Calc Tani - Online Calculator Collection

16 free online calculators for exchange rates, salary, BMI, severance pay, interest, and more. Use instantly without installation.

Scientific CalculatorTrigonometry, logarithms, and engineering calculations Exchange Rate CalculatorCurrency conversion with real-time exchange rates Severance Pay CalculatorAuto-calculate severance pay by tenure Interest CalculatorQuick simple and compound interest calculation Salary CalculatorCheck gross/net salary and take-home pay Korean Age CalculatorCalculate exact age from date of birth Ovulation CalculatorPredict ovulation and fertile window by cycle Bill SplitterSplit group expenses fairly per person BMI CalculatorMeasure BMI from height and weight VAT CalculatorAuto-calculate supply price and VAT Loan CalculatorSimulate equal principal and installment repayments Rent Conversion CalculatorConvert between deposit and monthly rent Discount CalculatorSee discount rate and final price at a glance Social Insurance CalculatorCalculate 4 major social insurance premiums Freelancer 3.3% Tax CalculatorCalculate freelancer 3.3% withholding tax Stock Return CalculatorAnalyze stock returns from buy/sell prices

Key Features

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Offline Support

Install as PWA for offline use

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Dark Mode

Dark theme to reduce eye strain

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Responsive Design

Optimized for mobile, tablet, and desktop

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Multi-language

Korean and English interface

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Completely Free

All features free without sign-up

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Fast Loading

Optimized performance for quick start

What is Calc-Tani?

Calc-Tani is a free online calculator platform that provides all the calculators you need for daily life and work in one website. From exchange rate calculators to salary, loan, and BMI calculators — all 16 tools are available instantly in your browser without any installation.

Built for office workers, freelancers, students, and business owners — anyone who needs accurate calculations. Each tool offers an intuitive UI and precise results designed for real-world use.

All features are completely free without registration or app installation. Your personal data is stored only in your browser to protect your privacy.

Which Calculator Should You Choose?

Find the best calculator for your situation.

Scientific CalculatorScience & Engineering

Perform trigonometry, logarithms, square roots, and other engineering calculations conveniently on the web.

Exchange Rate CalculatorRemittance & Travel

Quickly convert between currencies using real-time exchange rates.

Severance Pay CalculatorRetirement Planning

Automatically calculate statutory severance pay based on tenure and average wages.

Interest CalculatorSavings & Investment

Calculate deposit interest and final amount using simple or compound interest methods.

Salary CalculatorPaycheck Check

Check your take-home pay after deducting social insurance and income tax from gross salary.

Korean Age CalculatorAge Check

Enter your date of birth to calculate international age, Korean age, and year-based age.

Loan CalculatorLoan Planning

Compare monthly payments across different repayment methods: equal installment, equal principal, and bullet repayment.

Social Insurance CalculatorEmployers & Employees

Calculate individual contributions for national pension, health insurance, employment insurance, and industrial accident insurance.

Stock Return CalculatorStock Investment

Analyze actual returns and profit/loss reflecting buy/sell prices and commission fees.

In-Depth Guides

Beyond the numbers — why each formula works, explained with worked 2026 examples.

GUIDE · 7 MIN

Gross vs. Net Salary in Korea: Why the Gap? (2026 Guide)

A full breakdown of why your Korean contract salary differs from take-home pay — national insurance, income tax, and non-taxable allowances explained with 2026 rates.

GUIDE · 8 MIN

Korean Severance Pay 2026: Calculation and Retirement Tax Explained

How severance is calculated from average wages, 2026 retirement income tax deductions, and IRP rollover tax benefits — with worked examples.

GUIDE · 6 MIN

When Does Refinancing a Loan Pay Off? A Break-Even Framework

A break-even formula for loan refinancing that factors in prepayment penalties and rate reduction, illustrated with three real-world scenarios.

GUIDE · 5 MIN

5 Reasons BMI Alone Misleads — and What to Measure Alongside

Why BMI misclassifies muscular, elderly, or abdominally obese individuals — and which complementary metrics to use.

View all guides →

Frequently Asked Questions

Is Calc-Tani free?

Yes, all features are completely free. No registration is required.

Can I use it on mobile?

Yes, the responsive design provides an optimized experience on mobile, tablet, and desktop. You can also install it as a PWA to use it like an app.

Is my data safe?

All calculations are processed in your browser. Your input data is never sent to any server, and no personal information is collected.

Are the calculation results accurate?

Each calculator is implemented based on relevant regulations and formulas. However, actual taxes and insurance premiums may vary depending on individual circumstances, so please use the results as a reference.

Which browsers are supported?

Works on all modern browsers including Chrome, Safari, Firefox, and Edge. We recommend using the latest version for the best experience.

How can I suggest features or report bugs?

Please send an email to admin@teck-tani.com and we'll review your feedback.