CalKit Guides

What Are Loan Repayment Methods?

When you take out a loan, you must choose how to repay the principal and interest. The repayment method significantly affects your monthly payments and total interest burden, so it is important to select the method that fits your financial situation.

Comparing Three Repayment Methods

• Equal Payment (Annuity): You pay the same total amount (principal + interest) each month. Budgeting is easy, but interest makes up a larger share early on, and total interest is higher than equal principal.
• Equal Principal: You repay the same principal amount monthly, and interest decreases as the balance shrinks. Initial payments are higher, but total interest is lower over time.
• Bullet Repayment: You pay only interest during the loan term and repay the full principal at maturity. Monthly burden is lowest, but total interest is the highest.

Which Method Is Right for You?

Choose equal payment for predictable monthly expenses, equal principal to minimize total interest, or bullet repayment for short-term cash flow flexibility. Use CalKit's loan calculator to compare repayment schedules side by side.

The Gap Between Salary and Take-Home Pay

The amount on your employment contract and the amount deposited into your bank account are quite different. Each month, income tax, local income tax, national pension, health insurance, long-term care insurance, and employment insurance are withheld from your paycheck.

Key Deduction Items

• National Pension: Employees contribute 4.5% of monthly salary.
• Health Insurance: About 3.545% of monthly salary, plus long-term care insurance at 12.81% of health insurance.
• Employment Insurance: 0.9% of monthly salary.
• Income Tax: Progressive rates from 6% to 45% apply based on taxable income brackets.
• Local Income Tax: An additional 10% of income tax is levied.

Take-Home Pay Tips

For an annual salary of 50 million KRW, take-home pay is roughly 35-37 million KRW. It varies depending on the number of dependents and non-taxable items (such as meal allowances). Use CalKit's salary calculator for an accurate estimate.

Types of Real Estate Taxes

Different taxes apply when acquiring, holding, and selling real estate. Understanding the tax burden in advance is crucial when investing in property or buying your home.

Taxes by Stage

• Acquisition - Acquisition Tax: Paid when purchasing property. For housing, rates of 1-3% apply, with higher rates (8-12%) for multiple homeowners.
• Holding - Property Tax: Paid annually in July and September. Rates of 0.1-0.4% are applied based on the officially assessed value.
• Holding - Comprehensive Property Tax: A holding tax levied when the combined assessed value exceeds a certain threshold. Progressive rates from 0.6% to 6% apply.
• Disposal - Capital Gains Tax: Tax on profits when selling property. Rates of 6-45% apply based on holding period and number of homes, with potential surcharges.

Tax Saving Tips

You can significantly reduce your tax burden by meeting the 1-household-1-home tax exemption requirements (2-year holding, 2-year residence in regulated areas) and utilizing long-term holding special deductions. Check your estimated taxes with CalKit's real estate tax calculators.

BMI (Body Mass Index)

BMI is calculated by dividing weight (kg) by height (m) squared. According to the Korean Society for the Study of Obesity, below 18.5 is underweight, 18.5-22.9 is normal, 23-24.9 is overweight, and 25 or above is obese. However, BMI does not account for muscle mass, so it is best reviewed alongside body fat percentage.

BMR (Basal Metabolic Rate)

BMR is the minimum energy required to sustain life. It is calculated using the Harris-Benedict or Mifflin-St Jeor equations. It varies by age, sex, weight, and height. When dieting, consuming below your BMR can trigger yo-yo effects, so caution is advised.

Body Fat Percentage

Body fat percentage is the ratio of fat to total body weight. Normal ranges are 10-20% for men and 18-28% for women. High body fat increases the risk of various lifestyle diseases.

Using Health Metrics Effectively

By checking all three indicators together, you can get a comprehensive view of your body composition and health status. Measure yours now with CalKit's health calculators.

Income Tax Basics

Income tax is levied on an individual's earned income. Korea uses a progressive tax structure with rates ranging from 6% (up to 14 million KRW) to 45% (over 1 billion KRW). Deduction items differ by income type, including employment income, business income, and freelancer income.

Value-Added Tax (VAT)

VAT is a tax on the value added during transactions of goods or services. Korea's standard rate is 10%. Businesses pay by deducting input tax from output tax. Tax-exempt businesses are not required to pay VAT.

Capital Gains Tax

This tax is imposed on profits from the transfer of assets such as real estate and stocks. Base rates follow the same 6-45% progressive structure as income tax. Higher rates apply for short-term holdings or multiple homeowners. Long-term holding special deductions can reduce taxes as the holding period increases.

The First Step to Tax Savings

Understanding the basic principles of tax calculation is the starting point for tax savings. Use CalKit's various tax calculators to estimate your tax burden and prepare in advance.

Metric and Imperial Systems

Korea officially uses the metric system (SI units), but imperial units are frequently encountered in daily life. Inches (2.54 cm), feet (30.48 cm), pounds (0.4536 kg), and ounces (28.35 g) are commonly used for electronics and overseas shopping.

Traditional Korean Units

• Pyeong (坪): The most commonly used area unit in real estate. 1 pyeong = approximately 3.3058 m². Although m² is legally required, pyeong is still widely used in everyday life.
• Geun (斤): A weight unit for meat and fruit. 1 geun = 600 g.
• Doe/Mal: Used for measuring grains. 1 doe = approximately 1.8 L, 1 mal = 18 L.

Temperature Conversion

To convert Celsius to Fahrenheit: C × 9/5 + 32. For the reverse: (F - 32) × 5/9. Useful references: body temperature 36.5°C = 97.7°F, boiling point 100°C = 212°F.

Quick Conversion Tips

Save your frequently used conversions with CalKit's unit conversion calculators. Instantly convert length, weight, temperature, area, and more.

Due Date Calculation

The due date is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). According to Naegele's rule, subtract 3 months and add 7 days to the LMP date. However, this is an average estimate, and actual delivery within 2 weeks before or after is considered normal.

Gestational Weeks and Trimesters

• First Trimester (Weeks 1-12): Major organs form during this period, and morning sickness may be severe. Folic acid intake is important.
• Second Trimester (Weeks 13-27): The most stable period. You begin to feel fetal movements, and detailed ultrasound exams are performed.
• Third Trimester (Weeks 28-40): The fetus grows rapidly. Birth preparation and regular checkups are essential.

Weight Management During Pregnancy

Recommended weight gain varies by pre-pregnancy BMI. For normal weight (BMI 18.5-24.9), a gain of 11.5-16 kg is recommended. Excessive weight gain may increase the risk of gestational diabetes or macrosomia.

Using CalKit Pregnancy Calculators

Easily check your due date, current gestational week, recommended weight gain, and fetal growth trends with CalKit's pregnancy calculators.

The Power of Compound Interest

Compound interest earns interest not only on the principal but also on accumulated interest. Einstein reportedly called it the "eighth wonder of the world" due to its powerful effect in long-term investing. At 7% annual compound return, your principal doubles in about 10 years (Rule of 72: 72 ÷ rate = years to double).

ROI (Return on Investment)

ROI = (Net Profit ÷ Investment Cost) × 100%. It is the simplest measure of investment efficiency, but it has limitations as it does not account for the investment time period.

IRR (Internal Rate of Return)

IRR is the discount rate that makes the Net Present Value (NPV) of an investment equal to zero. It is useful for evaluating investments with cash flows over multiple periods. If the IRR exceeds the required rate of return, the investment is considered worthwhile.

NPV (Net Present Value)

NPV is the sum of future cash flows discounted to present value, minus the initial investment. A positive NPV indicates a worthwhile investment. Results vary significantly depending on the chosen discount rate.

Smart Investment Analysis

Do not rely on a single metric to evaluate investments. By analyzing compound interest effects, ROI, IRR, and NPV together, you can make better investment decisions. Try CalKit's investment calculators.