Bond Equivalent Yield (BEY) Calculator
What is Bond Equivalent Yield (BEY)?
The Bond Equivalent Yield (BEY) is a metric used to calculate the annual yield on a fixed-income security that is sold at a discount and does not pay a coupon (like a Treasury Bill). It allows investors to compare the performance of short-term, zero-coupon investments with conventional bonds that pay semi-annual coupons and use a 365-day year.
Because many short-term instruments are quoted using the Bank Discount Yield (which uses a 360-day year), the BEY is essential for creating an "apples-to-apples" comparison against 365-day benchmarks.
The Bond Equivalent Yield Formula
The calculation for BEY follows this standard formula:
Why BEY Matters
Investors use BEY for three primary reasons:
- Standardization: It converts the yield of a discount bond into an annualized format comparable to Treasury bonds.
- Accuracy: Unlike the Bank Discount Yield, BEY uses the actual purchase price (the amount invested) as the denominator rather than the face value.
- Time Correction: It adjusts for the 365-day calendar year (or 366 in leap years) instead of the 360-day year commonly used in money markets.
Example Calculation
Suppose you purchase a U.S. Treasury Bill with a face value of $1,000 for $985. The bill matures in 180 days.
2. Return on investment = $15 / $985 = 0.015228
3. Annualization factor = 365 / 180 = 2.0277
4. BEY = 0.015228 × 2.0277 = 3.088%
BEY vs. Bank Discount Yield
The Bank Discount Yield (BDY) is often lower than the BEY because BDY uses the face value as the divisor and a 360-day year. In the example above, the BDY would only be 3.00%. The BEY provides a more accurate representation of the investor's actual return on the money they actually spent.