A good place to start
Everyday calculations
Reverse percentages: find the original price before a discount
Work backward from a sale price or an increased amount, with checks for stacked discounts and a 100% reduction.
Read the guidePercentEase Guides & explainers
Open calculator Make the numbers make sense.
Guides, tutorials, and tips on using percentages in everyday life — from shopping discounts and tipping to finance, statistics, and math fundamentals.
Everyday calculations
How to Calculate Tips Using Percentages
Choose the bill amount B, your own tip rate r and a whole number of people n.
Percentage Calculator for Shopping: How to Calculate Discounts
For original price P and discount d, savings are P × d / 100 and the final price is P minus those savings.
Everyday Percentage Tips and Tricks
Practical percentage shortcuts for shopping discounts, tipping, budgeting, cooking adjustments, and more real-world scenarios.
Business arithmetic
Margin vs markup: why a 30% markup is not a 30% margin
Use the right denominator, convert between the two percentages, and check a selling price against a target gross margin.
How to Calculate Tax Percentages
If a single known rate r applies to the whole taxable amount B, tax = B × r / 100 and total = B × (1 + r / 100).
Interest percentages: simple interest, compounding and annual rates
For simple interest, I = P × r × t, where r is the annual rate as a decimal and t is years.
Methods & data
Convert fractions, decimals and percentages in all six directions
A fraction a/b becomes a decimal by dividing a by b, and a percentage by multiplying that ratio by 100.
Percentages in statistics: counts, weighted rates and percentage points
A percentage needs a numerator and a defined denominator: part ÷ whole × 100.
Percentage increases and decreases: apply and compare changes
To change an amount B by p%, multiply B by 1 + p/100 for an increase or 1 − p/100 for a decrease.
Percentage Change Formula Explained
Master the percentage change formula with step-by-step examples, common pitfalls to avoid, and real-world applications.
What is a Percentage? A Complete Guide
Learn what percentages are, how they work, and how to calculate them with practical examples from everyday life.