A discount and its real saving
Use increase or decrease with a negative figure to get the sale price directly, then use percentage change on the two prices to confirm the discount actually matches the sign in the window.
Percentage Calculator
Work out percentages, percentage change, and increases or decreases.
Maintained by Roshan.
Use Percentage Calculator
Four different questions get called percentage, and mixing them up is the usual source of a wrong answer. Pick the one you mean.
Percentage change is not symmetricalGoing from 100 to 150 is a 50% increase, but going back from 150 to 100 is a 33.3% decrease, not 50%. The starting figure is the base, so reversing a change never uses the same percentage.
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Browse all finance calculatorsAbout Percentage Calculator
Four genuinely different questions all get called percentage, and confusing them is the usual reason an answer comes out wrong. What is 15% of 200? What percentage of 200 is 30? What is the change from 200 to 250? What is 200 increased by 15%? Those need four different calculations, and a single input box cannot know which you meant. This page keeps them apart, states the answer in words as well as figures, and refuses the cases that have no valid answer instead of returning something confident and wrong. Everything happens in your browser.
Using Percentage Calculator
- Pick the question that matches what you are actually asking. The two input labels change with it, so the boxes always say what belongs in them rather than leaving you to guess which number goes first.
- Type either number and the answer updates immediately, along with a sentence describing it. Reading the result as a sentence is the quickest way to notice you selected the wrong question.
- For percentage change, the first figure is the starting point and the base of the calculation. Swapping the two does not simply flip the sign, which is exactly the trap the sentence is there to catch.
- For an increase or decrease, enter a negative percentage to reduce a figure. Applying minus twenty to a price gives the discounted amount directly.
Where percentage calculator helps
A test score or completion rate
Asking what percentage one number is of another turns 34 out of 40 into a straight percentage without the usual which-way-round hesitation.
Growth between two periods
Enter last month and this month as a change. The sentence states whether it is a rise or a fall, which prevents the classic mistake of reading a decline as growth.
Reversing a change
After a fall, use the change mode with the figures the other way round to see the rise needed to get back. It is always larger than the fall was.
Before you use the result
- Percentage change is not symmetrical, and this catches people constantly. Going from 100 to 150 is a 50% increase, but returning from 150 to 100 is a 33.3% decrease. The base changes, so a rise and the fall that undoes it are never the same percentage. A price cut of 50% needs a 100% rise to recover.
- Percentage points are not percent. If a rate moves from 4% to 6%, that is a rise of two percentage points, or a 50% increase in the rate itself. News reports blur the two routinely, and the difference matters.
- Some cases genuinely have no answer. There is no percentage change from zero, because any increase from nothing is infinite, and nothing can be expressed as a share of zero. Rather than showing Infinity, the tool explains why the question cannot be answered.
- Stacked percentages do not add. A 20% discount followed by a further 10% is not 30% off, it is 28%, because the second reduction applies to the already-reduced price. Apply them one at a time with the increase-or-decrease mode.
Questions about Percentage Calculator
Which option should I choose?
Match it to your sentence. If you would say 'of', pick the first. If you are comparing a part to a whole, pick the second. If you are comparing before and after, pick change. If you are applying a discount or markup, pick increase or decrease.
Why is a 50% rise not undone by a 50% fall?
Because the base differs. The rise is measured against the smaller starting figure and the fall against the larger later one. 100 rises to 150, but half of 150 is 75, not 100.
What is the difference between percent and percentage points?
A move from 4% to 6% is two percentage points, and also a 50% increase in the rate. Both are correct descriptions of the same move, which is why the units have to be stated.
Why do I get an explanation instead of a number sometimes?
Because the question has no valid answer. Change from zero and shares of zero are both undefined, and returning Infinity or a silent zero would be misleading.
Is anything I type recorded?
No. The arithmetic runs in your browser, nothing is transmitted, and nothing is stored between visits.
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