Can I use it for consumption tax?

You can, but the tax and discount page fits better. It has the 10% and reduced 8% rates, a choice of floor, round or ceiling for fractions of a yen, and the reverse calculation from a tax-inclusive price. "B% off" here does not round at all, which is not enough to produce an invoice figure.

What about two discounts stacked?

Apply them one after the other. "30% off, then a further 10% off" is not 40% off but 37% off, because 0.7 x 0.9 = 0.63. Put the first answer into the second calculation as the list price. Stacked coupons and member discounts trip this constantly, and the real discount is always the smaller one.

The answer came out negative.

In "percentage change", an after value smaller than the before value is reported as a negative percentage: 100 to 80 is -20%. That is the correct notation; write it up as "a 20% decrease".

What if the base is zero?

The calculation stops and says so. Growth from a base of zero is not mathematically defined, so nothing like "an infinite increase" is displayed. When comparing against a month with zero sales, the absolute difference communicates far better than a ratio would.

Are the numbers I enter stored?

No, and nothing is sent. It all happens in the page and is gone when you close the tab.

Up 20% then down 20% does not return to the start

1000 raised by 20% is 1200; 1200 reduced by 20% is 960, which is 40 short. The 20% going up is 200 out of 1000; the 20% coming down is 240 out of 1200 — different bases. The same trap appears with price rises and cuts, and with tax changes. To get back to the original, use "percentage change" from 1200 to 1000, which is -16.7%.

Do not mix "up by X%" with "now at X%"

"It reached 120%" and "it rose by 120%" are different: the first is 1.2x, the second is 2.2x. English and Japanese both use loose phrasing here, so when reading a report check that both the before and after figures are given. The "percentage change" mode works from the two actual numbers, which removes the ambiguity entirely.

Percent versus percentage point

When approval moves from 40% to 50%, saying "up 10%" is wrong; it is up 10 points. In percent it is a 25% rise, because 10 is 25% of 40. News reports and survey summaries mix the two freely, so the same movement gets written as both 10 and 25. Points for a change in the proportion itself, percent for how much the proportion grew.

Results that do not divide evenly are shown in full. Round once, at the end. Feeding an already-rounded figure into a second calculation stacks the error: in a two-step "find a rate, then apply it" calculation, rounding the first step to one decimal place can shift the final answer by a few percent.

Back to all tools／ Calculators

Percentage Calculator

Runs in your browserNothing is uploaded

Percent questions differ by what you take as the base. Pick one of four questions, enter two numbers, and get the answer together with the formula so you can check it.

Input

What do you want?

Base (A)

Percent (B%)

Output

Enter two numbers and the answer and formula appear here.

Percentage questions change formula depending on which number is the base, so the tool splits them into four separate questions. Picking one fixes the formula, and the working is shown with the answer.

Or type what you want to work out

All tools

Why this one

Four separate questions: "B% of A", "A is what % of B", "percentage change" and "B% off". What trips people up with percentages is not forgetting the formula but mistaking which number is the base. Choosing the question first fixes the base, and from there it is just two numbers.
The working is shown with the answer: The formula appears as used — "1200 x 15 / 100 = 180". That makes it easy to check, and when a quote or a report has to show how a figure was reached, the line can be copied straight across. A calculator that shows only the answer cannot answer "where did this number come from?" later.
The other half is given too: The remainder for "B% of A", the discount itself for "B% off", the absolute difference for a percentage change. Wanting to know "so how much was taken off?" right after getting the percentage is the natural next step, so it is there without retyping anything.

How to use

Pick the question
Each of the four buttons carries an example, such as "what is 15% of 1200?". Choose whichever example is closest to what you want to know.
Enter two numbers
The field labels change to match the question ("list price", "discount rate"). Full-width digits, thousands separators and a trailing currency or % sign are all read correctly.
Read the answer and the working
The result updates as you type. "Copy answer" takes the formula along with the number.

Good to know

Up 20% then down 20% does not return to the start: 1000 raised by 20% is 1200; 1200 reduced by 20% is 960, which is 40 short. The 20% going up is 200 out of 1000; the 20% coming down is 240 out of 1200 — different bases. The same trap appears with price rises and cuts, and with tax changes. To get back to the original, use "percentage change" from 1200 to 1000, which is -16.7%.
Do not mix "up by X%" with "now at X%": "It reached 120%" and "it rose by 120%" are different: the first is 1.2x, the second is 2.2x. English and Japanese both use loose phrasing here, so when reading a report check that both the before and after figures are given. The "percentage change" mode works from the two actual numbers, which removes the ambiguity entirely.
Percent versus percentage point: When approval moves from 40% to 50%, saying "up 10%" is wrong; it is up 10 points. In percent it is a 25% rise, because 10 is 25% of 40. News reports and survey summaries mix the two freely, so the same movement gets written as both 10 and 25. Points for a change in the proportion itself, percent for how much the proportion grew.
Where to round: Results that do not divide evenly are shown in full. Round once, at the end. Feeding an already-rounded figure into a second calculation stacks the error: in a two-step "find a rate, then apply it" calculation, rounding the first step to one decimal place can shift the final answer by a few percent.

FAQ

Can I use it for consumption tax?: You can, but the tax and discount page fits better. It has the 10% and reduced 8% rates, a choice of floor, round or ceiling for fractions of a yen, and the reverse calculation from a tax-inclusive price. "B% off" here does not round at all, which is not enough to produce an invoice figure.
What about two discounts stacked?: Apply them one after the other. "30% off, then a further 10% off" is not 40% off but 37% off, because 0.7 x 0.9 = 0.63. Put the first answer into the second calculation as the list price. Stacked coupons and member discounts trip this constantly, and the real discount is always the smaller one.
The answer came out negative.: In "percentage change", an after value smaller than the before value is reported as a negative percentage: 100 to 80 is -20%. That is the correct notation; write it up as "a 20% decrease".
What if the base is zero?: The calculation stops and says so. Growth from a base of zero is not mathematically defined, so nothing like "an infinite increase" is displayed. When comparing against a month with zero sales, the absolute difference communicates far better than a ratio would.
Are the numbers I enter stored?: No, and nothing is sent. It all happens in the page and is gone when you close the tab.

Input

Output

Related tools

Why this one

How to use

Pick the question

Enter two numbers

Read the answer and the working

Good to know

FAQ