Percentage Calculator
Three calculators in one: find X% of a number, what percent X is of Y, and percentage change.
Tip: results update as you type. Percentage change uses the original value as the base — the standard method used in finance and statistics.
About this tool
Percentages show up everywhere — a 12% discount at checkout, an 18% GST line on an invoice, a marks percentage on a report card, a salary hike, a mutual fund return. But there are actually three different percentage questions, and using the wrong formula gives the wrong answer. This calculator handles all three, side by side, so you always pick the right one.
The first finds a percentage of a number — what is 15% of 2,400? (360). The second works in reverse — 45 is what percent of 180? (25%). The third calculates percentage change between two values — from 80 to 92 is a 15% increase — using the original value as the base, the standard method in finance and statistics.
All three update live as you type, with no Calculate button to press. Results are precise to two decimal places, and the change calculator labels increases and decreases explicitly, so a drop from 92 to 80 reads clearly as a decrease rather than a confusing negative number. Everything runs in your browser: instant, private, and available offline once loaded.
How to use the Percentage Calculator
- 1Pick the row that matches your question — percent of a number, reverse percentage, or percentage change.
- 2Type your numbers into the boxes. Results appear instantly as you type.
- 3For percentage change, enter the original value first and the new value second.
- 4Read the result on the right — increases and decreases are labelled automatically.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 15% of 2,400 = (15 ÷ 100) × 2,400 = 360. The first row of the calculator does this automatically.
How is percentage change calculated?
Percentage change = (new value − original value) ÷ original value × 100. Going from 80 to 92 is (92 − 80) ÷ 80 × 100 = 15% increase. The original value is always the base — this is the standard convention in finance and statistics.
Why is a percentage increase then decrease not symmetric?
Because the base changes. A 50% increase on 100 gives 150, but a 50% decrease from 150 gives 75, not 100. Each change is calculated relative to its own starting value.
Can I use this for discounts and GST?
Yes. For a discount, calculate the percentage of the price and subtract it. For GST, calculate the percentage and add it. For example, 18% GST on ₹1,000 = ₹180, making the total ₹1,180.