How do I calculate what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example, 30 is what percent of 120? (30 / 120) x 100 = 25%. The calculator handles this automatically — enter the two numbers in the 'X is what % of Y?' section.

How do I calculate a percentage increase or decrease?

Percentage change = ((new value - old value) / old value) x 100. A positive result is an increase; negative is a decrease. For example, price went from $80 to $100: ((100 - 80) / 80) x 100 = 25% increase.

How do I find the original value before a percentage was applied?

Original = final value / (1 + percentage/100) for increases, or final value / (1 - percentage/100) for decreases. If a price is $90 after a 10% discount: 90 / (1 - 0.10) = 90 / 0.90 = $100 original price.

What is the difference between percentage points and percent?

Percentage points measure the arithmetic difference between two percentages. If interest rates go from 2% to 5%, that is a 3 percentage point increase, but a 150% relative increase. These are very different things — be careful which one is being reported.

How do I calculate compound percentage growth?

For compound growth over multiple periods, use: final = initial x (1 + rate)^periods. For example, 5% annual growth over 3 years: 1000 x (1.05)^3 = $1,157.63. Use the Compound Interest Calculator for more detailed compound growth calculations.

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% Percentage Calculator — 3 Calculators in One

Enter any two numbers to instantly calculate a percentage — no formulas, no button clicks. Find X% of a number, calculate a ratio, or work out percentage change. This free percent calculator provides instant results as you type.

Last updated: June 2026

What is X% of Y?

e.g. What is 15% of $84? → $12.60

What is % of

X is what % of Y?

e.g. 43 out of 50 marks → 86%

is what % of

25%

% Increase / Decrease

e.g. Price from $80 → $100 → 25% increase

From To

20% increase

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