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Utility Tools
Everyday utilities - QR code generation, discount calculation, unit conversion, notepad and more. Handy for shopping, work and daily life.
About this category
The utility tools help with everyday tasks: QR code generation, discount calculation, unit conversion, a browser notepad and more. From shopping math to work documents and daily notes, just open your browser and go.
QR Code Generator
Generate QR codes from URLs or text for free. Customize colors and sizes.
Text Converter
Convert case (lowercase, uppercase, title case) and clean up text: remove blank lines, trim spaces, and count characters, lines and UTF-8 bytes.
Color Converter
Convert between HEX, RGB and HSL. Pick colors directly with the color picker.
Date Calculator
Calculate the difference between two dates in days. Add or subtract days from any date.
Discount Calculator
Calculate final price and savings for one or two percentage discounts. Stack 30% off with 10% off to see the true 37% effective discount.
Tax Calculator
Calculate tax-included and tax-excluded prices with automatic tax amounts. Supports 10%, 8% and custom rates.
Unit Converter
Convert length, weight and temperature instantly. Meters, inches, kilograms, pounds and more.
Browser Notepad
A free notepad that runs entirely in your browser. Your notes are saved automatically on your device and restored next time.
Age Calculator
Calculate your exact age from your birth date, including days until your next birthday.
Kanji Number Converter
Convert between Arabic numerals and Kanji numerals (一, 十, 百, 千, 万).
Timer & Stopwatch
Countdown timer and stopwatch right in your browser. Great for cooking, studying, workouts and timing.
Calculator
A free calculator that runs in your browser. Four basic operations, percentage, sign toggle and full keyboard support.
Percentage Calculator
Three modes for instant percentage math: X% of a total, X as a % of Y, and increase or decrease by X%.
BMI Calculator
Calculate your BMI from height and weight, with the Japanese classification and healthy weight range.
Random Number Generator
Generate random numbers in any range. Duplicate control and sorting included - ideal for draws and raffles.
Full-width / Half-width Converter
Convert between full-width and half-width characters. Handles letters, digits, symbols, spaces, and katakana with voiced marks.
Roman Numeral Converter
Convert between Arabic numerals and Roman numerals (I, V, X and more). Supports 1-3999 and tolerates non-standard forms like clock-face IIII.
Timezone Converter & World Clock
Compare current dates and times in Tokyo, New York, London and other cities, with each time difference measured from Tokyo.
Split Bill Calculator
Split a bill evenly from the total and number of people. Choose how to round the remainder - up, down, nearest, or the organizer pays the difference.
Calorie & BMR Calculator
Estimate adult resting energy expenditure (REE) and daily expenditure using an activity factor. Explore the formula and assumptions; this is not a diet prescription.
Area & Volume Calculator
Calculate the area of 2D shapes (square, rectangle, triangle, circle) and the volume of 3D shapes (cube, cylinder, sphere). Any unit, with liter conversion.
Data Size Converter
Convert between bit, byte, KB, MB, GB, TB and PB. Switch between binary (1024) and decimal (1000) conventions to answer "how many MB in 1GB?" accurately.
Rokuyo Calendar & Lunar Date
Pick a date to instantly see its Rokuyo (Taian, Butsumetsu...), lunar date, Chinese zodiac and solar terms. Handy for choosing wedding, moving or opening dates.
Color Palette Generator
Generate complementary, analogous, triadic and monochrome palettes. View HEX, RGB and HSL values and copy HEX codes for your designs.
Time Duration Calculator
Find the duration between two times, or add and subtract hours and minutes. Times past midnight are handled automatically - great for work estimates.
Contrast Checker
Calculate the contrast ratio between text and background colors and check WCAG conformance (AA, AAA) instantly — for readable, accessible color combinations.
Statistics Calculator
Paste numbers to get count, sum, mean, median, min, max and standard deviation at once. Handles newline, comma and space separators.
Fraction Calculator
Add, subtract, multiply and divide fractions with exact results. See the reduced answer plus mixed-number and decimal forms, with the working shown.
Prime Factorization
Factor an integer at least 2 with up to 15 digits. Check product and exponent forms, positive divisor count and primality. Press Factorize or Enter to run.
Data Size & Transfer Time Calculator
Compute the data size of images, audio and video, and the time needed to transfer data — with both 1024-based and 1000-based unit conversions and the working shown. Useful for IT classwork and exam practice.
Related articles
GuideBMI Calculation Guide: Formula, Japanese vs CDC Categories & Reference Weight Table
Calculate Adult BMI (weight in kg / height in m²) with a 170 cm, 65 kg worked example. Compare Japan's 6-tier JASSO classification with WHO/CDC boundaries, check the 150–185 cm BMI-22 reference table, and review age-specific target BMI ranges.
GuideBMR & TDEE Calorie Calculation Guide: Mifflin–St Jeor Formula, Activity Multipliers & Age Table
Calculate resting energy expenditure (BMR/REE) and total daily energy expenditure (TDEE) with the Mifflin–St Jeor equation. Includes a 30-year-old, 175 cm, 70 kg worked example, 5 activity factors, age/sex reference tables, and why fixed calorie deficits have limits.
GuideRokuyo Explained: Japanese Lucky & Unlucky Days (Taian, Butsumetsu, Tomobiki) & Lunar Formula
Complete guide to Japan's six Rokuyo calendar labels (Sensho, Tomobiki, Senbu, Butsumetsu, Taian, Shakko). Learn their meanings, time-of-day rules, wedding and funeral customs, the (Lunar Month + Day) mod 6 formula, and 2026–2027 worked examples.
FAQ
Do I need to register?
No. All tools are free and require no registration.
Where is my input stored?
Processing happens in your browser. Features that save data (like the notepad) store it only in your device's local storage.