Calculator tools
Run common calculations such as percentages and BMI instantly, with formulas, examples and reference tables on the same page.
Featured calculators
BMI Calculator — Body Mass Index
Calculate BMI from height and weight and see the category: underweight, normal, overweight, obese.
Percentage Calculator — X is what % of Y
Instantly calculate ratios (X is what % of Y), part values, discounts and percent change with this percentage calculator.
Discount Calculator — Sale Price from Original Price
Enter an original price and discount rate to calculate the discount amount and final sale price.
VAT Calculator — 10% Tax from Net Amount
Calculate 10% VAT and gross amount from a net amount.
Average Calculator — Mean from Sum and Count
Calculate the arithmetic mean from a sum and item count.
Weighted Average Calculator
Calculate weighted average from the sum of value×weight and the sum of weights.
Ratio Calculator — Simplify A:B
Enter two numbers and reduce them to the simplest A:B ratio.
Rule of Three Calculator — Find X from Three Values
Calculate X in the proportion A:B = C:X from three known values.
Exponent Calculator — Base and Power
Enter a base and exponent to calculate a power value aⁿ.
Square Root Calculator
Enter a number to calculate its real square root.
Factorial Calculator — Calculate n!
Calculate n! for integers from 0 to 170.
Permutation and Combination Calculator — nPr nCr
Calculate permutations (nPr) and combinations (nCr) for choosing r items from n.
GCD and LCM Calculator
Calculate the greatest common divisor and least common multiple of two integers.
Tip Calculator — Split Tip and Total
Calculate tip, total, and per-person amount from bill, tip rate, and people.
Compound Interest Calculator
Calculate future value and interest from principal, annual rate, and years.
Loan Payment Calculator — Monthly Payment
Estimate equal monthly loan payment from loan amount, annual rate, and months.
Break-even Calculator — BEP Units
Calculate break-even units from fixed cost, unit price, and variable cost.
GPA Converter — Korea Life Calculator
converts a 100-point score to a 4.5-scale GPA.
Grade Point Calculator — Korea Life Calculator
calculates average grade points from total quality points and credits.
Shoe Size Converter — Korea Life Calculator
converts Korean millimeter shoe size to reference US and EU sizes.
Clothing Size Converter — Korea Life Calculator
estimates Korean clothing size from chest circumference in centimeters.
Korean Ring Size Converter — Korea Life Calculator
estimates Korean ring size from inner diameter in millimeters.
Weekly Holiday Pay Calculator — Korea Life Calculator
calculates weekly holiday pay from hourly wage and weekly scheduled hours.
Hourly Wage Calculator — Korea Life Calculator
calculates hourly wage from monthly pay and monthly work hours.
Severance Pay Calculator — Korea Life Calculator
estimates severance pay from average daily wage and service days.
Savings Interest Calculator — Korea Life Calculator
estimates savings maturity amount from monthly deposit, term, and annual rate.
Jeonse to Monthly Rent Converter — Korea Life Calculator
converts a jeonse deposit gap to monthly rent using an annual conversion rate.
Korean Housing Area Calculator — Korea Life Calculator
estimates supply area from exclusive area and exclusive ratio.
Korean Four Insurance Calculator — Korea Life Calculator
estimates employee-side Korean pension, health, long-term care, and employment insurance from monthly pay.
Korean Net Salary Calculator — 2026 Take-Home Pay
Estimate monthly take-home pay in Korea: annual salary minus 2026 employee-side social insurance, plus your withholding tax from the NTS simplified tax table.
Korean Car Tax Calculator — Korea Life Calculator
estimates annual Korean passenger car ownership tax and local education tax from engine size and vehicle age.
Korean Acquisition Tax Calculator — Korea Life Calculator
estimates basic Korean residential acquisition tax and local education tax from purchase price.
Korean Property Tax Calculator — Korea Life Calculator
estimates Korean residential property tax and local education tax from standard value and fair market value ratio.
Unemployment Benefit Calculator — Korea HR and Payroll Calculator
estimates daily and total job-seeking benefits from average daily wage, age, and insured period. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Annual Leave Calculator — Korea HR and Payroll Calculator
estimates earned and remaining annual leave from service months, attendance rate, and used leave. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Minimum Wage Calculator — Korea HR and Payroll Calculator
checks whether hourly or monthly pay meets the 2026 Korean minimum wage. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Daily Worker Tax Calculator — Korea HR and Payroll Calculator
estimates daily worker earned-income withholding from daily pay and work days. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Freelancer 3.3% Tax Calculator — Korea HR and Payroll Calculator
calculates 3.3% business-income withholding and net pay. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Parental Leave Pay Calculator — Korea HR and Payroll Calculator
estimates monthly parental leave benefits from ordinary monthly wage and leave months. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Maternity Leave Pay Calculator — Korea HR and Payroll Calculator
estimates maternity leave pay split by employment insurance and employer gap. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Inclusive Wage Calculator — Korea HR and Payroll Calculator
checks minimum wage and fixed overtime basics from base pay and inclusive overtime pay. It uses official Korean references checked on 2026-06-26 and calculates in your browser.
Gift Tax Calculator — Korea Real Estate and Tax Calculator
estimates gift tax from gift amount, relationship, deductions, and generation-skip status. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Inheritance Tax Calculator — Korea Real Estate and Tax Calculator
estimates inheritance tax from estate value, deductions, and number of heirs. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Comprehensive Real Estate Tax Calculator — Korea Real Estate and Tax Calculator
estimates comprehensive real estate tax from public price, house count, deduction, and fair-market ratio. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Brokerage Fee Calculator — Korea Real Estate and Tax Calculator
calculates maximum housing brokerage fee and VAT from transaction type and amount. It uses official Korean references checked on 2026-06-26 for general-case estimates.
National Housing Bond Calculator — Korea Real Estate and Tax Calculator
calculates bond purchase and immediate-sale cost from basis amount, purchase rate, and discount rate. It uses official Korean references checked on 2026-06-26 for general-case estimates.
DSR/DTI/LTV Calculator — Korea Real Estate and Tax Calculator
calculates loan ratios and reference limits from income, debt payments, collateral, and loan amount. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Rental Yield Calculator — Korea Real Estate and Tax Calculator
calculates gross and net rental yield from purchase price, deposit, rent, and costs. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Deemed Rent Calculator — Korea Real Estate and Tax Calculator
estimates deemed rental income from deposits, deduction, and deposit interest rate. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Year-End Tax Refund Calculator — Korea Real Estate and Tax Calculator
estimates determined tax and refund from gross salary, withholding, deductions, and credits. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Comprehensive Income Tax Calculator — Korea Real Estate and Tax Calculator
estimates comprehensive income tax from income, expenses, deductions, and tax credits. It uses official Korean references checked on 2026-06-26 for general-case estimates.
Fraction Calculator — Operations and Simplification
Calculate addition, subtraction, multiplication, and division for two fractions and simplify the result.
Prime Checker — Test Whether an Integer Is Prime
Enter an integer and check whether it is divisible only by 1 and itself.
Prime Factorization Calculator
Enter an integer and decompose it into a product of prime factors.
Quadratic Equation Calculator — Quadratic Formula
Calculate the discriminant and roots for ax²+bx+c=0.
Standard Deviation Calculator — Population Standard Deviation
Enter a list of numbers to calculate mean, variance, and population standard deviation.
Median Calculator — Middle Value of a Number List
Sort a list of numbers and calculate the middle value.
Percentile Calculator — pth Percentile Value
Enter numbers and percentile p to calculate the corresponding percentile value.
Circle Area Calculator — Area from Radius
Enter radius to calculate the area of a circle.
Triangle Area Calculator — Base and Height
Enter base and height to calculate triangle area.
Rectangle Area Calculator — Width and Height
Enter width and height to calculate rectangle area.
Sphere Volume Calculator — Volume from Radius
Enter radius to calculate sphere volume.
Cylinder Volume Calculator — Radius and Height
Enter radius and height to calculate cylinder volume.
Pythagorean Calculator — Right Triangle Hypotenuse
Enter two right-triangle sides a and b to calculate hypotenuse c.
Tally Counter — Click Counter
Manually count quantities with increment, decrement, and reset buttons.
Sales Tax Calculator — Global SEO Calculator
calculates tax amount and total from a price and manually entered tax rate.
Scientific Notation Converter — Global SEO Calculator
converts a number into coefficient and power-of-ten notation.
Significant Figures Calculator — Global SEO Calculator
rounds a number to a requested count of significant figures.
Square Footage Calculator — Global SEO Calculator
calculates square footage and optional cost from room dimensions.
Amortization Schedule Calculator — Global SEO Calculator
calculates monthly payment and amortization breakdown from principal, APR, and term.
Macro Calculator — Global SEO Calculator
estimates target calories and macros with the Mifflin-St Jeor equation.
Protein Calculator — Global SEO Calculator
calculates daily protein range from body weight and g/kg target.
Sleep Cycle Calculator — Global SEO Calculator
suggests bedtimes or wake times using 90-minute sleep cycles.
Percent Error Calculator — Global SEO Calculator
calculates absolute error and percent error from observed and true values.
Slope Calculator — Global SEO Calculator
calculates line slope and y-intercept from two points.
Kimchi Ingredient Calculator — Browser Everyday Tool
estimates kimchi seasoning ingredients from napa cabbage weight. Input is processed only in your browser.
Ohm's Law Calculator — Voltage, Current, Resistance, Power
Enter any two of voltage (V), current (I), resistance (R), or power (P) to calculate the other two.
Watts to Amps Calculator — DC, AC Single-Phase, Three-Phase
Convert power in watts to current in amps for DC, AC single-phase, and AC three-phase circuits with power factor.
Amps to Watts Calculator — DC, AC Single-Phase, Three-Phase
Convert current in amps to power in watts for DC, AC single-phase, and AC three-phase circuits with power factor.
Watts to kWh Calculator — Energy from Power and Hours
Enter appliance power in watts, daily hours, and days to calculate energy in kilowatt-hours.
Korean Electricity Bill Calculator — Residential Progressive Rates
Estimate a Korean residential electricity bill from monthly kWh usage, including base charge, progressive energy charges, VAT, and the power fund.
kVA to Amps Calculator — Single-Phase and Three-Phase
Convert apparent power in kVA to current in amps for single-phase and three-phase circuits.
Amps to kVA Calculator — Single-Phase and Three-Phase
Convert current in amps to apparent power in kVA for single-phase and three-phase circuits.
Power Factor Calculator — PF and Reactive Power from kW and kVA
Calculate power factor (PF) and reactive power (kvar) from real power (kW) and apparent power (kVA).
Voltage Divider Calculator — Vout from R1 and R2
Calculate the output voltage of a two-resistor voltage divider from input voltage, R1, and R2.
Resistor Color Code Calculator — 4-Band and 5-Band Values
Pick resistor band colors to decode 4-band and 5-band resistance values with tolerance.
mAh to Wh Converter — Battery Capacity to Watt-Hours
Convert battery capacity in mAh and voltage to energy in Wh, useful for airline power bank limits.
Wh to mAh Converter — Watt-Hours to Battery Capacity
Convert energy in Wh and voltage to battery capacity in mAh.
Calorie Calculator — Daily Needs & TDEE
Calculate BMR and daily maintenance calories (TDEE) from sex, age, height, weight, and activity level, with cut and bulk targets.
BMR Calculator — Mifflin-St Jeor vs Harris-Benedict
Calculate basal metabolic rate (BMR) from sex, age, height, and weight with both the Mifflin-St Jeor and revised Harris-Benedict equations.
Body Fat Calculator — US Navy Method
Estimate body fat percentage from neck, waist (and hip) circumferences and height using the US Navy method, compared with the BMI method.
Ideal Weight Calculator — Devine, Robinson, Miller, BMI 22
Calculate ideal body weight from height and sex with the Devine, Robinson, and Miller formulas plus the BMI 22 method, shown as a range.
Running Pace Calculator — Distance, Time, Pace
Enter any two of distance, time, and pace to get the third, with projected finish times for 5K, 10K, half, and full marathon.
Calories Burned Calculator — MET Based
Calculate calories burned for walking, running, cycling, swimming, and more from the activity MET value, body weight, and duration.
BAC Calculator — Widmark Formula
Estimate blood alcohol concentration with the Widmark formula from drink volume, ABV, body weight, and elapsed time, with Korean DUI thresholds (0.03%/0.08%).
Water Intake Calculator — By Weight & Activity
Calculate a recommended daily water intake range from body weight and exercise time, compared with EFSA and U.S. National Academies references.
Simple Interest Calculator — Interest from Principal, Rate, Time
Enter principal, annual rate, and years to calculate simple interest and the maturity amount, with a compound comparison.
Auto Loan Calculator — Monthly Payment and Total Interest
Calculate the amortized monthly payment and total interest from vehicle price, down payment, rate, and term.
Loan Prepayment Fee Calculator — Early Repayment Penalty
Estimate a loan prepayment fee from the repaid amount, fee rate, remaining days, and total loan period.
Savings Goal Calculator — Monthly Saving for a Target Amount
Enter a target amount, months, and annual return to find how much to save every month.
Unit Price Calculator — Compare Price per 100g/100ml
Enter the price and size of two products to compare unit prices and find which one is cheaper.
Fuel Cost Calculator — Trip Cost from Distance and Fuel Economy
Enter trip distance, fuel economy (km/L), and fuel price per liter to calculate fuel needed and trip cost.
Speed Distance Time Calculator — Solve for the Missing Value
Enter any two of speed, distance, and time to calculate the third using v = d ÷ t.
Final Grade Calculator — Score Needed on the Final Exam
Calculate the minimum final exam score you need from your current grade, target grade, and final weight.
Test Grade Calculator — Score and Letter Grade from Wrong Answers
Enter the number of questions and wrong answers to get the score percentage and letter grade.
Molar Mass Calculator — g/mol from a Chemical Formula
Type a chemical formula like H2O or CaCO3 to calculate its molar mass using IUPAC standard atomic weights.
Dog Age Calculator — Dog Years to Human Years by Size
Convert your dog’s age to human years by breed size, with the newer DNA-based logarithmic formula shown alongside.
Cat Age Calculator — Cat Years to Human Years
Enter your cat’s age to convert it to human years using the 15 + 9 + 4-per-year veterinary rule.
Korea Capital Gains Tax Calculator — Property Sale Tax with 2026 Rates
Estimates Korean real estate capital gains tax and local income tax from sale price, acquisition cost, expenses, and holding and residence years, using 2026 rates checked on 2026-07-06. Simulation only; multi-home surcharges are excluded.
Building Coverage Ratio and FAR Calculator — Korean Zoning Limits
Calculates building coverage ratio and floor area ratio from land, building, and total floor area, and compares them with Korean zoning caps under the National Land Planning Act. Actual limits are set by local ordinances.
Korea Real Estate Registration Cost Calculator — Taxes, Bond, and Fees
Estimates the total cost of a Korean home ownership-transfer registration: acquisition tax, local education tax, rural special tax, national housing bond immediate-sale cost, and judicial scrivener fee. Simulation based on references checked on 2026-07-06.
English Test Score Converter — TOEIC, TOEFL iBT, IELTS, OPIc
Converts TOEIC, TOEFL iBT, and IELTS scores into equivalent bands based on official comparison studies, with OPIc and TOEIC Speaking reference levels used in Korean hiring. Reference only; no official cross-test formula exists.
Dutch Pay Calculator — Split Bills with Partial Participants
Enter payer, amount, and participants per item to calculate each person’s share and a minimal settlement table in your browser.
Drinking Settlement Calculator — Time-Weighted Bill Split
Split a night-out bill by attendance hours and paid amount, then generate a transfer table.
Stock Average Price Calculator — Average Down After Buying More
Calculate the new average cost, total investment, and break-even price after an additional stock purchase.
Coffee Brew Ratio Calculator — Coffee to Water
Calculate water amount and total brew input from coffee grams and a brew ratio in your browser.
Alcohol Dilution Calculator — Water for Target ABV
Calculate water to add and final volume from current volume, current ABV, and target ABV.
Baggage Weight Distribution Calculator — Bag Limit Check
Calculate even weight per bag and over/under allowance from total weight, bag count, and per-bag limit.
Loan Refinance Break-Even Calculator — Months to Recover Cost
Estimate monthly interest savings and break-even months from balance, old rate, new rate, and switching costs.
Recipe Scaler — Browser Calculator
scales ingredient quantities from original servings to target servings. Input is calculated only in your browser.
Pet Food Amount Calculator — Browser Calculator
estimates daily pet food amount from weight, activity factor, and food calories. Input is calculated only in your browser.
FIRE Calculator — Browser Calculator
estimates time to financial independence from expenses, portfolio, savings, and returns. Input is calculated only in your browser.
Savings Ladder Simulator — Browser Calculator
estimates maturity flow for a monthly savings ladder. Input is calculated only in your browser.
Running Race Predictor — Browser Calculator
predicts race time for another distance from a recent race result. Input is calculated only in your browser.
Heart Rate Zone Calculator — Browser Calculator
calculates Karvonen training zones from maximum and resting heart rate. Input is calculated only in your browser.
Paint Wallpaper Tile Calculator — Browser Calculator
calculates cans, rolls, or boxes needed from area and product coverage. Input is calculated only in your browser.
Curtain and Blind Size Calculator — Browser Calculator
calculates order dimensions from measured window size and fullness factor. Input is calculated only in your browser.
Even Pace Training Table — Browser Time Planning Tool
calculates even pace and cumulative split times from target distance and time. Input is processed only in your browser.
FAQ
Can I see the formula behind each calculator?
Yes. Calculator pages include the interactive result, formula, example table and FAQ.
Are health calculator results medical advice?
No. Tools such as BMI are informational and do not replace professional medical guidance.
Are Korea-specific calculators covered?
Yes. Korean payroll, insurance and tax calculators state their basis date and official sources alongside the result.
Is my input sent to a server?
No. Calculations run in the browser and input is not sent to a server.