How to use the Percentage Calculator
- Pick the card that matches your question.
- Type the two numbers in the boxes.
- The answer appears instantly at the bottom of the card. For percentage change, the card also tells you whether it is an increase or a decrease.
Formula
X% of Y = X × Y ÷ 100
X as % of Y = X ÷ Y × 100
% change = (New − Old) ÷ Old × 100
- To increase a number by X%, multiply it by (1 + X/100). To decrease it, multiply by (1 − X/100).
Worked example: Marks, salary hikes and price changes
Marks: you scored 432 out of 500. 432 ÷ 500 × 100 = 86.4%.
Salary hike: your salary rose from ₹40,000 to ₹46,000. (46,000 − 40,000) ÷ 40,000 × 100 = 15% increase.
Discount: 15% of ₹2,000 = ₹300.
Percentage points vs percent
If an interest rate goes from 8% to 10%, it has risen by 2 percentage points, but by 25 percent (2 ÷ 8 × 100). News reports and loan offers often mix these up, so check which one is meant.
Why a 10% rise and a 10% fall don’t cancel out
If ₹100 rises by 10% it becomes ₹110. If ₹110 then falls by 10%, it becomes ₹99 – not ₹100. The second change is calculated on a bigger base. Use the percentage-change card to see the exact effect of back-to-back changes.