Bond Accrued Interest Calculator
Created by: Lucas Grant
Last updated:
Estimate coupon accrual between payment dates and translate quoted clean price into dirty price for a simple bond settlement scenario.
Bond Accrued Interest Calculator
FinanceEstimate accrued interest and dirty price from coupon terms and where the trade falls inside the current coupon period.
What is a Bond Accrued Interest Calculator?
A bond accrued interest calculator estimates how much of the next coupon payment has already been earned between the last coupon date and the settlement date.
It helps bridge the gap between the quoted clean price and the actual dirty price that changes hands.
This matters because bonds are often quoted without accrued interest even though the buyer typically compensates the seller for coupon income already earned.
Without that adjustment, settlement cash can look lower than it really is.
A practical accrued-interest tool should show coupon earned to date, dirty price, elapsed percentage of the coupon period, and the days still remaining until the next coupon payment.
How the Accrued Interest Calculation Works
The calculator first determines the coupon payment for one period using face value, coupon rate, and payment frequency.
It then multiplies that coupon amount by the fraction of the coupon period that has already elapsed based on the day inputs you provide.
Accrued interest is added to the clean price to estimate dirty price.
This is a useful settlement approximation, although actual bond-market conventions can vary by instrument and day-count method.
Core accrued-interest relationships
Coupon per period = face value x coupon rate / payments per year
Accrued interest = coupon per period x days since last coupon / days in coupon period
Dirty price = clean price + accrued interest
Example Scenarios
Example 1: Mid-period settlement
If a bond settles halfway through the coupon period, accrued interest is roughly half of that period's coupon payment.
Example 2: Just before coupon date
Dirty price rises as more of the coupon period passes because more interest has been earned by the seller.
Example 3: Trade review
Operations and portfolio teams can use the estimate to explain why settlement cash differs from the quoted screen price.
How People Use This Calculator
- Translate clean price quotes into approximate settlement cash requirements.
- Estimate how much coupon income the seller has already earned before purchase.
- Review bond trade confirmations and settlement assumptions.
- Teach the distinction between market quotation and actual money exchanged.
Tips for Better Accrued Interest Estimates
Match the bond's coupon frequency and period length as closely as possible.
The more your day inputs resemble the actual settlement convention, the more useful the estimate will be.
Remember that this calculator is intentionally simplified.
For production trade settlement, specific day-count conventions, ex-coupon rules, and holiday calendars can still change the final number.
Frequently Asked Questions
What is accrued interest?
Accrued interest is the portion of the next coupon payment that has already been earned since the last coupon date.
What is the difference between clean and dirty price?
Clean price excludes accrued interest, while dirty price includes the quoted price plus the accrued coupon amount.
Why does settlement timing matter?
The buyer typically reimburses the seller for coupon income already earned during the current coupon period.
Does this handle every day-count convention?
No. It is a simplified planning tool based on the days and coupon period inputs you provide.
Sources and References
- Fixed-income references covering clean price, dirty price, and accrued interest concepts.
- Investor education material explaining bond settlement and coupon-period timing.
Planning Note
Bond Accrued Interest Calculator is a planning estimate. Live bond prices can differ because of settlement timing, call provisions, credit spreads, taxes, and market liquidity.