🏧 CD & Fixed Deposit Interest Calculator
Deposit a lump sum for a fixed term and see the interest, tax and the amount you get back at maturity.
Maturity value (after tax)
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How to use
- Choose your currency and enter the amount you'll deposit once at the start.
- Enter the annual interest rate and term. A 6-month CD is 6 months, and a 5-year CD is 60 months.
- Pick simple interest (paid at maturity, typical of Korean time deposits and many fixed deposits) or monthly compound (closer to how many US CDs credit interest).
- Enter a tax rate if you want after-tax numbers: 0% for pre-tax, 15.4% for Korea, or your US marginal bracket.
How CD and fixed deposit interest is calculated
- Simple:
interest = principal × rate × (months ÷ 12) - Monthly compound:
interest = principal × ((1 + rate/12)months − 1) - APY (annual percentage yield) is the compounded annual return:
(1 + rate/12)12 − 1. A 4% rate compounded monthly is a 4.07% APY.
Example: $10,000 at 4% for 1 year
| Method | Interest | Maturity value |
|---|---|---|
| Simple | $400.00 | $10,400.00 |
| Monthly compound | $407.42 | $10,407.42 |
| Simple, after 24% tax | $304.00 | $10,304.00 |
Over short terms the compounding difference is small. Over 5 years it adds up, and the rate matters much more than the method.
Tips
- Deposit insurance: in the US, FDIC (banks) and NCUA (credit unions) cover up to $250,000 per depositor, per institution, per ownership category. In Korea, the Korea Deposit Insurance Corporation (KDIC, 예금보험공사) covers deposits up to its limit per person, per institution. Check the current limit.
- Early withdrawal usually means a penalty (often several months of interest) or a much lower rate, so match the term to when you'll need the money.
- CD ladders: split your money across several terms (for example 1 to 5 years) so part of it matures every year.
- Korea: if total financial income tops ₩20 million a year, it may be taxed under comprehensive income taxation instead of the flat 15.4%.
Actual interest can differ slightly depending on how the bank counts days (actual/365 vs. 30/360) and when interest is credited. This calculator applies tax once at maturity.
FAQ
How much interest will $10,000 earn in a 1-year CD?
At 4% simple interest, $400. With monthly compounding, about $407.42. After a 24% tax bracket, the simple-interest amount drops to $304.
What is the difference between APR and APY on a CD?
The rate (APR) ignores compounding, while APY includes it. With monthly compounding, 4% APR is about 4.07% APY. Compare CDs by APY.
What happens if I withdraw early?
Most CDs and fixed deposits charge an early withdrawal penalty or pay a much lower rate. Check the terms before you open one.
Is my deposit insured?
In the US, FDIC/NCUA insurance covers up to $250,000 per depositor, per institution, per ownership category. Korea’s KDIC also protects deposits up to a set limit per person per bank, and that limit can change.
How much tax do I pay on deposit interest in Korea?
15.4% is withheld at maturity (14% income tax + 1.4% local tax). Some cooperative accounts are 9.5%, and qualifying tax-free accounts are 0%.