Percentage Calculator Online
Six calculators in one — percentage of a number, percentage change, reverse percentage, and more. Instant results, no page reloads.
What Is a Percentage — and Why Does the Formula Matter?
A percentage is a ratio expressed as a fraction of 100. When you say 25%, you mean 25 out of every 100 — a universal scale that makes unlike quantities directly comparable. The core percentage formula is simple: (Part ÷ Whole) × 100. Every other percentage calculation — change, difference, markup, discount — is a variation of that same relationship.
Where people get tripped up is not the formula itself but knowing which formula applies. Calculating what percentage one number is of another is not the same as calculating a percentage change between two numbers, and neither is the same as finding the original value before a percentage was added or removed. The calculator above handles all six scenarios without switching tabs in a spreadsheet or reaching for a pen.
All Six Percentage Formulas — Quick Reference
| Calculation Type | What You Know | Formula | Example Answer |
|---|---|---|---|
| % of a Number | % and total | (% ÷ 100) × Number | 25% of 200 = 50 |
| % Change | Original and new value | ((New − Old) ÷ Old) × 100 | 80 → 100 = +25% |
| X as % of Y | Part and whole | (X ÷ Y) × 100 | 30 of 300 = 10% |
| Add/Remove % | Number and % | Number × (1 ± %/100) | 500 + 15% = 575 |
| Reverse % | Final value and % | Final ÷ (1 + %/100) | 115 after +15% → 100 |
| % Difference | Two values, no direction | |A−B| ÷ ((A+B)/2) × 100 | 40 vs 60 = 40% |
How to Calculate Percentages — Step by Step
Exam Scores & Marks
Got 72 out of 90? Use X is What % of Y: (72 ÷ 90) × 100 = 80%. Works for CGPA conversion and aggregate percentage too.
Discounts & VAT
Applying a 20% discount? Use Remove %. Adding 5% VAT? Use Add %. Reverse % finds the pre-tax price from the final bill.
Salary & Raise
Going from AED 8,000 to AED 9,500? Use % Change: ((9500 − 8000) ÷ 8000) × 100 = 18.75% increase.
Stock & Investment
Track percentage gain or loss on any asset. Use % Change for return on investment, or % Difference to compare two portfolio values neutrally.
Percentage Formulas in Detail
Whole = the total or reference value
Result = how many per hundred the Part represents
Negative result = percentage decrease
Note: always divide by the original value, never the new one
Frequently Asked Questions
How do I calculate % of a total?
Divide the part by the total, then multiply by 100. If 45 students passed out of 180, the percentage is (45 ÷ 180) × 100 = 25%. Use the “X is What % of Y” tab in the calculator above to get the result instantly without manual arithmetic.
How do I calculate to get a percentage?
The universal method: divide the value you want to express as a percentage by the reference total, then multiply by 100. For exam marks, the reference total is the maximum marks. For discounts, it is the original price. For growth, it is the starting value. The formula is always (Part ÷ Whole) × 100.
What is 30% out of 300?
30% of 300 equals 90. Using the formula: (30 ÷ 100) × 300 = 90. You can verify this instantly using the “% of a Number” tab — enter 30 in the percentage field and 300 in the number field.
What is 20% out of 100?
20% of 100 equals 20. Since the total is 100, the percentage and the resulting value are the same number — this is the special case where the whole equals 100. For any other total, use (20 ÷ 100) × total.
What is the difference between percentage change and percentage difference?
Percentage change measures how much a value moved from a defined starting point — it has a direction (increase or decrease) and always divides by the original value. Percentage difference compares two values without a defined starting point — it divides by their average and is always expressed as a positive number. Use change when tracking progress over time; use difference when comparing two independent values.
How do I find the original price before a discount?
Use the Reverse % calculator. If a product costs AED 850 after a 15% discount, enter 850 as the final value and −15 as the percentage. The formula is: Original = Final ÷ (1 − 0.15) = 850 ÷ 0.85 = AED 1,000. This is also how you back-calculate pre-VAT prices from a VAT-inclusive total.
How do I calculate percentage of marks?
Divide the total marks obtained by the maximum marks, then multiply by 100. If you scored 430 out of 500, your percentage is (430 ÷ 500) × 100 = 86%. For aggregate percentage across multiple subjects, sum all marks obtained and divide by the sum of all maximum marks before multiplying by 100.
Does this percentage calculator work for UAE VAT (5%)?
Yes. To add 5% VAT to any price, use the “Add / Remove %” tab — enter your pre-tax amount and 5 as the percentage. To find the pre-tax price from a VAT-inclusive total, use “Reverse %” with 5 as the percentage. Both calculations are instant and work for any VAT rate, not just the UAE standard rate.