How to Calculate Percentage
Learn the essential percentage formulas and choose the right method for any percentage question.
Read guidePercentage Formula Explained
Understand the percentage formula, its variables and the most common ways to rearrange it.
Read guideHow to Calculate Percentage Change
Calculate increases and decreases from an original value and understand the result correctly.
Read guideHow Discount Calculations Work
Turn a discount rate into money saved and the final price using two clear steps.
Read guideHow to Calculate Percentage Increase
Learn the percentage increase formula with step-by-step examples. Calculate growth, raises and price increases.
Read guideHow to Calculate Percentage Decrease
Learn the percentage decrease formula with examples. Calculate price drops, reductions and losses.
Read guidePercentage Change vs Percentage Difference
Understand when to use percentage change and when to use percentage difference. They are not the same.
Read guideMarkup vs Margin: What's the Difference?
Learn the critical difference between markup and profit margin. Both use cost and price but answer different questions.
Read guideHow to Calculate Tax on a Price
Learn how to add tax to a price and how to find the pre-tax price from a total. Step-by-step examples.
Read guideHow to Calculate a Tip and Split the Bill
Learn how to calculate tips, split bills and figure out how much each person pays. Quick formulas for dining out.
Read guideHow to Convert Fractions, Decimals and Percentages
Master conversions between fractions, decimals and percentages. Complete guide with all formulas and examples.
Read guideHow to Calculate Age — Complete Guide
Learn how age is calculated from a birth date, including years, months, days, leap years and common edge cases.
Read guideHow Age Is Calculated — Behind the Algorithm
Understand the calendar math behind age calculation: subtracting dates, handling leap years and counting total days.
Read guideHow Many Days Have I Lived?
Learn how to count every day you have been alive, why the number surprises most people and how to find milestone days.
Read guideLeap Year Birthday — How Age Is Calculated for Feb 29
How age works when you were born on February 29. Learn the legal and mathematical conventions for leap day birthdays.
Read guide