Percentage Calculator
Three of the most common percentage questions, each as its own live calculator. Type into any field and the answer updates instantly.
What is X% of Y?
15% of 200 is 30.
X is what % of Y?
20 is 25% of 80.
% change from X to Y
50 to 40 is a 20% decrease.
Results and any AI-generated content from this tool are provided free, "as is", for general informational purposes only and may be inaccurate, incomplete, or out of date. Always verify the output yourself before relying on it — you use this tool and its results at your own risk.
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Three percentage questions, one page
Percentages come up constantly in business — discounts, margins, commission, GST, growth targets — but the actual question you're asking usually falls into one of three shapes. This calculator handles all three as separate, always-visible cards, so you never have to remember which formula goes with which question: "what is X% of Y" for discounts and commissions, "X is what % of Y" for working out a ratio or a pass rate, and "% change from X to Y" for comparing two numbers over time — last month's sales versus this month's, for example.
Every result updates as you type, is trimmed to a sensible number of decimal places (no "30.00000000001" from floating-point rounding), and handles negative numbers and zero correctly — dividing by zero shows a friendly message instead of a broken "Infinity" or "NaN" on the page.
Worked examples
What is X% of Y: 15% of 200 = 30 — useful for calculating a discount amount or a commission on a sale.
X is what % of Y: 20 is what % of 80 = 25% — useful for figuring out what share one number is of another, like units sold out of total stock.
% change from X to Y: from 50 to 40 = −20% (a decrease) — useful for tracking whether a number went up or down, and by how much, in percentage terms rather than raw units.
Where small businesses use percentage math
Indian small business owners use percentage calculations daily — working out a festive discount, checking whether a vendor's price increase is reasonable, or seeing month-over-month growth in orders or footfall. Pair this with the GST Calculator for tax-specific percentage math, or browse all free tools for more.
Once your numbers are sorted, put your pricing, offers, and contact details on a free BizGo business page so customers can find them in one place — see the box above to get started.
Frequently Asked Questions
Multiply Y by X and divide by 100. For example, 15% of 200 is (15 ÷ 100) × 200 = 30. Use the first card above and just type in the two numbers.
Divide the first number by the second, then multiply by 100. For example, 20 is (20 ÷ 80) × 100 = 25% of 80. Use the second card above.
Percent change = ((new value − old value) ÷ old value) × 100. Going from 50 to 40 is ((40 − 50) ÷ 50) × 100 = −20%, a 20% decrease.
The calculator shows a friendly message instead of an error — you can't calculate "X is what % of 0" or a percent change starting from 0, since both require dividing by zero.
Yes — all three modes accept negative inputs and show the correctly signed result (e.g. a negative percent change for a decrease).
