Percentage Calculator
Calculate percentages instantly. Find X% of Y, what percent X is of Y, percentage change, and increase or decrease by a percentage. Choose a mode, enter your numbers, and see live results. Free, private, and runs entirely in your browser.
Choose a Calculation
Pick a mode and enter your numbersResult = (X ÷ 100) × YResult = (X ÷ Y) × 100Result = ((New − Old) ÷ |Old|) × 100Result = X × (1 + Y ÷ 100)Result = X × (1 − Y ÷ 100)Result
Updates live as you typeQuick Reference
What is X% of Y?
Multiply Y by X, then divide by 100.
X is what % of Y?
Divide X by Y, then multiply by 100.
% Change
((New − Old) ÷ Old) × 100.
What does this percentage calculator do?
This free online percentage calculator handles the five most common percentage problems people need to solve. Instead of remembering formulas or doing mental math, you pick the calculation you want and the answer updates live as you type. No "calculate" button, no page reloads, no waiting.
The five modes cover everything from basic percentage-of-a-number calculations to percentage change and increase/decrease problems. Whether you're working out a discount, checking a test score, calculating a price increase, or comparing two values, there's a mode for it.
Like every tool on Textify.tools, everything runs in your browser. Your numbers never leave your device — there's no server, no logging, and no data stored anywhere.
How to use the percentage calculator
- Pick a mode: Choose from the five buttons at the top: "X% of Y", "X is what % of Y", "% Change", "Increase by %", or "Decrease by %".
- Enter your numbers: Fill in the input fields that appear. The labels tell you exactly what each field expects.
- Use quick buttons (optional): In the "X% of Y" mode, tap a preset percentage (5%, 10%, 15%, etc.) to fill it in instantly.
- Read the result: The large number in the result panel updates live as you type. The label below it shows what the number means.
- Copy if needed: Click "Copy Result" to copy the answer and its context to your clipboard.
That's it. No signup, no email, no waiting.
Why use this percentage calculator?
Five modes in one tool
Everything from basic percentage-of calculations to percentage change and increase/decrease — all in one place.
Live results
Results update as you type. No button presses, no waiting. Change a number and the answer changes instantly.
Quick percentage buttons
Common percentages like 5%, 10%, 15%, 18%, 20%, 25%, and 50% are one tap away. Perfect for GST, tips, and discounts.
Color-coded change
Percentage change results are color-coded: green for increases, red for decreases. See the direction at a glance.
Completely private
Your numbers never leave your device. No server, no logs, no data stored anywhere.
Works offline
Once the page loads, the calculator works without an internet connection. Perfect for shopping or working offline.
The five percentage modes explained
1. What is X% of Y?
This is the most common percentage question. You have a percentage and a number, and you want to find the result. For example: "What is 15% of 200?" The answer is 30.
Formula: Result = (X ÷ 100) × Y
When to use it: Calculating discounts ("25% off a $80 item"), tips ("18% of a $50 bill"), tax ("8% sales tax on $120"), or any situation where you know the percentage and the base number.
2. X is what % of Y?
This is the reverse. You have two numbers and you want to know what percentage the first is of the second. For example: "30 is what percent of 200?" The answer is 15%.
Formula: Result = (X ÷ Y) × 100
When to use it: Checking test scores ("I got 85 out of 100 — what's that as a percentage?"), comparing values ("This month's sales are $45,000 out of a $200,000 target"), or understanding proportions.
3. Percentage Change
This calculates the percentage increase or decrease between two values. For example: "From 100 to 125 — what's the percentage change?" The answer is +25%.
Formula: Result = ((New − Old) ÷ |Old|) × 100
When to use it: Tracking price changes, comparing month-over-month sales, measuring growth or decline, or any situation where you need to know how much something has changed relative to where it started.
A positive result means an increase; a negative result means a decrease. The result panel shows this with color coding — green for increases, red for decreases.
4. Increase a number by a percentage
This adds a percentage to a number. For example: "Increase 200 by 15%" gives 230.
Formula: Result = X × (1 + Y ÷ 100)
When to use it: Adding GST or sales tax to a price, applying a markup, calculating a raise, or any situation where you need to add a percentage to a base value.
5. Decrease a number by a percentage
This subtracts a percentage from a number. For example: "Decrease 200 by 15%" gives 170.
Formula: Result = X × (1 − Y ÷ 100)
When to use it: Applying a discount, calculating a sale price, subtracting tax, or any situation where you need to reduce a value by a percentage.
Real-world uses for percentage calculations
Shopping and discounts
A jacket is priced at $120 and it's 30% off. What's the final price? Use the decrease mode: $120 decreased by 30% = $84. You save $36.
You want to double-check that a store's "25% off" sign is being applied correctly. Use the decrease mode on the original price and compare.
GST and sales tax
A service costs $850 and GST is 18%. What's the total? Use the increase mode: $850 increased by 18% = $1,003. The GST amount is $153.
You have a total of $1,180 that includes 18% GST and you want to find the pre-tax price. Use the decrease mode in reverse — or just divide by 1.18. The original was $1,000.
Tips and restaurant bills
A restaurant bill is $64.50 and you want to leave a 20% tip. Use the "X% of Y" mode: 20% of $64.50 = $12.90. The total would be $77.40.
Exam scores and grades
You scored 78 out of 90 on a test. What's your percentage? Use the "X is what % of Y" mode: 78 is 86.67% of 90.
Your final grade is weighted: exams are 60%, coursework is 40%. You got 75% on exams and 88% on coursework. Use the "X% of Y" mode for each component, then add them: (75 × 0.60) + (88 × 0.40) = 45 + 35.2 = 80.2% overall.
Business and finance
Revenue was $48,000 last quarter and $56,000 this quarter. What's the growth rate? Use the percentage change mode: from $48,000 to $56,000 = +16.67%.
A product costs $32 to make and you want a 45% profit margin. What should the selling price be? Use the increase mode: $32 increased by 45% = $46.40.
Health and fitness
You weighed 180 lbs and now weigh 165 lbs. What's the percentage change? Use the change mode: from 180 to 165 = −8.33%, meaning you lost 8.33% of your body weight.
A food label says a serving has 12g of fat and your daily target is 65g. What percentage of your daily value is that? Use the "X is what % of Y" mode: 12 is 18.46% of 65.
Everyday math
Your phone battery is at 47% and you want to know how many hours that is if a full charge lasts 14 hours. Use the "X% of Y" mode: 47% of 14 = 6.58 hours.
A recipe calls for 250g of flour and you want to make 75% of the recipe. Use the "X% of Y" mode: 75% of 250 = 187.5g.
Tips for working with percentages
- Percentages are reversible for multiplication. 15% of 200 is the same as 200% of 15. Both equal 30. This trick can make mental math easier.
- "Percent" literally means "per hundred." So 15% is just 15 per 100, or 0.15 as a decimal. Multiplying by 0.15 gives the same result as the percentage formula.
- Percentage change uses the absolute value of the old number. This handles negative starting values correctly. Going from −10 to +10 is a 200% increase, not a −200% change.
- Percentage points vs percentage change. If interest rates go from 3% to 4%, that's a 1 percentage point increase but a 33.3% percentage change. Be careful which one you mean.
- Successive percentages don't add. A 20% discount followed by a 10% discount is not 30% off. It's 28% off, because the second discount applies to the already-reduced price.
- Use the quick buttons for common rates. GST rates (5%, 12%, 18%, 28%), standard tips (15%, 18%, 20%), and common discounts (10%, 25%, 50%) are all one tap away in the "X% of Y" mode.