Bond Yield Calculator

Estimate the after-tax return on a bond — coupon, compound, simple-interest, or zero-coupon — in KRW, USD, EUR, JPY, GBP, or CNY, including interest income tax and trading fees, for either holding to maturity or selling early, with the full cash-flow schedule.

How to use Bond Yield Calculator

1. New here? Pick one of the examples under "Load an example" — every field is filled in and the result appears at once, ready for you to edit.
2. Pick the currency (Korean won by default in Korean, US dollars otherwise) and the bond type: coupon, compound, simple, or zero-coupon.
3. Choose how you enter the amounts: "face value + price" when you know both, or "amount + yield" when your broker only shows what you invest and the yield.
4. In "amount + yield" mode the price that produces the pre-tax yield you typed is solved for, and the face value follows. By default the purchase fee comes out of the amount you typed, so slightly less is spent on the bond itself. Prices are quoted per 10,000 of face for won bonds and per 100 for every other currency.
5. Enter the coupon rate, purchase date, and maturity date — type dates directly (2029-01-01) or press the calendar button to pick them. Set the coupon frequency yourself, or type the remaining number of payments ("48") and the frequency is derived. Compound and simple bonds also need the issue date so interest accrues correctly.
6. Choose whether you hold to maturity or sell early; for an early sale, add the sale date and expected price.
7. Add the purchase and sale fees and the interest income tax. Each field has a Rate/Amount switch, so you can type the actual amount instead of a percentage. You then get after-tax proceeds, the after-tax annual yield, and the deposit-equivalent rate.
8. Read the cash-flow table below to see what arrives on each coupon date and how much tax is withheld.

Frequently asked questions

How much tax is withheld on bond interest in Korea?

15.4% — 14% income tax plus 1.4% local tax. If your total financial income exceeds 20 million KRW a year it is rolled into comprehensive taxation, which can raise the effective burden.

What if I know the fee or tax as an amount, not a percentage?

Use the Rate/Amount switch above each field. You can type the figure straight off your trade confirmation, and flipping back converts it to the equivalent rate. A tax amount is split across the coupon dates in proportion to what each one is taxed on, and the effective rate it works out to is shown alongside.

Are capital gains on bonds taxed?

For individuals in Korea they generally are not, so the calculator leaves them untaxed by default. The discount on a zero-coupon bond counts as interest and is always taxed. Turn the option on to compare a taxed case.

Why does a low-coupon bond show a high yield?

Buying below par (a price under 10,000) adds the pull to par at maturity. That gain is usually untaxed, so a cheap low-coupon bond often wins on an after-tax basis.

Can I work from "48 payments, 1.25% coupon, 8.58% yield" alone?

Yes. Enter the maturity date and 48 payments to derive the frequency, then switch to "amount + yield", type what you plan to invest and 8.58%, and the implied price and face value are solved for. Check whether your broker quotes that yield before or after tax — the result shows pre-tax, after-tax, and deposit-equivalent side by side so you can tell which one matches.

What is the deposit-equivalent rate?

The after-tax annual yield converted back into the pre-tax rate a bank deposit would need to match it, so you can compare it with deposit rates directly.

Why does the pre-tax annual yield differ from the coupon rate?

The coupon rate applies to face value, while the annual yield is an internal rate of return on what you actually paid and when each payment arrives, so the purchase price and coupon frequency both move it.

Is accrued interest included?

No — the calculator assumes accrued interest is already inside the purchase price. If your trade settles accrued interest separately, the real return will differ slightly.

Can I use it for dollar bonds?

Yes. Switch the currency to USD, EUR, JPY, GBP, or CNY and every amount is shown in it, with prices quoted per 100 of face value as is standard outside Korea. FX moves are not modelled, so read the result as a return in that currency.

Does changing the currency change the tax rate?

No — tax depends on where you are resident, not on the currency. The 15.4% default is the Korean withholding rate, so set your own rate for bonds taxed elsewhere.