Percentage Calculator
Find percentages and changes, apply a discount or increase, and work backward from a part to its total.
How to use Percentage Calculator
- Choose the calculation that matches your question.
- Enter both values. For percentage change, enter the original value first and the new value second.
- Read the result and formula to see how the calculation works.
What is Percentage Calculator?
A percentage expresses a quantity out of 100. To find X% of Y, multiply Y by X ÷ 100. To express X as a percentage of Y, calculate X ÷ Y × 100. Percentage change compares a new value with its original value, using (new − original) ÷ |original| × 100. Using the original value's magnitude keeps the sign aligned with the direction of change when the original value is negative. To adjust a value, multiply by 1 plus or minus the percentage divided by 100. To recover a total, divide the known part by its percentage and multiply by 100.
- Calculate a percentage of any finite number
- Express one value as a percentage of another
- Calculate percentage increase or decrease
- Apply a percentage adjustment or recover a total from a known part
- See the formula alongside the result
Choose the baseline before choosing the answer
Use Percentage of a number for an amount, Decrease by a percentage for a final discounted value, and Percentage change for a comparison with an original value. The worked examples use different modes deliberately; each load button replaces the mode as well as the numbers.
A rate rising from 10% to 15% gains five percentage points but grows by 50% relative to its original rate. Relative change from zero is undefined. Successive adjustments multiply rather than add: two 20% discounts leave 64% of the starting price, which is a 36% combined reduction.
Worked examples you can try
Each example uses illustrative inputs. Load its named preset in the calculator above, then calculate to compare with the expected result.
Fifteen percent of 200
Use a percentage as a multiplier out of 100.
Mode: Percentage of a number Percentage: 15 · Number: 200
30 15 ÷ 100 × 200 = 30
Take twenty percent off a price
A discount of 40 leaves a final price of 160.
Mode: Decrease by a percentage Original value: 200 · Percentage: 20
160 200 × (1 − 20 ÷ 100) = 160
A rate rises from 10 to 15
A five-percentage-point increase is a 50% relative increase.
Mode: Percentage change Original value: 10 · New value: 15
50% relative increase (15 − 10) ÷ 10 × 100 = 50% The absolute difference between the rates is 5 percentage points.
Learn a little more
Percentages, discounts, and percentage pointsFrequently asked questions
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the absolute value of the original, then multiply by 100. For example, a change from 80 to 100 is a 25% increase. Interpret changes from a negative starting value with care, since conventions vary.
Why can I not use zero as the original value?
Percentage change divides by the original value. Division by zero is undefined, so a change from zero cannot be expressed as a standard percentage change.
Are percentage changes the same as percentage points?
No. A rate moving from 10% to 15% rises by 5 percentage points and by 50% relative to its original value. This calculator reports relative percentage change.
Can I calculate a discount?
Yes. Choose Decrease by a percentage, enter the original price and discount percentage, and calculate the discounted price directly.