Percentage Calculator – 3-Way Quick Math Tool

Calculate percentage of a number, what percent one number is of another, and percentage increase or decrease instantly.

1. What is X% of Y?

Percentage (%)

Of Value

Result

37.5

2. X is what percent of Y?

Value (Part)

Total (Whole)

Result

25.00%

3. Percentage Increase / Decrease

From Value

To Value

Result

+50.00% (Increase)

Common Percentage Formulas Explained

Percentage of a Number: (Percentage / 100) × Value. For example, 15% of $250 is 0.15 × 250 = $37.50.
What Percent One Number is of Another: (Part / Total) × 100%. Useful for calculating test grades, sales commissions, and progress milestones.
Percentage Change (Increase or Decrease): ((New Value - Old Value) / |Old Value|) × 100%. Ideal for financial market price changes, salary raises, and retail discounts.

How do I calculate a discount?

Subtract the discount percentage from 100% and multiply by the retail price. For instance, a 20% discount on $80 is 0.80 × 80 = $64.

Can percentage change exceed 100%?

Yes. If an investment doubles from $50 to $100, the percentage increase is 100%. If it triples to $150, the increase is 200%.