Bond Accrued Interest Calculator

Accrued coupon interest and dirty price with 30/360, ACT/365, ACT/360, or ACT/ACT day counts.

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Educational estimate only — not investment, lending, or financial advice. Confirm figures with statements or a qualified professional before you act.

About this tool

Enter the previous and next coupon dates, a settlement date, the coupon and a day-count convention. The calculator returns the interest the seller has earned since the last coupon and, with a clean price, the dirty price the buyer pays.

How to use

1
Step 1
Enter face value, coupon rate and coupons per year.
2
Step 2
Enter the previous coupon date, the settlement date and the next coupon date.
3
Step 3
Choose a day-count convention and optionally a clean price.
4
Step 4
Press Calculate.

How it works

Accrued interest is the coupon payment times the fraction of the coupon period that has passed. The fraction is days since the last coupon divided by days in the period, counted under your convention. The 30/360 convention treats every month as 30 days; the actual conventions count real calendar days. The dirty price is the clean price plus accrued interest.

accrued = (face × coupon rate ÷ frequency) × (days since last coupon ÷ days in coupon period)      dirty price = clean price + accrued

Worked example

Settling six weeks after a coupon

Input
Face 1,000; coupon 6%; 2 a year; previous 2024-01-15; settlement 2024-03-01; next 2024-07-15; clean 980
Output
30/360: 7.67, dirty price 987.67. Actual days: 7.58, dirty 987.58
Walkthrough
Each coupon is 30. Under 30/360 the elapsed time is 46 days of a 180-day period: 30 × 46 ÷ 180 = 7.67. Counting real days, 46 of 182: 30 × 46 ÷ 182 = 7.58. At the sample dates of 15 January, 15 April and 15 July 2024, both give 15.00.

Limitations

  • Settlement must fall between the two coupon dates.
  • Does not value the bond; use the Bond Calculator for price and yield.

Questions

What is accrued interest on a bond?
The part of the next coupon that the seller has earned between the last coupon date and settlement.
What is the difference between clean and dirty price?
The clean price excludes accrued interest; the dirty price, which the buyer actually pays, includes it.
What is 30/360?
A day-count convention that treats every month as 30 days and the year as 360.
Which convention should I use?
The one stated in the bond's terms or your market's convention. The choice changes the result by small amounts, such as 7.67 against 7.58.

Features

  • 30/360 and actual day counts
  • Clean and dirty price
  • Runs in your browser

Related resources

Guides and videos from around the web—opens on YouTube or the publisher’s site.

  • Calculating simple and compound interest

    Khan Academy

    Worked examples to compare with calculator output.

    Watch on YouTube

  • Introduction to interest

    Khan Academy

    Simple vs compound framing for NOM/EFF conversions.

    Watch on YouTube

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