Percentage Calculator

Six handy percentage calculators — pick the one you need

What is X% of Y?

Percentage (%)

% of

Number

X is what % of Y?

Value (X)

Total (Y)

Percentage Change (Increase / Decrease)

Original Value

New Value

Add or Remove a Percentage

Number

Operation

Percentage (%)

Find Original Value (Reverse %)

Given final value after a % increase or decrease, find the original.

Final Value

Was changed by (%)

After Increase After Decrease

Percentage Difference Between Two Values

Symmetric difference — neither value is treated as the "original".

Value A

Value B

Frequently Asked Questions

Divide the part by the whole and multiply by 100. Formula: (X ÷ Y) × 100. Example: 80 is what % of 200? → (80 ÷ 200) × 100 = 40%.

Formula: ((New − Original) ÷ Original) × 100. Example: price went from 100 to 150 → ((150 − 100) ÷ 100) × 100 = 50% increase.

Percentage change has a clear "before" and "after" — it shows how much a value changed relative to the original. Percentage difference is symmetric — it compares two values without either being the reference point, using their average as the denominator: |A − B| ÷ ((A + B) / 2) × 100.

Use the "Find Original Value" calculator (calculator 5). If a product now costs ₹850 after a 15% discount, the original was ₹850 ÷ (1 − 0.15) = ₹1,000. Formula: Final ÷ (1 − discount%/100).

Multiply the number by (1 + percentage/100). Example: add 18% GST to ₹1,000 → 1000 × 1.18 = ₹1,180. To remove a percentage: multiply by (1 − percentage/100). Example: remove 18% from ₹1,180 → 1180 ÷ 1.18 = ₹1,000.

100% of any number equals the number itself (the whole thing). 50% = half. 200% = double. Percentages above 100 mean the result is greater than the original. For example, 150% of 200 = 300.

These are easily confused. If an interest rate rises from 5% to 8%, it increased by 3 percentage points (an absolute difference). But in percentage terms, it increased by 60% ((8−5)/5 × 100). Percentage points measure absolute changes between two percentage values, while percentage change measures the relative change. In financial news, central bank rate hikes are always described in percentage points (e.g., "raised by 25 basis points = 0.25 percentage points").

Markup is the profit as a percentage of cost: Markup% = (Profit ÷ Cost) × 100. Margin is the profit as a percentage of selling price: Margin% = (Profit ÷ Selling Price) × 100. A product costing $80 sold for $100 has a markup of 25% but a margin of 20%. Retail businesses commonly confuse these — a 50% markup is only a 33.3% margin. Always clarify which base is being used when discussing profit percentages.

Useful mental shortcuts: (1) 10% of any number — move the decimal one place left (10% of 350 = 35). (2) 5% = half of 10% (5% of 350 = 17.5). (3) 15% = 10% + 5% (35 + 17.5 = 52.5). (4) X% of Y = Y% of X — for example, 7% of 50 = 50% of 7 = 3.5 (easier to compute). (5) 25% = divide by 4; 33.3% = divide by 3; 20% = divide by 5.

The formula is: Percentage Change = ((New Value − Original Value) ÷ |Original Value|) × 100. A positive result means an increase; a negative result means a decrease. Example: price dropped from $250 to $180 → ((180 − 250) ÷ 250) × 100 = −28% (a 28% decrease). Never use the new value as the denominator — always use the original (starting) value to correctly represent the direction and magnitude of change.

About This Percentage Calculator

This free Percentage Calculator covers six common percentage problems — all calculated instantly in your browser. Whether you need to find a percentage of a number, calculate how much prices changed, reverse-calculate an original value, or compare two numbers, this tool has you covered.

Calculator	Formula	Example
X% of Y	(X / 100) × Y	20% of 500 = 100
X is what % of Y	(X / Y) × 100	80 is 40% of 200
% Change	((New − Old) / Old) × 100	100→150 = +50%
Add %	N × (1 + P/100)	1000 + 18% = 1180
Remove %	N × (1 − P/100)	1180 − 18% ≈ 967.6
Reverse %	Final / (1 ± P/100)	1180 after +18% → orig = 1000
% Difference	\|A−B\| / ((A+B)/2) × 100	\|80−120\| / 100 × 100 = 40%

Standards & References

Wikipedia — Percentage

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