Percentage Calculator
Find any percentage instantly — calculate X% of a number, find percentage change, or see what percent X is of Y.
💡 Common Examples
- 📦 10% off $49.99 → $4.99 discount → Pay $44.99
- 💰 15% tip on $60 → $9.00 tip → Total $69
- 📈 Score 80 → 95 → +18.75% improvement
- 🎯 30 out of 120 → 25%
- 🛒 HST (13%) on $100 → $13 tax → Total $113
Percentage Formulas
| Problem | Formula |
|---|---|
| X% of Y | Y × (X ÷ 100) |
| A is what % of B? | (A ÷ B) × 100 |
| % change from A to B | ((B − A) ÷ A) × 100 |
| Add X% to a price | Price × (1 + X ÷ 100) |
| Remove X% from price | Price × (1 − X ÷ 100) |
To reverse a tax (e.g. extract 5% GST): divide total by 1.05 to get the pre-tax price.
Percentage Calculator FAQ
About This Calculator
This percentage calculator combines three tools in one page because percentage problems come in three forms: finding what X% of a number is, finding what percentage one number is of another, and finding how much something has changed as a percentage. Each tab is optimized for one of these use cases, with a step-by-step breakdown of the calculation so you can verify the math or adapt it to slightly different situations.
Percentage calculations come up constantly in everyday Canadian life — calculating GST or HST on a purchase, figuring out a tip at a restaurant, comparing two prices, tracking investment returns, or converting a test score to a grade. The "X% of Y" tab handles discounts, taxes, and tips. The "% Change" tab handles salary increases, price changes, and performance comparisons. The "X is what % of Y" tab handles grade calculations, ratios, and budget allocations.
One common point of confusion: percentage increase and percentage decrease are not symmetric. A 50% increase followed by a 50% decrease does not return you to the original number — you end up with 75% of what you started with. This is because each percentage is calculated on a different base. The Percentage Change tab always makes clear what the base is, so you can catch these asymmetries before they create surprises.