What is accrued interest on a bond?
Accrued interest is coupon interest that accumulates between scheduled payments. When a bond is traded between coupon dates, a buyer may owe the seller accrued interest at settlement; the exact amount depends on the bond’s terms, day-count method, and transaction dates. FINRA describes this in its Accrued Interest Calculator and provides separate conventions for corporate and municipal bonds versus government bonds.
How is accrued interest estimated?
This calculator applies a simple annual-coupon model: par value × annual coupon rate × accrued days ÷ denominator. For example, with $1,000 par, a 5% annual coupon, 90 accrued days, and a 360-day denominator, the estimate is $12.50. This is an illustration of the entered formula, not a market quote. Select 360 or 365 only if that basis fits the bond; a custom denominator is available for other stated conventions.
Enter the aggregate par value of bonds with identical terms, rather than their current market price. Enter the annual coupon rate, not the yield to maturity. The day count is entered directly so you can follow the applicable issue terms or settlement convention. If the next coupon date, last coupon date, settlement date, or an irregular first period affects the count, verify those dates against the trade confirmation and offering documents.
Source and date: FINRA’s accrued-interest calculator (accessed 2026-11-03) states that its corporate and municipal bond calculation uses a 360-day year, while its government bond calculation uses a 365-day year. The result here uses that disclosed basis distinction as an input-driven illustration. FINRA’s calculator also cautions users to enter par value and coupon rate and to group only bonds with identical attributes.
Actual market conventions and bond documentation control. This page does not determine a contractual settlement amount and does not model date-specific day-count rules, coupon schedules, leap-year details, accrued interest adjustments, taxes, commissions, or other charges. Government securities can have their own calculation rules; do not assume the example basis applies to every security. For a transaction, compare the broker’s accrued-interest figure with the issue terms and trade confirmation.
This educational calculator is not a recommendation to buy or sell a bond and is not financial, tax, or legal advice.
Frequently asked questions
Should I enter par value or market price?
Enter aggregate par value for the modeled bonds. FINRA’s calculator specifies par value rather than current purchase price for its accrued-interest calculation.
Is the coupon rate the same as yield to maturity?
No. The coupon rate is the stated annual interest rate applied to par. Yield to maturity also reflects price, scheduled cash flows, and time to maturity. Use the coupon rate here.
Which day-count basis should I select?
FINRA uses 360 days for its corporate and municipal examples and 365 days for government bonds. Verify the actual security convention and settlement dates; this tool cannot identify them from a ticker or CUSIP.
Does this give the exact amount due at settlement?
No. It is a simple estimate using the terms and day count you enter. The bond’s documents, market convention, settlement date, and broker calculation determine a transaction amount.