Percentage Calculator
Work out percentages, increases, decreases and what-of-what — three calculators in one.
What is the Percentage Calculator?
The Percentage Calculator is a three-in-one tool that answers the most common percentage questions you run into every day: "What is 20% of 150?", "40 is what percentage of 180?" and "What is the percentage change from 80 to 100?". Choose a mode, type your numbers and get an instant, rounded, easy-to-read result.
Percentages hide inside almost every calculation — sales tax, tips, discounts, exam marks, salary hikes, statistics. Doing them in your head is doable but error-prone; using a general calculator means remembering the exact formula. This tool removes both problems and shows the answer as soon as you finish typing.
Every calculation happens in your browser. Salaries, exam scores, personal budgets and business figures never leave your device, which matters when you punch in real numbers instead of round examples.
How to use the Percentage Calculator
- 1Open the Percentage Calculator page and pick a mode from the tabs at the top.
- 2For "X% of Y", enter the percentage in the first field and the amount in the second.
- 3For "A is what % of B", enter the partial value (A) and the total value (B).
- 4For "% change", enter the original value and the new value to see the increase or decrease.
- 5Read the result immediately below the inputs — no button click needed.
- 6Adjust any number to instantly see the new result.
Key features
- Three modes: percent-of, is-what-percent-of, percent-change
- Live recalculation on every keystroke
- Handles negative changes (decreases show as negative %)
- Rounded to four decimal places for readability
- Works with any currency and any unit
- Runs completely offline in your browser
- No sign-up, no ads inside the calculator
Examples
Sale price
A ₹1,200 shirt marked 25% off ⇒ 25% of 1,200 = ₹300 discount, so the sale price is ₹900.
Exam score
Scoring 68 out of 90 in an exam ⇒ 68 is 75.56% of 90.
Salary hike
Salary going from ₹80,000 to ₹92,000 ⇒ a 15% increase.
Why use this tool
- Removes mental-math errors
- Works for both increases and decreases
- Three related calculators in a single URL
- Great for shopping, exams, budgeting and statistics
- Free and private — nothing uploaded
Common use cases
- Working out sale discounts before checkout
- Calculating tips at restaurants
- Converting exam marks to percentages
- Estimating salary hikes and appraisals
- Understanding stock-price changes
- Modelling percentage-based commissions
Frequently asked questions
How do I calculate a percentage increase?
Use the "% change" mode. Enter the original value in the first box and the new value in the second — positive means increase, negative means decrease.
Can I use negative numbers?
Yes — negative inputs are supported. Percentage change will still tell you the correct direction.
How is the calculation done?
For X% of Y: (X ÷ 100) × Y. For A of B: (A ÷ B) × 100. For change: ((new − old) ÷ old) × 100.
Are my inputs uploaded?
No. All maths happens in your browser.
Does the tool support very large numbers?
Yes — up to JavaScript’s safe integer limit (~9 × 10¹⁵). Beyond that, expect precision loss.