%

Percentage Calculator

Solve 6 types of percentage problems instantly: find a percentage, percentage change, percentage of total, increase/decrease, and reverse percentage.

6 Calculation Types⚡ Instant

% Percentage Calculator

Results update instantly

What is X% of Y?
%
of
= 30
X is what % of Y?
is what % of
= 15%
Percentage Change
→ new value →
= +25%
Increase/Decrease by %
%
+Increase
−Decrease
= 240

Percentage Formulas — All Types Explained

Percentages appear everywhere in everyday life: discounts, tax rates, interest rates, grade calculations, statistics, and financial analysis. Here are the core formulas:

📐 Core Percentage Formulas

X% of Y = (X ÷ 100) × Y
X of YPercentage of a number: (X/100) × Y
X is %What % is X of Y: (X ÷ Y) × 100
Change% change: ((New − Old) ÷ Old) × 100
ReverseOriginal value: Amount ÷ (1 + rate)

Frequently Asked Questions

Multiply the number by 0.20 (or divide by 5). For example, 20% of $150 = $150 × 0.20 = $30. A quick mental trick: find 10% (move decimal one place left), then double it.
Subtract the old value from the new value, divide by the old value, and multiply by 100. Formula: ((New − Old) ÷ Old) × 100. If the result is positive, it is an increase; if negative, a decrease.
Use reverse percentage: Original = Sale price ÷ (1 − discount%). For example, if an item costs $80 after a 20% discount: Original = $80 ÷ 0.80 = $100.
Divide the part by the whole, then multiply by 100. Example: 45 is what percent of 180? 45 ÷ 180 = 0.25 × 100 = 25%. Alternatively: (Part ÷ Whole) × 100 = Percentage. This is the most common percentage calculation in everyday use — tips, discounts, tax, and grade calculations all use this formula.
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. If a price goes from $80 to $100: (($100 − $80) ÷ $80) × 100 = 25% increase. If it goes from $100 to $80: (($80 − $100) ÷ $100) × 100 = −20% decrease. Note: a 25% increase followed by a 20% decrease does not return to the original value.
⚠️ Disclaimer Estimates for informational purposes only. Not legal or financial advice. Consult a qualified professional.

How to Calculate a Percentage — 3 Core Methods

Percentage calculations fall into three main categories that cover almost every real-world situation. Understanding each formula makes mental math faster and helps you verify calculator results.

Method 1: What is X% of Y?

Formula: Result = (X ÷ 100) × Y
Example: What is 15% of $85 (restaurant tip)? = (15 ÷ 100) × 85 = $12.75

Method 2: What percentage is X of Y?

Formula: Percentage = (X ÷ Y) × 100
Example: You scored 43 out of 60 on a test. What percentage? = (43 ÷ 60) × 100 = 71.7%

Method 3: Percentage Change (Increase or Decrease)

Formula: % Change = ((New Value − Old Value) ÷ Old Value) × 100
Example: Price went from $80 to $92. Percentage increase? = ((92 − 80) ÷ 80) × 100 = 15% increase

Percentage Increase vs Percentage Point Increase

These are often confused. If interest rates go from 2% to 3%, that's a 1 percentage point increase but a 50% increase in the rate itself. Percentage points describe absolute change in a percentage value; percentages describe relative change. This distinction matters enormously in finance, statistics, and politics.

Quick Mental Percentage Tricks

  • 10%: Move the decimal point one place left. 10% of $347 = $34.70
  • 5%: Half of 10%. 5% of $347 = $17.35
  • 20%: Double the 10% figure. 20% of $347 = $69.40
  • 15%: Add 10% + 5%. 15% of $347 = $34.70 + $17.35 = $52.05
  • 25%: Divide by 4. 25% of $80 = $20
  • 1%: Move decimal two places left. 1% of $3,400 = $34

Common Real-World Percentage Calculations

SituationCalculationExample
Sales discountOriginal × (1 − discount%)$120 × 0.75 = $90 (25% off)
Tax addedPrice × (1 + tax%)$50 × 1.08 = $54 (8% tax)
Tip calculationBill × tip%$85 × 0.20 = $17 tip
Investment return((End − Start) ÷ Start) × 100($12,000 − $10,000) ÷ $10,000 = 20%
Grade score(Correct ÷ Total) × 100(38 ÷ 50) × 100 = 76%