estimated interest to principal. It represents a combined amount only if the interest is being settled alongside the principal; many ordinary periodic payments do not repay all principal at once.

Worked Example

With the defaults—$10,000 principal, 6% annual interest, 30 accrued days, and a 365-day basis—the calculation is:

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

Assumptions

• The rate and principal stay fixed during the accrual period.
• Interest accrues as simple interest, not interest-on-interest.
• The day-count basis is the number entered; the example uses 365.
• The calculation does not include fees, taxes, payment allocation, late charges, or other contract terms.

How Accrued Interest Works

Accrued interest is interest that has built up over time but has not yet been paid. It may appear between scheduled payment dates, when a balance is settled, or in financial records where interest is recognized as it is earned. The meaning of “payment” depends on context: it could refer to paying the accrued amount alone, adding it to a regular installment, or settling accrued interest together with principal.

For a loan with a simple daily accrual method, a balance commonly earns a fraction of its annual interest for each day. The formula estimates that fraction by multiplying the annual rate by days accrued and dividing by the chosen annual basis. A change in principal, rate, or day count changes the result. If interest compounds or the rate varies, this simple calculation may not match the amount due.

A related misconception is that APR alone always specifies exactly how daily interest is calculated. It does not necessarily provide all the details needed: the agreement may define a day-count method, payment application, compounding, and the dates that count. Use the contractual method for an actual payment amount.

Using the Calculator in Google Sheets

The calculator provides the arithmetic without requiring spreadsheet syntax. To reproduce it in Google Sheets, place principal in A2, APR as a percentage in B2, accrued days in C2, and the day-count basis in D2. If B2 contains a percent-formatted value such as 6%, use:

• =A2*B2*C2/D2 to calculate interest.
• =A2+(A2*B2*C2/D2) to calculate principal plus interest.

Format the output cells as currency and choose two decimal places for display. In this setup, entering 6% in B2 means Sheets stores the rate as 0.06. If you enter the number 6 instead, use =A2*(B2/100)*C2/D2 so the percentage is converted correctly. Mixing these two conventions can make the result 100 times too large.

Keep the day-count basis in a separate cell rather than typing it into the formula. That makes it easier to see whether a calculation uses 360, 365, or another stated convention. Check that the date range and the number of days match the agreement’s counting rule; whether the first or last day is included can matter.

Day-Count Choices and Limits

A 365-day basis divides annual interest into 365 equal daily portions for this estimate. A 360-day basis divides it into 360 portions, so using 360 rather than 365 produces a larger result for the same principal, rate, and number of days. Some instruments or accounting methods use more detailed conventions that treat months or years differently. The basis should come from the relevant contract or calculation instructions, not from an assumption that one convention always applies.

This calculator allows a basis from 1 through 366 as a mathematical input range, but that does not mean each value is an appropriate convention. Select the basis required for the situation. Leap-year treatment may also be specified separately in some agreements; a single fixed denominator might not reproduce that method.

The formula assumes the principal does not change during the period. If payments, withdrawals, rate resets, or capitalization occur, divide the timeline into segments and calculate each segment using its own balance, rate, days, and basis, then add the interest amounts. For compounding, calculate interest on the changing balance according to the specified schedule rather than applying this one-period simple-interest formula.

Common Errors and Checks

• Entering 6 instead of 6%: confirm whether your rate cell is percentage-formatted or a whole number.
• Using the wrong day count: verify the basis and date-counting method before treating the result as an amount due.
• Rounding too early: retain full precision in intermediate calculations and round the final displayed amount to cents, unless the agreement specifies another method.
• Confusing accrued interest with a payment: interest alone is not necessarily the full installment or payoff amount.
• Ignoring balance changes: if principal changes during the period, calculate separate intervals rather than applying one balance to all days.

A useful check is to confirm that interest rises when principal, rate, or elapsed days rise, and falls when the day-count denominator rises. At zero accrued days, the simple-interest result should be zero.

Frequently Asked Questions

How do I calculate accrued interest in Google Sheets?
For a simple-interest estimate, multiply principal by the annual rate as a decimal and by accrued days, then divide by the chosen day-count basis. For a percent-formatted rate cell, the formula is =principal*rate*days/basis.

Should I use 360 or 365 days?
Use the day-count convention specified for the loan, security, or accounting calculation. The choice affects the result, so do not substitute one basis for another without checking the applicable instructions.

Is accrued interest the same as a monthly payment?
No. Accrued interest is the interest accumulated over a period. A scheduled payment may include interest and principal, and its allocation depends on the payment terms.

Does this formula include compound interest?
No. It estimates simple interest on a fixed principal. If interest compounds or the balance changes, use the applicable schedule or calculate separate periods using the changing balance.

Why does my Google Sheets result look 100 times too high?
You may have entered a whole-number rate, such as 6, while using a formula that expects 6% stored as 0.06. Either format the cell as a percentage or divide the whole-number rate by 100 in the formula.

This calculation is an educational estimate; the lender’s disclosure or account statement provides the exact figures applicable to a payment.

Related

• Accrued Interest Expense Normal Balance Explained
• Accrued Interest Expense Entry: Journal Entry and Example
• Accrued Interest Expense Journal Entry Explained

in p | Principal | $ | 10000 | 0 | 100000000
in apr | Annual interest rate | % | 6 | 0.01 | 100
in days | Days accrued | days | 30 | 0 | 3660
in basis | Days per year | days | 365 | 1 | 366
out interest | Accrued interest | $ | p * (apr / 100) * days / basis | 2
out total | Principal plus accrued interest | $ | p + interest | 2