What is the Percentage?
Percentages appear in every financial decision — discounts, interest, returns, tax and salary hikes. The three that cause the most confusion are percentage of, percentage change, and reverse percentage (working backwards from a result).
Formula & worked example
Change = (B − A) / A × 100
A as % of B = A / B × 100
Reverse: if A is X% of N, then N = A / (X / 100)
Worked example: 15% of ₹2,500 is ₹375. Going from ₹2,500 to ₹3,200 is a 28% increase. And ₹2,500 is 78.1% of ₹3,200. Working backwards, if ₹2,500 is 15% of something, that something is ₹16,667.
How to use this percentage calculator
- Enter Value A as your base number.
- Enter Value B to compare against A.
- Enter the percentage you want to apply.
- All six results appear in the table below.
Smart tips
- A percentage increase followed by the same percentage decrease never returns you to the start — +20% then −20% leaves you 4% down.
- Percentage change always uses the original value as the denominator, not the new one.
- Percentage points and percent are different: moving from 5% to 7% is a 2 percentage point rise but a 40% increase.
- For reverse GST or discount calculations, divide rather than multiply — a common and costly error.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. 15% of 2,500 is 2,500 × 15 / 100 = 375.
How do I calculate percentage increase?
Subtract the old value from the new, divide by the old value, and multiply by 100.
What is a reverse percentage?
Working backwards from a result. If ₹2,500 is 15% of a total, the total is 2,500 / 0.15 = ₹16,667.
Why does +20% then −20% not return to the original?
Because the decrease applies to the larger number. ₹100 → ₹120 → ₹96, a net 4% loss.
Want the theory behind the numbers? Read our money basics on the Money Blog.
Written by Gurjeet Singh, Sharpen Solutions. Last reviewed 30 Sep 2026. How we check these numbers.