Percentage Calculator
Quickly find what percent one number is of another, calculate percentage change, and understand discounts or markups in seconds.
✅ Free online tool ✅ Mobile-friendly ✅ Great for finance, exams & shopping
Calculate what percent the part is of the whole
How to Use the Percentage Calculator
This Percentage Calculator is designed to make everyday math easy. Simply enter the part (the portion you are interested in) and the whole (the total value), then click Calculate %. The tool instantly shows you what percentage the part is of the whole.
- Shopping & discounts: Check how much you save or pay after a discount.
- Finance & tax: See what percent of income goes to EMI, rent, savings, or tax.
- Exams & grades: Convert raw marks into percentage scores.
- Business & data: Compare performance, growth or share of total sales.
Percentage Formula
A percentage is a way of expressing a number as a fraction of 100. The basic formula is:
Percentage (%) = (Part / Whole) × 100
Example 1 – Exam score
You scored 72 marks out of 90. The percentage is:
(72 ÷ 90) × 100 = 80%
Example 2 – Expense ratio
Your rent is $600 out of a $2,000 monthly income. The percentage of
income spent on rent is:
(600 ÷ 2000) × 100 = 30%
Percentage Increase and Decrease
Percentage change tells you how much a value has grown or declined relative to its original value.
Percentage Change (%) = ((New − Old) / Old) × 100
Example – Price increase
A product goes from $50 to $65:
((65 − 50) ÷ 50) × 100 = 30% increase.
Note that a 30% increase and a 30% decrease are not symmetric. If the price falls by 30% from $65, the new price is 65 × (1 − 0.30) = $45.5, not $50.
Percentage Calculator – FAQs
How do I calculate a percentage?
Divide the part by the whole and multiply the result by 100. For example, (20 ÷ 80) × 100 = 25%.
Can I use this calculator for discounts and GST?
Yes. You can enter the discount or tax amount as the part and the original price as the whole to understand what percent it represents.
Is percentage change the same as difference in percent?
No. Percentage change is based on the original value. A 20% increase followed by a 20% decrease does not bring you back to the exact starting value.
What happens if I enter zero as the whole?
The whole cannot be zero, because division by zero is undefined. The calculator will ask you to enter a non-zero whole value.
Can I enter decimal or negative numbers?
Yes. Decimal values give more precise percentages, and negative numbers can represent losses, drops, or reversed changes in many finance and data contexts.