Free Online Percentage Calculator — Step-by-Step Explanations

Percentage Calculator — Calculate Increase, Decrease & Proportions

What it does: Calculates percentage values for three common tasks:

• Increase: add a percentage to a base value (e.g., apply 15% tax to \(100).</li><li>Decrease: subtract a percentage from a base value (e.g., apply 20% discount to \)50).
• Proportions: find what percentage one number is of another (e.g., 25 of 200 = 12.5%).

How to use (steps):

1. Choose operation: Increase, Decrease, or Proportion.
2. Enter the base value and the percentage (for Increase/Decrease) or enter part and whole (for Proportion).
3. Press calculate to get the result and a brief explanation.

Formulas:

• Increase: result = base × (1 + percent/100)
• Decrease: result = base × (1 − percent/100)
• Proportion: percent = (part ÷ whole) × 100

Examples:

• Increase: 100 with 15% → 100 × 1.15 = 115
• Decrease: 50 with 20% → 50 × 0.80 = 40
• Proportion: 25 of 200 → (25 ÷ 200) × 100 = 12.5%

Tips:

• For reverse problems (find percent given original and new value), use percent = ((new − original) ÷ original) × 100.
• Convert percentages like 150% to decimals by dividing by 100 (1.5) before multiplying.
• Use parentheses when chaining operations to avoid order-of-operations errors.