8 percentage calculators in one — from basic percentage of a number to discount, markup, reverse percentage, percentage error, and more. Every result comes with a step-by-step solution.
Result = (Percentage ÷ 100) × Number
Example: What is 35% of 200? → (35 ÷ 100) × 200 = 70
Percentage = (X ÷ Y) × 100
Example: 45 is what % of 180? → (45 ÷ 180) × 100 = 25%
The part — the number you want to express as a percentage
The whole — the number you are comparing against
Discount Amount = Price × (Discount % ÷ 100) Final Price = Original Price − Discount Amount
The original price before discount
The percentage being taken off
Markup % = ((Sell − Cost) ÷ Cost) × 100 Gross Margin % = ((Sell − Cost) ÷ Sell) × 100
Markup is based on cost · Margin is based on selling price
How much you paid for the item (your cost)
How much you are charging the customer
% Difference = |A − B| ÷ ((A + B) ÷ 2) × 100
Use this when neither value is the "original" — both are equally valid
The first value
The second value
After Increase → Original = Final ÷ (1 + % ÷ 100) After Decrease → Original = Final ÷ (1 − % ÷ 100)
Example: $130 after a 30% increase → 130 ÷ 1.30 = $100
The value you have now — after an increase or decrease was applied
The percentage that was added or subtracted
% Error = (|Estimated − Actual| ÷ Actual) × 100
Measures accuracy of an estimate, prediction, or measurement
Your estimate, guess, or measured result
The correct or accepted value
Result
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📐 Step-by-Step Solution
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📋 Percentage Formula Reference Table
All 8 percentage formulas at a glance — bookmark this page for quick reference.
Calculation Type
Formula
Example
Answer
% of a Number
(P ÷ 100) × N
15% of 300
45
Percentage Change
((New − Old) ÷ Old) × 100
50 → 75
+50%
X is % of Y
(X ÷ Y) × 100
30 of 120
25%
Discount
Price × (D% ÷ 100)
20% off $80
$16 off → $64
Markup %
((Sell − Cost) ÷ Cost) × 100
Cost $40, Sell $60
50% markup
Gross Margin %
((Sell − Cost) ÷ Sell) × 100
Cost $40, Sell $60
33.3% margin
% Difference
|A−B| ÷ ((A+B)÷2) × 100
80 vs 100
22.2%
Reverse % (increase)
Final ÷ (1 + P÷100)
$130 after +30%
$100
Reverse % (decrease)
Final ÷ (1 − P÷100)
$70 after −30%
$100
% Error
|Est − Actual| ÷ Actual × 100
Est 9.5, Actual 10
5%
🌍 Real-World Uses of Percentage Calculators
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Shopping & Sales
Calculate discount savings, compare sale prices, find the actual price after coupons or cashback.
Set product prices with the right markup, calculate gross margin, and track revenue changes month-over-month.
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Education & Grades
Find your exam score percentage, grade point averages, or what score you need to pass.
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Health & Nutrition
Calculate daily calorie percentages, macronutrient ratios, body fat percentage change, and BMI shifts.
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Real Estate & Tax
Calculate property value changes, rental yield percentages, tax rates, and stamp duty as a percentage of price.
Understanding Percentages — A Complete Guide
The word percentage comes from the Latin "per centum" — meaning "per hundred." A percentage is simply a way of expressing a number as a fraction of 100. When you say 75%, you mean 75 out of every 100, or equivalently, the fraction 75/100 = 0.75.
Percentage vs Percentage Points
These are often confused. If an interest rate rises from 4% to 6%, it has increased by 2 percentage points, but it has increased by 50% (since 2 is 50% of 4). In statistics, economics, and finance, using the wrong term can change the entire meaning of a statement.
Markup vs Margin — A Common Confusion
Many business owners confuse markup and margin. Markup is the percentage added to the cost to get the selling price (calculated on cost). Margin (gross profit margin) is the profit as a percentage of the selling price. A 50% markup does not equal a 50% margin — it equals a 33.3% margin. Getting this right is critical for correct pricing decisions.
Percentage Change vs Percentage Difference
Percentage change implies a direction — one value is "original" and one is "new." It tells you how much something grew or shrank. Percentage difference is symmetric — it compares two equal-standing values using their average as the denominator. Use difference when you are comparing two measurements, prices, or statistics without a clear "before" and "after."
The Reverse Percentage Trick
Reverse percentage is one of the most overlooked yet useful calculations in everyday life. If a sale price is £84 after a 30% discount, most people try to calculate 30% of £84 and add it back — which is wrong. The correct approach: £84 ÷ 0.70 = £120 (the original price). This calculator handles that automatically.
Frequently Asked Questions
Multiply the number by the percentage, then divide by 100. Formula: (P ÷ 100) × N. Example: 20% of 150 = (20 ÷ 100) × 150 = 30.
Formula: ((New − Old) ÷ Old) × 100. A positive result is an increase; negative is a decrease. Example: from 80 to 100 = ((100 − 80) ÷ 80) × 100 = 25% increase.
Markup = ((Sell − Cost) ÷ Cost) × 100 — based on cost. Margin = ((Sell − Cost) ÷ Sell) × 100 — based on selling price. A 50% markup = 33.3% margin. They are not interchangeable.
Use reverse percentage: Original = Sale Price ÷ (1 − Discount% ÷ 100). Example: £84 after 30% off → 84 ÷ 0.70 = £120. Never add the discount % to the sale price — that gives the wrong answer.
Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100. Use it when comparing two values where neither is the "original" — like comparing two competitors' prices, two exam scores, or two measurements. Use percentage change when one value clearly comes before the other.
Formula: (|Estimated − Actual| ÷ Actual) × 100. It shows how accurate an estimate or measurement is. A 0% error = perfect accuracy. Lower is better. Used in science, engineering, and forecasting.
If something rises from 4% to 6%, it increased by 2 percentage points but by 50% in relative terms. Percentage points measure absolute change in a percentage value. Confusing these two is a very common error in media and business reporting.
To add VAT: Price × (1 + VAT% ÷ 100). Example: £100 + 20% VAT = £120. To find the pre-VAT price from a VAT-inclusive price: Inclusive Price ÷ (1 + VAT% ÷ 100). Example: £120 ÷ 1.20 = £100. Use the Reverse % calculator above for this.