債券計算ツール
The detailed guide below is currently available in English.
How bond prices are determined
A bond is worth the present value of everything it will pay: each annual coupon plus the face value returned at maturity, each discounted at today's market rate:
Price = C × [1 − (1 + y)−n] / y + F × (1 + y)−n
When the market rate rises above the coupon, the discounted value falls below par (a discount); when it falls below the coupon, the price rises above par (a premium). Longer terms amplify both effects.
よくある質問
Why does my bond trade below face value?
Because newer bonds pay more than its coupon. Discounting older, smaller coupons at the higher market rate produces a price under par, which compensates the buyer until yield to maturity matches the market.
What is current yield vs. yield to maturity?
Current yield is just the annual coupon divided by today’s price. Yield to maturity also counts the gain (or loss) when the bond redeems at par, so it is the more complete return measure — and it equals the market rate you enter when the price is fair.