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 Actual/360 and Actual/365?

Both conventions count the exact calendar days between dates, but they differ in the assumed year length. Actual/360 uses 360 days as the denominator (common in money markets and some corporate bonds), while Actual/365 uses 365 days (common in UK gilts and some other markets).

How does the 30/360 convention work?

The 30/360 convention assumes each month has exactly 30 days and each year has 360 days. Adjustments are applied when either date falls on the 31st of a month. This convention simplifies calculations and is widely used for US corporate and municipal bonds.

What is a dirty price versus a clean price?

The clean price is the quoted bond price excluding accrued interest. The dirty price (full price) is what the buyer actually pays and equals the clean price plus accrued interest. Settlement in most bond markets uses the dirty price.

Which day count convention should I use?

The convention depends on the bond type and market. US Treasury bonds use Actual/Actual (ISDA). Most US corporate and municipal bonds use 30/360. Eurobonds and money-market instruments often use Actual/360. Always check the bond indenture or term sheet.

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.

How do you calculate accrued interest on a bond?

Accrued interest = face value × annual coupon rate × (days since last coupon ÷ days in the year, per the day count convention). For example, a $1,000 bond at a 5% coupon, 90 days into an Actual/360 period: 1000 × 0.05 × (90 ÷ 360) = $12.50.

Accrued Interest Bond Calculator

Name: Accrued Interest Bond Calculator
Availability: InStock
Author: Nham Vu

Calculate bond accrued interest between coupon dates using Actual/360, Actual/365, or 30/360 day count conventions.

Bond Parameters

Face Value ($)

Annual Coupon Rate (%)

Payment Frequency

Last Coupon Payment Date

Settlement 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

Accrued Interest

$0.00 per $1,000 face value

Coupon per period —

Day count convention —

Accrual fraction —

Convention Comparison

Convention	Days	Period	Accrued Interest

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Summary

Calculate bond accrued interest between coupon dates using Actual/360, Actual/365, or 30/360 day count conventions.

How it works

Enter the bond face value (par value) and annual coupon rate.
Select the payment frequency: annual, semi-annual, or quarterly.
Enter the last coupon payment date and the settlement (value) date.
Choose the day count convention: Actual/360, Actual/365, or 30/360.
The calculator instantly shows accrued days, accrued interest per unit, and total accrued interest.

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

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Last updated: 2026-05-23 · Reviewed by Nham Vu