Percentage Calculator
Stop struggling with manual formulas. Select your calculation mode below to instantly find proportions, percentage increases, and basic fractional values.
How to Calculate Percentage: The Complete Mathematical Guide
Calculating percentages is a fundamental real-world skill, yet it remains one of the most heavily searched mathematical equations globally. Whether you are trying to figure out a sales tax deduction, calculate a discount on a retail purchase, or determine your academic grade standing, understanding the underlying formula is essential.
Our free percentage calculator automates the math, but the standard universal formula is: Percentage = (Part / Whole) × 100.
1. The Basic Percentage (What is X% of Y?)
This is the most common use case. For example, if you want to leave a 20% tip on a $85 restaurant bill, you need to find out what 20% of 85 is. To do this manually, convert the percentage to a decimal by dividing by 100 (20 / 100 = 0.20). Then, multiply that decimal by the total amount (0.20 × 85 = 17). Your tip is $17.
2. Finding Proportions (X is what % of Y?)
This calculation is crucial for academics and business analytics. If you scored 45 out of 60 on a test, what is your percentage? Using the proportion formula, you divide the partial amount by the total amount, and multiply by 100. (45 / 60 = 0.75). Multiply by 100 to get 75%.
3. Percentage Increase & Decrease
Tracking percentage change is mandatory for tracking financial investments, business revenue, or weight loss. To calculate a percentage increase or decrease, you use the formula: (New Value - Old Value) / |Old Value| × 100.
For example, if your rent was $1,500 last year and is $1,650 this year, the math is: (1650 - 1500) / 1500 = 0.10. Multiply by 100, and you see that you have experienced a 10% rent increase.
