Calculators
Apps for quickly calculating dates, percentages, tax, and other values.
Elapsed Time Calculator
Calculate elapsed, remaining, and active time from start, end, current time, and breaks, or work out the end time from the active time. Also adds and subtracts durations such as 1:30 or 2h 15m and converts them to decimal hours.
Split Bill Calculator
Work out what each person pays from the total and the head count. Round payments to 10, 100, 500, or 1,000, let some groups pay a larger share or a set amount, and see how much is collected and left over. When several people paid, it also works out who pays whom to settle up.
Sales Tax Calculator
Calculate tax-inclusive and tax-exclusive prices for a given tax rate, with the tax amount rounded down, half up, or up if you choose. For a total with both 10% and 8% items, it works out the tax for each rate from either the sum at each rate or each item's price and quantity.
Age & Date Difference Calculator
Calculate exact age, East Asian age, total days, total weeks, the days until the next birthday, and the Japanese school grade from a start date and a reference date.
Aspect Ratio Calculator
Find the aspect ratio (such as 16:9) from a width and height, and work out the other side when you change the width or height while keeping the same ratio. It also gives the size when a 16:9 image is cropped or padded to another ratio such as 9:16 or 1:1, and how many pixels to cut or add on each side.
Business Day Calculator with Japanese Holidays
Find the date a number of business days after or before a start date, or count the business days between two dates, skipping weekends and Japanese national holidays. List each month's business days with its first, Nth, and last business day. Add New Year closures, extra days off, and your own weekly days off.
Compound Interest and Savings Calculator
Work out what monthly deposits and a starting amount grow to with compound interest, split into contributions and gain, or find the monthly deposit needed to reach a target, with a year-by-year table. You can also see how long a balance lasts when you take out the same amount every month.
Electricity Cost Calculator
Work out the electricity cost of appliances per hour, day, month, and year from their power in watts and how long they run, or from the yearly kWh on a fridge or air conditioner label. Add several appliances to see the total and each one's share, or compare an appliance with its replacement to see the yearly saving and how long it takes to pay back.
Hourly Pay Calculator
Calculate worked hours and a day's pay from an hourly wage, clock-in, clock-out, and breaks, with overtime past 8 hours, late-night work (22:00–05:00), and work on the statutory day off shown separately at premium rates.
Percentage Calculator
Calculate 'B% of A', 'A is what % of B', percent change, a value plus or minus B%, and the whole from a part and its percent. Stacked discounts such as 20% off then another 10% off show the final price and the combined percent. Handy for discounted prices and price increases.
Due Date and Pregnancy Week Calculator (Japan)
Work out the due date, today's week of pregnancy, the Japanese pregnancy month and the trimester from the last period, a known due date, ovulation or an embryo transfer, with cycle length, term dates, Japanese maternity leave dates and the standard schedule of prenatal checkups.
Statistics Calculator (Mean, Median, Standard Deviation)
Paste a list of numbers to get the mean, median, mode, variance, standard deviation, sample variance and quartiles at once, turn a score into a deviation score, and build a frequency table and histogram.
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Tally Counter
A tally counter that runs in your browser. Line up to 20 named counters and set how much each press adds. It shows the total and each share, can undo, counts with the number keys, and can split the counts into time slots such as every 15 minutes, for traffic counts, visitor counts, or tallying votes. Tables copy in a form you can paste into a spreadsheet.
Fuel Cost & Mileage Calculator
Work out the fuel cost and litres of a drive from the distance, the fuel economy in km/L or L/100km, and the price per litre. Switch between one way and a round trip, add tolls and parking, split it with or without the driver, measure mileage by the fill-up method, and read a quick table.
Loan Repayment Calculator
Work out the monthly payment, total repaid and total interest from a loan amount, rate and term, with equal-payment and equal-principal repayment compared side by side, a yearly balance table, and the interest a prepayment saves by shortening the term or lowering the payment.
BMR Calculator
Calculate your basal metabolic rate from sex, age, height, and weight, with the estimated daily energy requirement at low, moderate, and high activity levels and at a target weight. Compare the Japanese DRIs 2025 reference values, the National Institute of Health and Nutrition (Japan) equation, Harris-Benedict, Mifflin-St Jeor, and Katch-McArdle from body fat.
Calculator (Expressions and Functions)
A calculator that takes a whole expression, parentheses included. Handles arithmetic, powers, percentages, square roots, trigonometry, and logarithms, and keeps a history of confirmed calculations. Runs entirely in your browser.
BMI Calculator
Calculate BMI, the corresponding weight category, standard weight, and the normal weight range with the change needed to reach it from height and weight.
Date Calculator: Add or Subtract Days
Find the date and weekday a number of days before or after a start date. Add or subtract years, months, weeks, and days together, count the start date as day 1, and see how many days apart the two dates are.
Prime Factorization, GCD and LCM Calculator
Factor a whole number into primes and see whether it is prime, its divisors, their count and sum, and its simplified square root. With two or more numbers, get the GCD and LCM, the common divisors and the steps of the Euclidean algorithm.
School Entrance and Graduation Year Calculator (Japan)
List the years a person entered and left elementary, junior high, high school and university in Japan from a date of birth, in Western years and Japanese eras, with early-born dates, course length and gap years handled.
Timer and Stopwatch
A countdown timer you set in hours, minutes, and seconds, and a stopwatch that records laps. The timer plays a sound when the time is up and counts the time since. It can be extended a minute at a time while running or after it rings, and shows the time left in the tab title. The stopwatch measures to a hundredth of a second, and the lap list can be copied. Runs entirely in your browser.
Unit Price Comparison Calculator
Work out the price per 100 g, 100 mL, or piece from each item's price and amount, and rank up to 10 items to find the best buy. Handles multipacks, prices before 8% or 10% tax, and percent-off discounts.
