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Percentage Calculator

Calculate percentages, percentage changes, and reverse percentages.

What is X% of Y?
% of= -
X is what percentage of Y?
is what % of= -
Percentage change from X to Y
to= -
Increase / Decrease X by Y%
by%
Increased: -
Decreased: -
X is P% of what number? (Reverse)
is% of = -

What does this tool do?

Percentage questions come up constantly — calculating a tip, working out a discount, figuring out how much a price increased, or checking your grade on a test. There are three common types of percentage problems, and people confuse them with each other all the time. This tool handles all three: finding a percentage of a number (what is 15% of $85?), expressing one number as a percentage of another (80 is what % of 200?), and calculating percentage change between two values (how much did revenue grow?).

How to use it

  1. Select the type of problem you are solving from the three options.
  2. Enter the numbers.
  3. The answer appears instantly — no formula needed.

Pro tips

  • For percentage change, the formula is (new − old) ÷ old × 100. A drop from 100 to 50 is −50%, but a rise from 50 back to 100 is +100% — they are not symmetric.
  • A 50% increase followed by a 50% decrease does not bring you back to the start — it leaves you 25% lower than where you began.
Example

Problem 1: What is 15% of $85? | Problem 2: 47 out of 60 is what percent? | Problem 3: Revenue went from $10,000 to $12,500 — what was the growth?

Answer 1: $12.75 (your restaurant tip)
Answer 2: 78.3% (your test score)
Answer 3: 25% growth

When would you use this?

  • Calculating a restaurant tip (15–20% of the total bill)
  • Working out the final price after a 30% discount
  • Figuring out what percentage a test score represents (e.g. 47 out of 60)
  • Calculating month-over-month or year-over-year revenue growth
  • Understanding how much a price has increased in percentage terms