What is accrued interest on a bond?

Accrued interest is the interest that has accumulated on a bond since its last coupon payment date. When a bond is traded between coupon dates, the buyer compensates the seller for this earned-but-unpaid interest by paying the dirty price (clean price + accrued interest).

What is the difference between clean price and dirty price?

The clean price is the market quote expressed as a percentage of par or dollar amount excluding accrued interest. The dirty price (or settlement/invoice price) is the total cash paid by the buyer to the seller, equal to the clean dollar price plus accrued interest.

How does Actual/Actual ICMA work for US Treasuries?

US Treasury notes and bonds use the Actual/Actual ICMA convention for regular coupon periods (31 CFR Part 356). It calculates the exact number of calendar days from the last coupon date to settlement divided by the exact number of calendar days in the full coupon period between the last and next coupon dates.

How does the US 30/360 Bond Basis convention work?

The US 30/360 convention assumes 30 days per month and 360 days per year. It applies specific end-of-month adjustments: if the last coupon date falls on the 31st or the last day of February, it is adjusted to day 30, and similar rules apply to settlement to maintain a 30-day month uniform basis.

Which convention is used for corporate and municipal bonds?

In the United States, municipal bonds (per MSRB rules) and corporate bonds standardly trade on a 30/360 day count basis. Eurobonds and commercial paper commonly use Actual/360 or Actual/365 Fixed.

Is the settlement date the same as the trade date?

No. The settlement date is when the transaction actually settles (cash and bonds change hands), typically T+1 or T+2 after the trade date. Accrued interest is calculated to the settlement date, not the trade date.

What happens if settlement occurs on a coupon payment date?

If a bond settles on the coupon payment date, the accrued interest is $0.00. The seller receives the full coupon payment directly from the issuer, and the dirty price equals the clean price.

Accrued Interest Bond Calculator

Calculate bond accrued interest, clean price, and dirty price across Actual/Actual ICMA, US 30/360, Actual/360, and Actual/365 conventions.

Bond Parameters

Face Value ($)

Annual Coupon Rate (%)

Clean Price Quote (% of Par)

Payment Frequency

Last Coupon Payment Date

Settlement Date

Next Coupon Payment Date

Day Count Convention

Fill in the parameters and click
Calculate Accrued Interest

Accrued Days

—

days since last coupon

Period Length

—

days in coupon period

Clean Price ($)

$0.00

Quote: 100.00% of par

Dirty / Settlement Price

$0.00

Invoice: 100.00% of par

Accrued Interest

$0.00 per $1,000 face value

Day count convention —

Coupon per period —

Accrued clean dollar —

Total dirty settlement —

Accrual fraction —

Convention Comparison

Actual/Actual ICMA uses exact days in the regular coupon period. Corporate & municipal bonds typically use US 30/360.
Convention	Days	Period	Accrued Int.	Dirty Price

Regular coupon periods only. Check the security documents for odd first or final coupons, ex-coupon rules, fees, taxes, and the contractual day-count convention.

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Summary

Calculate bond accrued interest, clean price, and dirty price across Actual/Actual ICMA, US 30/360, Actual/360, and Actual/365 conventions.

How it works

Enter the bond face value (par value), annual coupon rate, and clean price quote (% of par).
Select the payment frequency: annual, semi-annual, or quarterly.
Enter the last coupon payment date, settlement date, and next coupon payment date.
Choose the day count convention: Actual/Actual ICMA (Treasury standard), US 30/360 (Corporate/Muni), Actual/360, or Actual/365 Fixed.
The calculator displays accrued interest, clean dollar value, dirty settlement invoice price, and a cross-convention comparison table.

Use cases

Price bonds being bought or sold between coupon payment dates.
Reconcile bond settlement amounts on trade confirmation.
Verify accrued interest figures reported by brokers or custodians.
Compare accrued interest under different day count conventions.
Calculate clean price from dirty price (or vice versa).
Support fixed income portfolio accounting and valuation.
Teach bond math and day count conventions in finance courses.
Audit coupon accrual entries in accounting systems.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu