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What is a Percentage Calculator?
A Percentage Calculator is a multi-mode tool that solves the three percentage problems people run into most often: figuring out what percentage one number represents of another, working out a percentage of a given value, and measuring how much a number has increased or decreased in percentage terms. Instead of switching formulas in your head, you simply pick the mode you need from the dropdown and enter your two numbers.
The Three Calculation Modes
Mode 1 — "What % is A of B?"
Use this when you know two numbers and want to express the first as a percentage of the second — for example, marks scored out of total marks.
Example: A = 456, B = 600 → (456 ÷ 600) × 100 = 76%
Mode 2 — "What is X% of Y?"
Use this when you already know a percentage rate and want to find the actual value it represents — for example, a bank interest rate applied to a deposit.
Example: X = 8%, Y = ₹1,00,000 → (8 ÷ 100) × 1,00,000 = ₹8,000
Mode 3 — "% Change from Old to New"
Use this to measure growth or decline between two values, such as a salary revision or a change in monthly expenses.
Example: Old = ₹40,000, New = ₹46,000 → ((46,000 − 40,000) ÷ 40,000) × 100 = 15% increase
If the new value is smaller than the old value, the result is shown as a percentage decrease instead — the calculator automatically labels the direction of change based on the sign of the result.
How to Use This Percentage Calculator
- Choose a calculation type from the dropdown: "What % is A of B", "What is X% of Y", or "% Change from Old to New".
- Fill in the two number fields that appear for the selected mode.
- Click Calculate to see the result along with a plain-language explanation of what it means.
Common Real-Life Uses in India
- Exam and marksheet percentages: Scored 456 out of 600 in board exams? Use Mode 1 to instantly get 76%.
- Shopping discounts: A ₹2,500 jacket at "30% off" — use Mode 2 to find the exact amount knocked off before checkout.
- Salary or fee hikes: Compare your old and new salary, rent, or school fee using Mode 3 to see the exact percentage jump.
- Investment returns: Check how much a mutual fund or FD investment has grown in percentage terms between two dates.
- Tax and GST context: Percentages sit behind every GST slab and TDS rate — for the specific CGST/SGST split and add/remove-GST workflow, see our dedicated GST Calculator.
Looking specifically for a shopping discount breakdown? Try the Discount Calculator. Need to average a list of numbers instead? Use the Average Calculator.
Who Should Use This Percentage Calculator?
This tool is built for anyone who runs into percentages in daily life rather than just a classroom. School and college students use Mode 1 to convert marks into percentages the moment a report card lands, and to reverse-check what raw score a required percentage cutoff corresponds to. Retail shoppers and small business owners lean on Mode 2 to work out discounts, markups, and GST-inclusive pricing before a sale closes. HR teams and employees use Mode 3 to compare old and new salary figures during appraisal season, while landlords and tenants use the same mode to check rent hikes against local norms. Investors and mutual fund holders use percentage change to track portfolio growth between two NAV dates, and researchers use it to express survey results and growth rates in a form that's easy to compare across different sample sizes.
Common Mistakes to Avoid
The biggest error is treating successive percentage changes as additive. A 20% discount followed by an extra 10% off at checkout is not 30% off — the second discount applies to the already-reduced price, so ₹1,000 → ₹800 → ₹720, a combined 28% discount, not 30%. The same logic applies to salary hikes: an 8% raise followed by a 5% raise the next year is not a 13% total increase, since the second raise is calculated on the already-increased base. Another frequent slip is confusing percentage increase with percentage of the new value — going from ₹400 to ₹500 is a 25% increase over the old value, but ₹100 is only 20% of the new value; using the wrong base flips the answer. Finally, always check which number is the "base" in Mode 1 and Mode 3 — swapping A and B, or Old and New, gives a mathematically valid but wrong-context answer.
Frequently Asked Questions
Q: Can a percentage be more than 100%?
A: Yes. Percentages describe a ratio, not a capped scale, so any time the numerator is larger than the base, the result exceeds 100%. For example, if profit grew from ₹2 lakh to ₹5 lakh, the new profit is (5÷2)×100 = 250% of the old profit — a 150% increase.
Q: What's the difference between a percentage change and a percentage point change?
A: A percentage point (pp) change is a simple subtraction between two percentage figures, while a percentage change measures the relative change between them. If an interest rate moves from 5% to 8%, that's a 3 percentage point increase, but a (8-5)/5×100 = 60% increase — the two describe different things and are often confused in news reports.
Q: How do I find the original price before a discount was applied?
A: Use Mode 2 in reverse: if a discounted price is ₹850 after a 15% discount, the original price equals discounted price ÷ (1 - discount rate) = 850 ÷ 0.85 = ₹1,000. This calculator's Mode 2 directly finds X% of Y, but reversing it just needs this one extra division step.
Q: Why do I get a negative result in Mode 3?
A: Mode 3 automatically labels the result as an increase or decrease based on whether the new value is higher or lower than the old value. A negative percentage change simply means the new value is smaller — for example, going from ₹500 to ₹400 is a (400-500)/500×100 = -20%, shown as a 20% decrease.
Q: How is percentage used for calculating exam cutoffs in India?
A: Most Indian boards and competitive exams (SSC, banking, UPSC) publish cutoffs as a percentage of total marks. Using Mode 1, entering your marks scored as Value A and total marks as Value B instantly tells you whether you've crossed a published cutoff, without needing to convert manually.
Q: Do two discounts of 20% and 10% add up to 30% off?
A: No — successive discounts multiply, not add. 20% off followed by 10% off the reduced price gives a combined 28% discount, not 30%, since the second cut applies to a smaller base.
📅 Last reviewed: July 2026 · Formulas verified against RBI/SEBI/IT Dept guidelines.