Math
Percentage Calculator
Calculate increases, discounts and percentage differences.
20% · 250
50
- Formula
- (20 × 250) / 100
How it works
Percentage is a ratio expressed out of 100. The symbol % means "per hundred".
Basic formulas:
Part = (% × Total) / 100 Increase = Value × (1 + % / 100) Discount = Value × (1 − % / 100) Change A→B = ((B − A) / A) × 100
Practical examples
20% of $250
(20 × 250) / 100 = $50.
$120 with 15% discount
120 × (1 − 0.15) = $102. You save $18.
From 80 to 100
((100 − 80) / 80) × 100 = +25%.
Frequently asked questions
How do I compute percentages in my head?
10% = divide by 10; 1% = divide by 100. Combine these blocks for any target value.
Does +50% then −50% return the original?
No. 100 → +50% = 150 → −50% = 75. Discount applies to the already-changed value.
What are 'percentage points'?
The absolute difference between two percentages. 10% → 15% is +5 points (or +50% relative).