1. Percentage of a Number (What is X% of Y?)
Calculate a percentage of any number instantly. Try this calculator.
What it does: The "Percentage of a Number" calculator tells you the result of a given percentage of any given number. In other words, it answers questions like “What is 20% of 250?” or “How much is 5% of 1,200?” This is one of the most common percentage calculations – essentially finding a part of a whole.
When to use it: Use this calculator whenever you need to find a portion of a total based on a percentage. Typical use cases include: calculating sales tax or VAT (e.g. 8% of a price), tips at a restaurant (e.g. 15% of the bill), commission on sales, or the amount of an ingredient in a recipe (if expressed as a percentage). It's useful for any scenario where you have a total and a percentage, and you want to know the actual amount that percentage represents.
How to use it: Enter the percentage (X%) and the number (the whole or total, Y) into the calculator. The tool will multiply the number by the percentage (as a fraction of 100) to give you the result. The mathematical formula is simply:
For example, to find 10% of $150, convert 10% to a decimal (0.10) and multiply by 150. This gives 0.10 × 150 = 15, so 10% of $150 is $15. As a real-life example, if a jacket costs $150 and is marked "10% off", the discount amount is $15 and you would pay $135. Our calculator will instantly compute such results, saving you from manual multiplication.
Result = X / 100 × YFor example, to find 10% of $150, convert 10% to a decimal (0.10) and multiply by 150. This gives 0.10 × 150 = 15, so 10% of $150 is $15. As a real-life example, if a jacket costs $150 and is marked "10% off", the discount amount is $15 and you would pay $135. Our calculator will instantly compute such results, saving you from manual multiplication.
2. What Percentage of One Number is Another (X is what % of Y?)
Find what percent one number is of another. Use this calculator.
What it does: This calculator determines what percentage one number is of another number. In plain language, it answers questions like “X is what percent of Y?” or “What percent of total is this part?”. It calculates the ratio of a part to a whole and then converts it into a percentage.
When to use it: Use this when you have two numbers and want to express the first number as a percentage of the second. Common scenarios include finding your score percentage (e.g. you got 45 points out of 60 on a test – what percent is that?), comparing subgroups in data (e.g. 30 out of 200 people prefer option A – that's what percent of the group?), or figuring out percentages in finances (e.g. your monthly rent is $800 out of a $3,200 income – what percent of your income is that?). Essentially, anytime you need to find “what percent” one number is of another, this tool is ideal.
How to use it: Input the part value in the first field and the total (whole) value in the second field. The calculator will divide the part by the whole, then multiply by 100 to give a percentage. The formula is:
For example, if 100 out of 500 equals 20%, this means 100 is 20% of 500 (since 100 ÷ 500 = 0.20, and 0.20 × 100% = 20%). In a practical case, if a survey of 500 people found that 100 people preferred a certain product, that means 20% of the respondents prefer that product. The calculator handles these computations instantly. Just remember that the second number you enter should be the total or whole that the first number is a part of.
Percentage = (Part / Whole) × 100%For example, if 100 out of 500 equals 20%, this means 100 is 20% of 500 (since 100 ÷ 500 = 0.20, and 0.20 × 100% = 20%). In a practical case, if a survey of 500 people found that 100 people preferred a certain product, that means 20% of the respondents prefer that product. The calculator handles these computations instantly. Just remember that the second number you enter should be the total or whole that the first number is a part of.
3. Percentage Change (Increase or Decrease)
Find the % increase or decrease between two numbers. Use the tool here.
What it does: The "Percentage Change" calculator computes the percentage increase or decrease from an initial value to a final value. It tells you by what percent something has grown or shrunk. The result can be positive (percent increase) or negative (percent decrease), and it’s often labeled with a + or – sign or with words “increase” or “decrease”. Essentially, it answers questions like “What is the percent change from A to B?”.
When to use it: Use this for any situation where you’re comparing an old value and a new value and want to express the change as a percentage. Examples include: calculating how much a price has gone up or down (e.g. a stock price rose from $50 to $75 – what is the percent increase?), changes in population or sales figures over time, percentage weight loss or gain, or differences in experiment readings. Businesses use it to report growth rates, and individuals use it to see relative change (for instance, “my electric bill decreased by 15% compared to last month”). If you see phrases like “percentage increase”, “percentage decrease”, or “percent change”, this is the calculator to use.
How to use it: Enter the starting value (initial or "before") and the final value ("after") into the calculator. The tool will calculate the difference, divide by the absolute value of the original value, and multiply by 100%. The formula for percentage change is:
If the resulting percentage is positive, it's an increase; if negative, it's a decrease. For example, going from 50 to 75 is an increase of 25, which relative to the original 50 is +50%. Conversely, dropping from 75 to 50 is a change of -25, which relative to 75 is about -33.3% (a 33.3% decrease).
Percent Change = ((Final − Initial) / |Initial|) × 100%If the resulting percentage is positive, it's an increase; if negative, it's a decrease. For example, going from 50 to 75 is an increase of 25, which relative to the original 50 is +50%. Conversely, dropping from 75 to 50 is a change of -25, which relative to 75 is about -33.3% (a 33.3% decrease).
Example: Suppose last year your rent was £1000 and this year it’s £1100. The increase is £100. Dividing 100 by the original 1000 gives 0.1, and multiplying by 100% yields a 10% increase. If the numbers were reversed (£1100 down to £1000), the change is -£100, divided by 1100 is about -0.0909, times 100% ≈ -9.09%, meaning a 9.09% decrease.
4. Add a Percentage to a Number
Add tax, tips, or markups to any base value. Try the multi step calculator.
What it does: This calculator helps you increase a number by a certain percentage. It answers queries such as “Add 15% to 200” or “200 + 15% = ?”. Essentially, it's used for taking an original value and applying a percentage increase to it, giving a larger result. It’s like a quick way to do “original + (original × percentage)”.
When to use it: Use the "Add a Percentage" tool for scenarios like calculating markups, taxes, or any kind of percentage-based growth on a single value. Examples: adding sales tax to a price (e.g. add 8% VAT to £50), giving a raise or bonus in terms of percentage (e.g. a 5% salary increase on $40,000), or figuring out a tip (e.g. 20% tip on a $45 bill). If you think in terms of “X plus Y%”, this is the calculator you need. It's very handy for shopping (adding tax), dining (tips), or budgeting (price increases).
How to use it: Enter the original number in the first field and the percentage you want to add in the second field. The calculator will compute the increment and add it to the original. The math behind the scenes: to add P%, you can multiply the original number by
(1 + P/100). This factor accounts for the original 100% plus the additional P%.
Example: Adding 20% to 200:
200 × (1 + 0.20) = 200 × 1.20 = 240. The result 240 is 20% higher than 200 (and indeed 200 + 40 = 240, since 40 is 20% of 200). You can also think of it in two steps: first find 20% of 200 (which is 40) and then add it to 200 to get 240. The calculator does both steps in one go.
Another example: 25,000 + 9% =
25,000 × 1.09 = 27,250. This shows how 1.09 includes the original amount (1.00 or 100%) plus 0.09 (9%), yielding the increased total.
5. Subtract a Percentage from a Number
Discounted price? This calculator subtracts percentages. Try the this tool.
What it does: This calculator helps you decrease a number by a certain percentage. It addresses questions like “Subtract 25% from 80” or “80 - 25% = ?”. It’s essentially the opposite of the previous tool: taking an original value and removing a certain percentage of it, giving a smaller result. This is commonly used to find discounted prices or reduced quantities.
When to use it: Use "Subtract a Percentage" for any situation involving a percentage decrease. The classic example is calculating sale prices (e.g. an item is 25% off – what’s the new price?). Other use cases: depreciation of values (like a car value dropping 10% each year), calculating weight loss (e.g. you lost 5% of your body weight), or any “X minus Y%” scenario. If you see terms like “percent off”, “discount”, or “decrease by X%”, this calculator applies.
How to use it: Enter the original number in the first field and the percentage you want to subtract in the second field. The calculator will determine the decrement and subtract it from the original. Mathematically, subtracting P% is achieved by multiplying the original number by
(1 - P/100). The factor (1 - P/100) represents keeping the remaining percentage after removing P%.
Example: To subtract 20% from 200:
200 × (1 - 0.20) = 200 × 0.80 = 160. The result 160 is 20% less than 200 (since 20% of 200 is 40, and 200 - 40 = 160). You effectively paid 80% of the original price in this case.
Another example:
25,000 - 9% = 25,000 × 0.91 = 22,750. Here, 0.91 is the result of 1 - 0.09, meaning you keep 91% of the value after a 9% reduction.
Many find it intuitive to first compute the percentage and then subtract: for example, find 25% of 80 (which is 20), then subtract to get 80 - 20 = 60. The calculator automates both steps.
6. Calculate Total from Part and Percentage
Know the part and %? Find the total. Use the reverse calculator.
What it does: This calculator works in reverse of the first two scenarios – it finds the original total given a part and the percentage that part represents. In other words, it answers questions like “Y is X% of what number?” or “If 30 is 15% of the total, what is the total?”. It’s sometimes called a reverse percentage calculator or used to find the whole given the part and percent.
When to use it: Use this when you know a portion of something and how large that portion is in percentage terms, and you need to find the full amount. Real-life situations include:
• Finding the total budget if you know a department’s spending and its percentage (e.g. “$50k is 20% of our budget – what’s the total?”)
• Figuring out full test marks if you know your score and percentage (e.g. “I got 45 which was 75% – what was the total?”)
• Population estimates (e.g. “120 people represent 15% of the town – what’s the total population?”)
How to use it: Enter the known part value in the first field and the percentage it represents in the second field. The calculator will output the total (whole) value. The formula used is:
This comes from rearranging the basic percentage formula:
Whole = (Part × 100) / PercentageThis comes from rearranging the basic percentage formula:
Part = (Percentage / 100) × Whole
Example: If 30 is 15% of something, the calculation would be:
Whole = 30 × 100 / 15 = 200.
So, 30 is 15% of 200.
Another example: if 70% of a number is 210, the original number is
210 ÷ 0.70 = 300.
Similarly, if $25 is 5% of your income, then your income is
25 × 100 / 5 = 500.
These quick reverse calculations are useful in shopping, finance, exams, and more.
7. Number Before Percentage Decrease
Got the result after a drop? Find the original. Check it here.
What it does: The "Number Before Percentage Decrease" calculator finds the original value before a known percentage decrease occurred, given the final value after the decrease. It answers questions like “We ended up at Z after a P% decrease – what was the starting value?”. This is a specific reverse percentage scenario, often used to work out the original value before a discount, loss, or reduction.
When to use it: Use this in situations like:
• Calculating the original price of an item before a sale discount
• Working out the initial stock value before a drop in price
• Determining the starting quantity or population before shrinkage
This calculator is perfect when you know something dropped by a certain percent and you want to know where it started from. Common in retail, accounting, and statistical decline tracking.
How to use it: Enter the final value (after decrease) in the first field, and the percentage decrease in the second. The calculator will then return the original value.
The formula used is:
Original = Final / (1 - P/100)
Since the final is the remainder after removing a percentage, dividing by that remaining fraction reveals the starting value.
Example:
If the final number is 100 after a 50% decrease:
Another example: a toy is priced at $210 after a 20% discount.
If a town’s population fell by 5% to 95,000:
These examples show how the calculator finds the base value before a reduction took place.
Original = 100 / (1 - 0.50) = 100 / 0.50 = 200Another example: a toy is priced at $210 after a 20% discount.
Original = 210 / (1 - 0.20) = 210 / 0.80 = 262.50If a town’s population fell by 5% to 95,000:
Original = 95,000 / 0.95 = 100,000These examples show how the calculator finds the base value before a reduction took place.
8. Number Before Percentage Increase
Know the final price after markup? Find the base. Try this calculator.
What it does: This calculator finds the original value before a known percentage increase, given the final value after the increase. It answers questions like “We have Z after a P% increase – what was the starting value?”. It’s useful for reversing markup, tax, growth, or inflation calculations to find the baseline amount.
When to use it: Use this for scenarios such as:
• Calculating the price before a markup or tax was added
• Reversing population growth to find last year’s number
• Undoing a salary or investment increase to reveal the original value
Common examples include shopping, budgeting, salary planning, and finance reports. It’s especially helpful if you're trying to get the “before” picture in any growth-related situation.
How to use it: Enter the final value (after increase) in the first field, and the percentage increase in the second. The calculator will compute the original value.
The formula used is:
Original = Final / (1 + P/100)
Because the final value includes both the original and the added percentage, dividing by that factor retrieves the base value.
Example:
If the final number is 450 after a 50% increase:
Another case: an item costs $120 after a 20% markup.
One more: a town’s population is 105,000 after a 5% growth.
In each case, the calculator gives you the starting value before the percentage increase occurred.
Original = 450 / 1.50 = 300Another case: an item costs $120 after a 20% markup.
Original = 120 / 1.20 = 100One more: a town’s population is 105,000 after a 5% growth.
Original = 105,000 / 1.05 = 100,000In each case, the calculator gives you the starting value before the percentage increase occurred.
Conclusion: Leverage Percent Calculators for Easy, Accurate Math
With these eight calculators, anyone can handle percentage calculations quickly and correctly – no advanced math skills or special functions needed. From figuring out percentages of numbers to reversing out original values from percentage changes, our tools cover all common scenarios in personal finance, shopping, academics, and beyond.
Using these calculators not only saves time but also helps you understand the math behind the results. Each explanation above included formulas and examples to illustrate how the calculation works (e.g., showing that adding 15% means multiplying by 1.15, or how a percent change formula is applied). This knowledge can be empowering – knowing how percentages work gives you the power to analyze data in everyday life.
Real-life applications include:
- Shopping Discounts and Tax: Instantly compute sale prices or add taxes (e.g. 30% off or adding 7% tax) without fiddling with a regular calculator.
- Personal Finance: Calculate raises, interest rates, loan payment changes, or what portion of your budget something represents.
- Health and Fitness: Track weight loss/gain percentages or nutritional values (like what percent of daily intake a food provides).
- Education and Work: Find grade percentages, statistics (what percent of survey respondents chose X), or growth metrics for business.
Each calculator is optimized for mobile use, ensuring a smooth experience on smartphones or tablets – perfect for quick calculations on the spot.
By including relevant keywords and clear headings in this guide, we've made it easy for search engines to direct you here when you ask things like "how to calculate a percentage" or "percentage increase calculator". Bookmark this page as your go-to reference for percentage calculations.
With a solid grasp of these concepts and our calculators at your fingertips, percentage problems will never perplex you again – and you'll make more informed decisions based on precise data. Happy calculating!