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Percentage Calculator

Calculate percentages, percentage changes, increases, decreases, and solve percentage problems

Calculation Type

Select the type of percentage calculation you need

Basic Percentage

The part or portion
The total or whole amount

Result

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Select calculation type and enter values
Your percentage result will appear here

How It's Calculated

Quick Examples

Basic Percentage
25 is what % of 100?
25%
Percentage Change
From 100 to 120
+20% increase
Percentage Increase
100 + 15%
115
Percentage Decrease
100 - 10%
90
What % Of
50 is what % of 200?
25%
What Is % Of
What is 20% of 150?
30
Click any example to load the values and see the calculation

Understanding Percentages

What Are Percentages?

Percentages are just a fancy way of saying "out of 100". The word literally means "per hundred" - so when you see 25%, you're looking at 25 out of every 100. It's like having a universal language for comparing things, whether you're talking about test scores, discounts, or how much of your salary gets eaten by taxes.

Think of it this way: if percentages didn't exist, you'd have to say "I got 17 questions right out of 20" versus "I got 85%". Much easier to compare an 85% with a 92%, right?

The Basic Maths Behind It

Don't worry, the maths is simpler than it looks:

  • To find a percentage: (Part ÷ Whole) × 100
  • To find the part: (Percentage ÷ 100) × Whole
  • To find the whole: Part ÷ (Percentage ÷ 100)

Percentage Changes (The Tricky One)

This is where people often get confused. When something goes from £100 to £120, that's not a 20% increase of £120 - it's a 20% increase of the original £100.

The formula is: ((New Value - Old Value) ÷ Old Value) × 100. If it's positive, it's an increase. If it's negative, it's a decrease. Simple as that.

Different Types of Calculations

Our calculator handles six main types because, let's face it, percentage problems come in all shapes and sizes:

  • Basic %: What percentage is 25 of 100? (Answer: 25%)
  • % Change: From £80 to £100 = 25% increase
  • % Increase: £100 + 20% = £120
  • % Decrease: £100 - 20% = £80
  • What % of: 25 is what % of 100? (25%)
  • What is % of: What is 25% of 100? (25)

Real-World Examples

Here's where percentages actually matter in your daily life:

  • Shopping: That £80 jacket with 25% off costs £60
  • Salary raise: £50k with a 5% raise becomes £52.5k
  • Restaurant tip: 15% on a £40 bill = £6 tip
  • Test scores: 42 out of 50 questions = 84%
  • Interest rates: 3.5% annual rate on your savings
  • VAT: 20% on most purchases in the UK

Quick Mental Tricks

Want to impress people with your percentage skills?

  • 50%: Just divide by 2
  • 25%: Divide by 4
  • 10%: Move the decimal point one place left
  • 1%: Move the decimal point two places left
  • 15% tip trick: Take 10% and add half of that
  • Double-check: Your percentage + what's left should equal 100%