To find X% of Y, multiply Y by X and divide by 100. Formula: (Y × X) ÷ 100. Example: 15% of 200 = (200 × 15) ÷ 100 = 30. Our calculator does this automatically the moment you type both values.

Percentage Calculator

Q: How do I calculate a percentage?

Divide the part by the whole, then multiply by 100. Formula: Percentage = (Part ÷ Whole) × 100. For example, 20 out of 80 = (20 ÷ 80) × 100 = 25%.

Q: How to calculate percentage of marks?

Add up all the marks you scored, divide by the total possible marks, then multiply by 100. Example: 425 obtained ÷ 500 total × 100 = 85%. This is the standard method used for school and university exam results.

Q: How do I calculate percentage increase or decrease?

Percentage change = ((New value − Old value) ÷ Old value) × 100. A positive result is an increase, a negative result is a decrease. Example: going from 80 to 100 is a ((100 − 80) ÷ 80) × 100 = 25% increase.

Q: What is a reverse percentage calculation?

A reverse percentage finds the original value before a percentage was applied. Formula: Original = Final ÷ (1 + rate) for an increase, or Final ÷ (1 − rate) for a decrease. Example: if a discounted price is $80 after 20% off, original = 80 ÷ 0.8 = $100.

Q: How do I convert a decimal to a percentage?

Multiply the decimal by 100 and add a percent sign. Example: 0.75 → 75%. To convert a percentage back to a decimal, divide by 100: 45% → 0.45.

Q: What is the difference between percentage and percentile?

Percentage is a portion of 100 (your score out of the total). Percentile is your rank compared to others. Scoring 80% means you got 80 out of 100 marks. Being in the 80th percentile means you scored higher than 80% of test-takers.

Q: How do I find what percent one number is of another?

Divide the smaller number by the larger number, then multiply by 100. Example: what percent is 15 of 60? (15 ÷ 60) × 100 = 25%. Enter both values in our calculator for an instant answer.

Q: Is this percentage calculator free?

Yes — 100% free, no signup, no ads on the tool, works on any device. Enter your value and percentage to get instant results with a live breakdown chart.

Q: Can I use this for discount and tax calculations?

Yes. Enter the original price as the base value and the discount or tax rate as the percentage. The result shows the discount/tax amount and the remainder shows the final price.

Free percentage calculator online — find what X% of Y is, percentage increase or decrease, and reverse percentages instantly. No signup, works on any device.

Enter a value and percentage to see the result here.

What Is a Percentage?

A percentage is a number expressed as a fraction of 100. The word literally comes from Latin — per centum, "out of a hundred". A score of 85% means 85 out of every 100. It's the most universal way to express proportions, comparisons, discounts, growth rates, and test results because it works across any scale.

This free percentage calculator online handles the most common calculations — finding what X% of Y is, calculating percentage increase or decrease, working out what percent one number is of another, and reverse percentages. No manual math, no formula hunting.

How to Calculate Percentage — The Core Formulas

There are four percentage calculations you'll actually use in real life. Here's each one with the formula and a worked example:

What You Want to Find	Formula	Example
X% of Y	(Y × X) ÷ 100	20% of 150 = (150 × 20) ÷ 100 = 30
What % is A of B	(A ÷ B) × 100	15 of 60 = (15 ÷ 60) × 100 = 25%
Percentage increase	((New − Old) ÷ Old) × 100	80 → 100 = ((100 − 80) ÷ 80) × 100 = 25% increase
Percentage decrease	((Old − New) ÷ Old) × 100	100 → 80 = ((100 − 80) ÷ 100) × 100 = 20% decrease

Notice something important: 80 → 100 is a 25% increase, but 100 → 80 is only a 20% decrease. Percentage changes are always relative to the starting value.

How to Use This Percentage Calculator

Enter your base value in the first field (the total, the original number, or the "whole").
Enter the percentage you want to apply in the second field.
Click Calculate — or watch the result panel update automatically.

The result panel shows the calculated amount, the remainder (base value minus the result), and a live breakdown chart so you can see the proportion at a glance.

What Is X% of Y? — Quick Reference Chart

The most common everyday percentage question. Here are the most searched X% of Y calculations pre-worked:

Calculation	Result	Common Use
5% of 100	5	Sales tax
10% of 100	10	Standard tip
15% of 100	15	Restaurant tip
20% of 100	20	Discount, tip
25% of 200	50	Quarter off sale
30% of 500	150	Clearance discount
50% of 80	40	Half-off deal
75% of 200	150	Progress tracking
90% of 1000	900	Exam target

How to Calculate Percentage of Marks

One of the most searched percentage calculations, especially for school and university students. The formula is straightforward:

Percentage of marks = (Marks obtained ÷ Total marks) × 100

Worked examples:

Scored 450 out of 500 → (450 ÷ 500) × 100 = 90%
Scored 68 out of 80 → (68 ÷ 80) × 100 = 85%
Scored 340 out of 400 → (340 ÷ 400) × 100 = 85%

For calculating multi-subject percentages, add all the marks obtained across every subject, divide by the sum of all total marks, then multiply by 100. If you're working with GPA instead of marks, use our GPA to percentage calculator for direct conversion.

Percentage Increase From One Number to Another

Used in salaries, prices, populations, and any "what's the growth rate" question. Formula:

Percentage increase = ((New − Old) ÷ Old) × 100

Examples:

Salary rose from $50,000 to $55,000 → ((55,000 − 50,000) ÷ 50,000) × 100 = 10% increase
Price went from $80 to $92 → ((92 − 80) ÷ 80) × 100 = 15% increase
Followers grew from 1,200 to 1,500 → ((1,500 − 1,200) ÷ 1,200) × 100 = 25% increase

Percentage Decrease Calculator

The mirror of percentage increase — used for sales, weight loss, expense cuts, and stock drops. Formula:

Percentage decrease = ((Old − New) ÷ Old) × 100

Examples:

Weight dropped from 90 kg to 81 kg → ((90 − 81) ÷ 90) × 100 = 10% decrease
Price fell from $200 to $150 → ((200 − 150) ÷ 200) × 100 = 25% decrease
Traffic went from 10,000 to 7,500 visits → 25% decrease

Reverse Percentage Calculator (Finding the Original Value)

The trickiest percentage question — and the most misunderstood. Reverse percentage works out the original value when you only know the final value and the percentage that was applied.

Formulas:

After an increase: Original = Final ÷ (1 + rate ÷ 100)
After a decrease: Original = Final ÷ (1 − rate ÷ 100)

Worked examples:

A shirt costs $80 after a 20% discount. Original price = 80 ÷ (1 − 0.20) = 80 ÷ 0.80 = $100
Bill total is $110 with 10% VAT. Pre-tax = 110 ÷ 1.10 = $100
Salary is $63,000 after a 5% raise. Old salary = 63,000 ÷ 1.05 = $60,000

Common mistake: don't just subtract 20% from the discounted price to get the original. You have to divide, not subtract.

Decimal to Percentage Converter

Converting between decimals and percentages is simple once you learn the trick:

Decimal to percentage: multiply by 100 (0.45 → 45%)
Percentage to decimal: divide by 100 (75% → 0.75)
Fraction to percentage: divide numerator by denominator, then × 100 (3/4 → 0.75 → 75%)

Quick reference chart:

Decimal	Percentage	Fraction
0.01	1%	1/100
0.05	5%	1/20
0.10	10%	1/10
0.25	25%	1/4
0.33	33.33%	1/3
0.50	50%	1/2
0.66	66.67%	2/3
0.75	75%	3/4
0.80	80%	4/5
1.00	100%	1/1

Percentage vs Percentile — What's the Difference?

These get mixed up constantly, especially around test scores. They mean very different things:

Concept	What It Measures	Example
Percentage	Your score as a fraction of 100	85% = you got 85 out of 100 marks
Percentile	Your rank relative to others	85th percentile = you scored higher than 85% of test-takers

Someone can score 60% on a hard exam and still be in the 95th percentile if most people scored lower. Standardized tests like the GRE, SAT, and GMAT report percentiles because they compare you to the test-taker pool, not to a fixed 100-point scale.

Real-World Uses of Percentage Calculations

Shopping — discounts, "buy one get one 50% off", sales tax, VAT
Finance — interest rates, loan APR, investment returns, inflation
Salary & work — raises, bonuses, tax deductions, tips
School & exams — marks percentages, grade thresholds, grade curves
Health & fitness — body fat %, weight change %, calorie targets
Business — profit margin, growth rate, conversion rate, market share
Analytics — bounce rate, CTR, engagement rate
Cooking & recipes — scaling ingredients, baking ratios (baker's percentage)

Common Percentage Calculation Mistakes to Avoid

Adding then subtracting the same percentage doesn't return the original. $100 → +10% = $110 → −10% = $99, not $100.
Percentage increase and decrease aren't symmetric. Going from 100 to 150 is a 50% increase, but 150 to 100 is only a 33.33% decrease.
Don't confuse percentage with percentage points. Interest rising from 5% to 7% is a 2 percentage point increase, but a 40% relative increase.
Reverse percentages need division, not subtraction. $80 after 20% off is not $80 + $20 = $100; it's $80 ÷ 0.80 = $100.

Why Use This Free Percentage Calculator

✅ 100% free — no signup, no ads on the tool
✅ Instant, live results as you type
✅ Handles X% of Y, percentage increase, decrease, and reverse percentage
✅ Visual breakdown — see result vs remainder proportion at a glance
✅ Works for discounts, tax, tips, marks, growth rates — anything percentage-based
✅ Mobile-friendly — phone, tablet, laptop, desktop

Frequently Asked Questions

How do I calculate a percentage?

What is X% of Y?

How to calculate percentage of marks?

How do I calculate percentage increase or decrease?

What is a reverse percentage calculation?

How do I convert a decimal to a percentage?

What is the difference between percentage and percentile?

How do I find what percent one number is of another?

Is this percentage calculator free?

Can I use this for discount and tax calculations?

Final Thoughts

Percentages are one of the most useful pieces of math you'll ever learn — whether you're checking a discount, tracking your exam scores, or calculating a raise. Bookmark this percentage calculator for the next time you need any of these calculations, and use the reference tables above when you don't have the calculator open.

For related calculations, try our GPA to percentage converter if you're working with academic grades, or the GPA calculator to compute GPA from credit hours and letter grades.