Formula Guides

    How to Calculate

    Step-by-step guides explaining the formulas behind every calculator — with worked examples, variable definitions, common mistakes, and FAQs.

    Math & Science

    5 guides

    How to Calculate Percentage

    How to Use a Scientific Calculator

    How to Solve Algebra Equations

    How to Calculate Mean, Median, Mode & Standard Deviation

    How to Add, Multiply & Find the Determinant of a Matrix

    Finance

    5 guides

    How to Calculate Compound Interest

    How to Calculate a Mortgage Payment

    How to Calculate a Loan Payment (EMI)

    How to Calculate Investment Returns (SIP & Lump Sum)

    How to Calculate Income Tax

    Health & Fitness

    4 guides

    How to Calculate BMI

    How to Calculate Your Daily Calorie Needs (TDEE)

    How to Calculate Body Fat Percentage (Navy Method)

    How to Calculate Your Macros

    Everyday Tools

    4 guides

    How to Calculate a Tip

    How to Calculate Your Exact Age

    How to Convert Units of Measurement

    How to Calculate Days Between Two Dates

    Freelancer & Business

    3 guides

    How to Calculate Your Freelance Hourly Rate

    How to Price a Freelance Project

    How to Calculate Your Break-Even Point

    Real Estate & Rent

    3 guides

    How to Calculate Whether to Rent or Buy a Home

    How to Split Rent Fairly Between Roommates

    How to Calculate Rental Property ROI

    Fitness & Sports

    3 guides

    How to Calculate Your One Rep Max (1RM)

    How to Calculate Running Pace

    How to Calculate Your Daily Water Intake

    Time & Productivity

    3 guides

    How to Convert Between Time Zones

    How to Convert Between Hourly, Monthly & Annual Salary

    How to Calculate the Cost of a Meeting

    Programming & Dev

    4 guides

    How to Convert Between Binary, Decimal, Octal & Hex

    How to Convert HEX, RGB & HSL Colors

    How to Format and Validate JSON

    How to Write and Test Regular Expressions

    Physics & Engineering

    3 guides

    How to Use Ohm's Law — Voltage, Current & Resistance

    How to Calculate Force, Acceleration & Motion (Newton's Laws)

    How to Calculate Series and Parallel Resistance

    Education

    3 guides

    How to Calculate GPA

    How to Calculate Your Current Grade

    How to Count Words and Estimate Reading Time

    Cooking & Kitchen

    3 guides

    How to Scale a Recipe Up or Down

    How to Convert Cooking Measurements

    How to Use Baking Ratios