Percentage Increase and Decrease Calculator
Enter any two numbers and instantly see the percent change, formula, and step-by-step explanation. No signup, no ads, no page reloads.
Enter both values
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Fill in the original and new values to see the result instantly.
Absolute change: — | Factor: —
Optional reverse calculator
Apply a percentage to a value
Result
How it works
Our calculator uses the standard percentage-change formula. It works for price changes, salary raises, population growth, discounts, and any other increase or decrease between two numbers.
Find the difference
Subtract the original value from the new value. A positive result means an increase; a negative result means a decrease.
Divide by the original
Divide the difference by the absolute value of the original number. This gives you the change as a decimal.
Multiply by 100
Convert the decimal to a percentage by multiplying by 100. That is your percent increase or decrease.
Read the explanation
Below the result you will see the formula, the absolute change, and the multiplicative factor.
Common examples
Here are a few quick reference calculations to help you check your own numbers.
- 50 to 75 is a 50% increase.
- 80 to 60 is a 25% decrease.
- 200 increased by 15% becomes 230.
- 200 decreased by 15% becomes 170.
- 100 to 100 is a 0% change.
Frequently asked questions
Answers to the most common questions about percentage increase, decrease, and change.
What is the percentage change formula?
Percentage change = (new value − original value) / |original value| × 100. The result is positive for an increase and negative for a decrease.
How do you calculate percentage increase?
Subtract the original value from the new value, divide by the absolute original value, and multiply by 100. For example, going from 40 to 50 is a 25% increase because (50 − 40) / 40 × 100 = 25.
How do you calculate percentage decrease?
Subtract the new value from the original value, divide by the absolute original value, and multiply by 100. For example, going from 80 to 60 is a 25% decrease because (80 − 60) / 80 × 100 = 25.
Can percentage change be more than 100%?
Yes. If a value grows from 10 to 30, the increase is 200%. A percentage change above 100% simply means the new value is more than double the original.
What does a negative percentage change mean?
A negative percentage change means the value went down. The larger the negative number, the bigger the decrease relative to the original value.
What is the difference between percentage change and percentage difference?
Percentage change compares a new value to an original value and shows direction (increase or decrease). Percentage difference is usually the absolute difference between two values divided by their average, used when neither is clearly the original.
How do I calculate a price increase percentage?
Use the formula (new price − old price) / old price × 100. If a product rises from $20 to $25, the increase is 25%.
How do I increase a number by a percentage?
Multiply the number by 1 plus the percentage as a decimal. To increase 100 by 20%, calculate 100 × 1.20 = 120.
What is a good percentage increase for a salary raise?
Typical annual raises range from 3% to 5%, though promotions or role changes can be much larger. Use the calculator to compare your new salary to your old one.
How do I calculate sales growth percentage?
Subtract last period sales from current sales, divide by last period sales, and multiply by 100. If sales grew from $5,000 to $6,500, growth is 30%.
How do I calculate percent improvement?
Percent improvement uses the same increase formula: (new − old) / |old| × 100. It is often used for test scores, speed, or efficiency metrics.
How do I calculate a percentage discount?
Subtract the sale price from the original price, divide by the original price, and multiply by 100. A $100 item marked down to $75 is a 25% discount.
How do I decrease a number by a percentage?
Multiply the number by 1 minus the percentage as a decimal. To decrease 100 by 15%, calculate 100 × 0.85 = 85.
What is percentage off?
"Percentage off" is another way to say percentage decrease, usually in a shopping context. It tells you how much the price was reduced.
How do I calculate percent loss?
Use (original value − new value) / original value × 100. If an investment drops from $1,000 to $800, the loss is 20%.
How do I calculate percentage reduction?
Percentage reduction is the same as percentage decrease: (original − new) / original × 100. It is common in budgets, emissions, and weight tracking.
Is this calculator free to use?
Yes. The calculator is completely free, runs entirely in your browser, and does not require an account or email address.
Does the calculator store my numbers?
No. All calculations happen in your browser. Nothing you type is sent to our server or stored anywhere.
Can I use this on my phone?
Yes. The page is responsive and works on phones, tablets, and desktop browsers. The numeric keyboard appears automatically on mobile.
Why does the toggle switch move automatically?
The switch suggests whether your numbers represent an increase or a decrease. You can also click it manually to view the opposite direction.
How accurate is the result?
The calculator uses standard floating-point arithmetic and rounds to a reasonable number of decimal places. For most everyday purposes, the result is accurate enough.
Can I use this for financial decisions?
This tool performs mathematical calculations only. It is not financial, investment, tax, or legal advice. Consult a qualified professional for decisions that affect your money or obligations.
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