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Percentage Calculator

Percent of a number, marks percentage, percent change, increase or decrease by a percent, and more, with the working shown.

Runs in your browserNo sign-up required
What is% of?
30

= 20 × 150 ÷ 100 = 30

is what % of?
86.4%

= 432 ÷ 500 × 100 = 86.4%

is% of what?
300

= 45 × 100 ÷ 15 = 300

% change fromto
+25%an increase of 200

= (1,000 − 800) ÷ 800 × 100 = 25%

Increaseby%
27,5002,500 added

= 25,000 × (1 + 10 ÷ 100) = 27,500

Decreaseby%
1,499.25499.75 off

= 1,999 × (1 − 25 ÷ 100) = 1,499.25

% difference betweenand
22.2222%

= |120 − 150| ÷ average(120, 150) × 100 = 22.2222%

Three Percentage Problems, One Calculator

Most “percentage calculator” searches actually fall into one of three different questions that get mixed up with each other constantly — finding a percentage of a number, working out what percent one number is of another, and calculating the percent increase or decrease between two values. Each one uses a different formula, which is exactly why plugging numbers into the wrong version gives an answer that looks plausible but is completely wrong. This tool separates the three clearly with a switch at the top, so you calculate the one you actually need.

Worked Examples

  1. 1"What is 18% of 2,450?"Use the first card: 18 × 2,450 ÷ 100 = 441. Handy for tips, discounts or tax amounts.
  2. 2"I scored 432 out of 500. What is my percentage?"Use "… is what % of …?" with 432 and 500: 86.4%. The same card works for survey results or any "how much of the total" question.
  3. 3"A price went from ₹800 to ₹960. What is the increase?"Use "% change from … to …": +20%, an increase of ₹160. A fall shows in red with a minus sign, so you don't need to remember which number goes on top.
  4. 4"My salary of ₹25,000 goes up by 10%."Use "Increase … by … %": ₹27,500, with ₹2,500 added.

How to Use This Calculator

  1. 1Find the card that matches your questionEach card is written as a question, such as "What is 20% of 150?" or "% change from 800 to 1000".
  2. 2Type your numbers into the boxesThe answer updates as you type. Decimals and negative numbers work.
  3. 3Check the working and copyUnder each answer you can see the exact sum used. Tap the copy icon to copy the question and its answer.

Common Mistakes to Avoid

  • Mixing up "percent of" with "percent change" — a value going from 50 to 75 is a 50% increase, not "75% of 50," which is a completely different calculation.
  • Forgetting that percent change is not symmetric — going from 100 to 50 is a 50% decrease, but going back from 50 to 100 is a 100% increase, not 50%.
  • Rounding too early in a multi-step calculation — small rounding errors early on can compound into a noticeably wrong final answer.
  • Confusing percentage points with percent — going from 20% to 25% is a 5 percentage point increase, but a 25% relative increase in the original rate.

The Three Formulas

X% of Y = (X / 100) × Y
X is what % of Y = (X / Y) × 100
% change from X to Y = ((Y − X) / |X|) × 100

Examples: 20% of 150 = 30.  20 as a % of 150 ≈ 13.33%.  Going from 20 to 150 is a +650% change (and from 150 to 20 would be about −86.7%).

A negative result in the "% change" card means a decrease — going from 150 to 20, for instance, gives a negative percentage even though both numbers are positive.

Frequently Asked Questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For 18% of 2,450: (18 × 2450) ÷ 100 = 441. The first card, "What is … % of …?", does exactly this.

How do I find what percent one number is of another?

Divide the first number by the second, then multiply by 100. For "45 out of 60": (45 ÷ 60) × 100 = 75%. Use the "… is what % of …?" card.

How is percent increase or decrease calculated?

Subtract the original value from the new value, divide by the original value, then multiply by 100. A negative result means a decrease. The "% change from … to …" card does this in either direction and shows whether it is an increase or a decrease.

Why isn't percent change symmetric — why does going up and back down not cancel out?

Because percent change is always relative to the starting number, and that starting number is different depending on which direction you're calculating. A 50% increase from 100 gets you to 150, but a 50% decrease from 150 only brings you back to 75, not 100 — the base amount shrank in between.

How do I calculate my marks percentage?

Divide the marks you got by the total marks and multiply by 100. For 432 out of 500: 432 ÷ 500 × 100 = 86.4%. Use the "is what % of" card.

How do I find the original number from a percentage?

If 45 is 15% of a number, the number is 45 × 100 ÷ 15 = 300. The "is … % of what?" card does this, for example to find a full price from a known discount amount.

How do I add or take off a percentage?

To increase by a percentage, multiply by (1 + % ÷ 100): ₹25,000 + 10% = ₹27,500. To decrease, multiply by (1 − % ÷ 100): ₹1,999 − 25% = ₹1,499.25. The increase and decrease cards also show how much was added or taken off.

What is the difference between percentage change and percentage difference?

Percentage change compares a new value with an old one, so the order matters (800 → 1,000 is +25%, 1,000 → 800 is −20%). Percentage difference compares two values without a before and after, dividing the gap by their average: 120 and 150 differ by about 22.22%.

Does this calculator handle negative numbers or decreases?

Yes — the % change card shows a negative percentage for any decrease, and every card accepts decimals and negative numbers.

Is this percentage calculator free to use?

Yes, completely free, with no account needed, and it runs entirely in your browser.