Percentage Calculator
X% of Y, share as a percent, and percent change-with formulas, examples, and FAQ in your browser.
Everyday Examples
🛒 Shopping sale
Jacket €80, 20% off → save €16, pay €64.
🧾 VAT / sales tax
€100 + 23% VAT → €23 tax, total €123.
📈 Salary raise
€3,000/mo + 5% → +€150, new €3,150.
🏦 Bank interest
€10,000 at 4%/yr → €400 interest (simple).
☕ Price increase
€2.50 → €2.80 → ≈12% vs old price.
📊 Exam score
42 / 56 right → 75%.
How to Calculate Percentages
Quick context, then worked tables aligned with the calculator tabs.
When should you use this?
🧾 Checkout & invoices
Find a discount or tax slice of a total.
💼 Pay & grades
Turn part vs whole into a percent.
📈 Trends
Old vs new price or KPI - change vs the starting value.
Common mistakes
⚠️ Points vs change
Mixing percentage points (e.g. 20% → 25% = 5 points) with relative % change.
🧮 Discount & tax
Wrong order of discount and tax.
🔢 Wrong whole
In X vs Y, name your denominator before calculating.
What is X% of Y? (parts of a whole)
Discounts, tips, tax: you know the rate - multiply total × (percent ÷ 100).
| Question | Calculation | Answer | Real-world context |
|---|---|---|---|
| What is 10% of 50? | 50 × 0.10 | 5 | Ten percent deposit on a 50 unit bill |
| What is 25% of 200? | 200 × 0.25 | 50 | Quarter of a 200 unit project budget |
| What is 8% of 1200? | 1200 × 0.08 | 96 | Rough VAT-style chunk on a 1200 total |
| What is 15% of 84? | 84 × 0.15 | 12.6 | Restaurant tip line on an 84 check |
| What is 3% of 9500? | 9500 × 0.03 | 285 | Small percent fee on a large transfer |
X is what % of Y? (share or completion)
Part ÷ whole × 100 - scores, progress, share of a total.
| Question | Calculation | Answer | Real-world context |
|---|---|---|---|
| 30 is what % of 150? | (30 ÷ 150) × 100 | 20% | One line item versus whole invoice |
| 7 is what % of 28? | (7 ÷ 28) × 100 | 25% | Weekly workouts completed of a 28-day plan |
| 45 is what % of 90? | (45 ÷ 90) × 100 | 50% | Half the questions correct on a quiz |
| 120 is what % of 400? | (120 ÷ 400) × 100 | 30% | Conversion rate from 400 visitors |
| 18 is what % of 144? | (18 ÷ 144) × 100 | 12.5% | Slice of a 144 hour month on one task |
Percentage change between two values
(new - old) ÷ |old| × 100 - always vs the starting value.
| Question | Calculation | Answer | Real-world context |
|---|---|---|---|
| From 80 to 100 | ((100 - 80) ÷ 80) × 100 | +25% | Revenue lift from a campaign baseline |
| From 200 to 150 | ((150 - 200) ÷ 200) × 100 | -25% | Stock pullback from a recent peak |
| From 40 to 40 | ((40 - 40) ÷ 40) × 100 | 0% | Flat month-over-month metric |
| From 50 to 65 | ((65 - 50) ÷ 50) × 100 | +30% | Support tickets resolved vs prior sprint |
| From 250 to 235 | ((235 - 250) ÷ 250) × 100 | -6% | Utility bill seasonally lower |
Key Percentage Terms
Percentage increase
The relative growth from an original amount expressed in hundredths of that starting value. If sales climb from €1,000 to €1,200, the increase is 20% because the €200 gain is one-fifth of the baseline you measured against.
Profit margin
Profit as a share of revenue, not of cost. A 30% margin means thirty cents of each revenue euro remains after direct expenses. Do not confuse it with markup, which divides by cost instead of price.
Reverse percentage
Working backward from a post-change value to the original whole. If €123 includes 23% tax, the net portion is not 77% of 123 unless the policy says so - define whether the rate applies to net or gross before you invert the operation.
Basis point (finance)
One hundredth of a percentage point. Analysts say 25 bps instead of 0.25 percentage points when discussing bond yields or central bank moves so the increment stays unambiguous on noisy trading floors.
Frequently Asked Questions
Common questions about the percentage calculator.