Guides & explainers

Knowledge base

Short articles that go deeper on the ideas behind the calculators. Always free to read in your browser.

• What is EMI?Learn what EMI is, how the amortization formula works, and how to calculate your monthly loan payment. Includes examples for mortgages and personal loans.
• What is Base64 Encoding?A clear explanation of Base64 encoding — what it is, why it exists, and how to encode and decode text or binary data using it.
• How to Convert UnitsA practical guide to converting between metric and imperial units. Includes the most common conversions and the formulas behind them.
• What Is a Percentage?Learn what percentages are, how to calculate them, and where they appear in everyday life — from discounts and interest rates to test scores and statistics.
• What Is a UUID?Understand UUIDs — universally unique identifiers. Learn the difference between UUID v4 and v7, how they are generated, and when to use them in software development.
• What Is JSON?Learn what JSON (JavaScript Object Notation) is, how to read and write it, common syntax errors, and best practices for using JSON in APIs and configuration files.
• How to Use Base64 EncodingUnderstand Base64 encoding — what it is, how it works, when to use it, and common pitfalls. Includes examples for encoding images, JSON payloads, and credentials.
• How to Calculate a Loan EMILearn how to calculate Equated Monthly Installments (EMI) for a loan. Understand the EMI formula, how interest rate and tenure affect payments, and tips to reduce total interest paid.
• What Is BMI?Learn what Body Mass Index (BMI) is, how it is calculated, what BMI ranges mean for health, and when BMI may not be the best measure to use.
• What Is BMR (Basal Metabolic Rate)?Understand Basal Metabolic Rate (BMR), how it is calculated with Mifflin-St Jeor and Harris-Benedict equations, and how to use it to manage your weight.
• How to Count Calories for Weight Loss or GainA practical guide to counting calories — calculating your TDEE, setting a calorie target, tracking macros, and avoiding common mistakes that stall progress.
• What Is a JWT (JSON Web Token)?Learn what JSON Web Tokens are, how they are structured, how signature verification works, and best practices for using JWTs securely in web applications.
• What Is Regex? A Beginner's Guide to Regular ExpressionsLearn what regular expressions (regex) are, how to read and write common patterns, and how to use regex for searching, validation, and text transformation.
• What Is a QR Code and How Does It Work?Learn what QR codes are, how they encode data, what the different parts of a QR code do, and how to generate and scan them for URLs, contacts, and payments.
• How to Calculate Mortgage PaymentsLearn how monthly mortgage payments are calculated, what factors affect your repayment, the difference between fixed and variable rates, and how to reduce total interest paid.
• What Is Compound Interest and How Does It Work?Understand compound interest, how it differs from simple interest, how compounding frequency affects growth, and how to use the compound interest formula to grow savings.
• How to Calculate GST and VATLearn how to calculate GST (Goods and Services Tax) and VAT (Value Added Tax), add tax to a price, extract tax from a gross amount, and understand tax-inclusive vs exclusive pricing.
• How to Convert Temperature UnitsLearn the formulas to convert between Celsius, Fahrenheit, and Kelvin temperature scales, with worked examples and a quick-reference conversion table for common values.
• What Is Markdown? A Plain-Text Formatting GuideLearn what Markdown is, how its basic syntax works for headings, lists, links, and code, and where Markdown is used — from GitHub READMEs to documentation and blogs.
• How to Calculate a Tip and Split a BillLearn how to calculate a tip, choose an appropriate tip percentage, split a restaurant bill evenly or by individual items, and handle the maths when people order different amounts.
• What Is Cron? A Guide to Cron Expressions and SchedulingLearn what cron is, how cron expressions work, how to read and write schedule patterns with the five-field syntax, and common cron examples for everyday scheduling tasks.
• How to Calculate Age from a Date of BirthLearn how to accurately calculate age in years, months, and days from a date of birth, how leap years affect the calculation, and common pitfalls in age arithmetic.
• What Is Lorem Ipsum? The History of Placeholder TextLearn what Lorem Ipsum placeholder text is, where it comes from, why designers use it, and when to use real content instead of dummy text in your projects.
• What Is Binary? Number Systems ExplainedLearn how binary, octal, and hexadecimal number systems work, how to convert between them and decimal, and why computers use binary internally for all data.
• How to Calculate Your Retirement Savings GoalLearn how to estimate the savings needed for retirement using the 4% rule, how to factor in inflation, Social Security or pension income, and how to close a savings gap.
• How to Set and Reach a Savings GoalLearn how to calculate how long it will take to reach a savings target, how much to save each month, and strategies to accelerate progress toward any financial goal.
• What Is CSS Box Shadow? A Complete GuideLearn how the CSS box-shadow property works, what each parameter controls, how to layer multiple shadows, and how to create common shadow effects for cards and buttons.
• How to Calculate Fuel Cost for a TripLearn how to calculate fuel cost for any journey using consumption rate and fuel price, compare petrol vs diesel vs EV costs, and estimate annual vehicle running costs.
• Sleep Cycles Explained: How to Wake Up Feeling RestedLearn how sleep cycles and REM sleep work, why waking between cycles leaves you feeling refreshed, how long each cycle lasts, and how to calculate the best bedtime or wake time.
• How to Track Work Hours and Calculate PayLearn how to track work hours accurately, calculate regular and overtime pay, convert between hourly and annual salary, and comply with working time rules.
• What Is a CSS Gradient? Linear, Radial, and Conic GradientsLearn how CSS gradients work, the syntax for linear, radial, and conic gradients, how to add colour stops, angles, and transparency, and when to use each gradient type.
• How to Generate and Manage Secure PasswordsLearn what makes a password strong, how password generators create random passwords, and how to manage dozens of strong passwords without memorising them all.
• What Is URL Encoding and When Do You Need It?Learn what URL encoding (percent-encoding) is, which characters must be encoded in URLs, the difference between encodeURI and encodeURIComponent, and how to decode URLs.
• What Is Colour Theory? HEX, RGB, and HSL ExplainedLearn the fundamentals of digital colour theory, how HEX, RGB, and HSL colour models work, how to convert between them, and how to build accessible colour palettes.
• How to Calculate the Difference Between Two DatesLearn how to calculate the exact number of days, weeks, months, and years between two dates, handle leap years correctly, and work with time zones in date arithmetic.