Blog & Guides

Generators How to Generate Random Numbers Online — Complete Guide Learn how random number generators work, how to run fair raffles with no duplicates using Fisher-Yates, and how to generate random numbers in JavaScript, Python, Excel and more. Dev Tools How to Convert Between Timezones — Complete Guide Learn how UTC offsets work, how to handle Daylight Saving Time, schedule international meetings, and convert timezones in JavaScript, Python, Java and more. Dev Tools What is a Unix Timestamp? Complete Guide to Epoch Time Learn what Unix timestamps are, how epoch time works, seconds vs milliseconds, and how to convert timestamps in any programming language. Converters How to Convert Length Units Online Conversion formulas for km to miles, meters to feet, cm to inches and more. Reference tables and instant online converter. Dev Tools How to Generate UUIDs Online Learn what a UUID is, how UUID v4 works, and how to generate unique identifiers for databases, APIs and software projects. Generators How to Generate Secure Passwords Learn what makes a password truly secure and how to create strong, unique credentials for every account. Generators How to Create a QR Code Step-by-step guide to generating custom QR codes for URLs, WiFi networks, plain text and email. Health How to Calculate Your BMI Understand Body Mass Index, how to interpret your result and what the WHO categories mean. Math How to Calculate Percentages Master percentage calculations — increases, decreases, ratios and reverse percentages explained simply. Math How to Calculate Age from Date of Birth Calculate exact age in years, months and days and understand how date arithmetic works. Converters How to Convert Currency Online Convert between world currencies using live exchange rates and understand how currency conversion works. Converters How to Convert Temperature Units Convert between Celsius, Fahrenheit and Kelvin with formulas and instant results explained. Finance How to Calculate Your Mortgage Payment Understand amortization, monthly installments and the true cost of a mortgage loan. Dev Tools How to Format Code Online Format and beautify JSON, HTML, CSS, SQL and more — instantly in your browser. Text Tools How to Count Words and Characters Online Count words, characters, sentences and reading time in any text — useful for writers, SEO and social media. Color How to Convert Color Codes (HEX, RGB, HSL) Convert colors between HEX, RGB and HSL formats and understand when to use each in design. Generators What Is Lorem Ipsum and How to Use It The history of Lorem Ipsum placeholder text and how to generate it for your design projects. Color How to Create a Color Palette Generate harmonious color palettes from any base color using color theory principles. Health How to Calculate Your Running Pace Understand pace, speed and finish time calculations for runners of all levels. Health How to Calculate Heart Rate Zones Find your 5 training zones based on max heart rate and train more effectively. Geo How to Convert GPS Coordinates Convert between decimal degrees, DMS and other GPS coordinate formats with ease. Dev Tools How to Use Regular Expressions (Regex) A practical regex guide with real-world patterns for validation, search and text processing. Converters How to Convert Images Online Convert JPG, PNG, WebP and other formats in your browser — no upload required. Finance How to Calculate Compound Interest Understand how compound interest grows your money and use it to plan your savings. Dev Tools How to Encode and Decode URLs Learn what URL encoding is, when you need it and how to handle special characters in links. Text Tools How to Compare Two Texts Online Find differences between two documents instantly with inline diff highlighting. Math How to Calculate with Fractions Add, subtract, multiply and divide fractions step by step. Covers the LCD method, simplification, mixed numbers and common mistakes to avoid. Math How to Calculate GPA — Complete Guide with Examples Learn exactly how GPA is calculated on the 4.0 scale, what letter grades are worth in grade points, and how to calculate semester and cumulative GPA. Dev camelCase vs snake_case vs kebab-case — Complete Developer Guide When to use each naming convention in JavaScript, Python, CSS, SQL and URLs. Language-by-language cheatsheet with real examples. Finance Salary to Hourly Rate — How to Convert and What to Charge The formula to convert salary to hourly rate, all pay period conversions, and a practical guide for freelancers setting their rates. Health How Sleep Cycles Work — Complete Guide to Better Sleep Learn how 90-minute sleep cycles work, why waking mid-cycle causes grogginess, and how to calculate the best bedtime or wake-up time. Health How Much Water Should You Drink Per Day? Calculate your personal daily water goal by weight, activity and climate. Includes the 35 ml/kg formula, hydration tips and common myths debunked. Health How to Calculate Body Fat Percentage Estimate body fat with the US Navy circumference method or the Deurenberg BMI formula. Understand healthy ranges and measurement tips. Finance How to Calculate Loan Amortization Learn the monthly payment formula, how to read an amortization schedule and the real impact of extra payments on any personal or auto loan. Dev Tools How to Calculate IP Subnets Understand CIDR notation, subnet masks, network and broadcast addresses, usable host ranges and wildcard masks — with worked examples. Productivity How to Build Good Habits That Actually Stick The science of habit formation, why 21 days is a myth, how streaks work, and practical strategies to make habits automatic. Productivity The Pomodoro Technique — A Complete Guide Learn how the Pomodoro Technique works: 25-minute focus sessions, scheduled breaks, and how to adapt the method for different types of work. Date & Time Countdown to Date — How to Count Days Until Any Event Learn how to calculate exactly how many days, hours and minutes remain until any future date. Useful for events, deadlines, holidays and project planning. Date & Time Days Between Dates — Calculate the Difference Between Two Dates Learn how to calculate the exact number of days, weeks and months between any two dates. Understand date arithmetic, leap years and practical use cases. Finance How to Calculate Discounts — Sale Price, Original Price & Percentage Learn how to calculate discount amounts, final sale prices, original prices and discount percentages with simple formulas and worked examples. Health How to Calculate Your TDEE — Total Daily Energy Expenditure Learn how to calculate your TDEE using the Mifflin-St Jeor formula. Understand BMR, activity multipliers and calorie targets for weight loss or gain. Finance How to Calculate a Tip — Guide with Examples Learn how to calculate tips quickly in your head or with a calculator. Includes standard tip percentages, how to split a bill, and worked examples. Converters How to Convert Units — Length, Weight, Speed & More Quick reference tables for length, weight, speed, volume, area and data storage. Common conversions like km to miles, kg to lbs and GB to GiB explained. Dev Tools MD5 vs SHA-256: When to Use Each Hash Algorithm Learn the difference between MD5, SHA-1, SHA-256 and SHA-512. When each is safe to use, how to verify file checksums, and why MD5 is not safe for passwords.