About This Percentage Calculator
Percentages are used everywhere: calculating discounts at the store, understanding interest rates, reading statistics, tracking performance changes, figuring out tips, and more. This free percentage calculator covers the three most common percentage calculations with instant, no-fuss results.
Finding X% of Y
The most common percentage question: “What is 20% of $85?” Enter the percentage and the base number and the answer appears immediately. This is useful for calculating discounts (15% off $120 = $18 off), tips (18% of $47 = $8.46), taxes, commissions, and study scores. The formula is simple: result = (percentage / 100) × value.
Calculating Percentage Change
Percentage change measures how much a value has increased or decreased relative to its starting point. Use it to analyze price changes, salary increases, test score improvements, or any before-and-after comparison. The formula is: ((new − old) / |old|) × 100. A positive result means an increase; negative means a decrease. For example, sales going from $5,000 to $6,250 is a 25% increase.
X is What % of Y
This mode answers questions like “30 is what percent of 150?” — useful for calculating grades (you got 42 out of 50 — that's 84%), market share (your company has 1,200 customers out of a market of 15,000), completion rates, and survey results. The formula is: (X / Y) × 100.
Common Percentage Examples
- 15% tip on a $60 bill = $9.00
- 25% discount on a $80 item = $20 off ($60 final price)
- Score of 37/40 = 92.5%
- Price increase from $200 to $250 = 25% increase
- VAT: 20% of £450 = £90 (total £540)
Frequently Asked Questions
- Is there a quick mental math shortcut for percentages?
- Yes — to find 10%, just move the decimal point one place left. For 5%, halve that. For 20%, double the 10% figure.
- Can I calculate percentage decrease?
- Yes — use the “% Change” tab, enter the higher value as “From” and the lower value as “To”. The result will be a negative percentage.