About Coupon Beacon
Small, free calculators for the arithmetic of bonds and Treasury bills.
What it is
Coupon Beacon answers the questions that come up when reading a bond quote or a bill auction result: what yield does this price imply, what price does this yield imply, how much income does the coupon pay for the price, how do a bill's three yields relate, and when does each coupon arrive. Every page shows its formula and names the source behind it, such as the U.S. Treasury's rules in 31 CFR Part 356, the MSRB's Rule G-33 and Investor.gov.
Educational use only
It is educational and not financial advice. The calculators work out the numbers you enter; they do not recommend any bond, bill, fund or provider, and the example rates are there to be changed, not forecasts or market quotes. A yield is only as good as its assumptions: it says nothing about whether an issuer will pay. Coupon Beacon is not a bank, broker or government site and has no link to any of them. For a real purchase, the security's official documents and your trade confirmation are the figures that count.
How it works
Everything runs in your browser. The formulas are part of the page, so nothing you type is sent anywhere, and once a page has loaded it keeps working without a connection. There are no accounts, cookies or ads.
Check our working
The calculators are tested against published worked examples: the Treasury's own price and bill examples in 31 CFR Part 356 Appendix B, TreasuryDirect's bill example, and the examples in Microsoft's documentation for the spreadsheet PRICE, YIELD and MDURATION functions. Each page lists its sources, linked, so you can compare.