Percentage Calculator
＋More features: chained changes, canceling a change, reverse-calculating the original value
After several changes in a row, what is the total % change?
Enter successive change rates such as “+10% then −10%” (negative for decreases), separated by commas or line breaks, and this multiplies them into one total change rate.
What % cancels out a change of X%?
A 25% markup is not undone by a 25% discount, so this calculates the reverse % needed to get back to the original value.
Reverse-calculate the original value from the changed value
Find the original value from the value after the change and the % that was applied — for example “it rose 5% to ¥1,050,000; what was it before?” or “it was ¥8,000 after 20% off; what was the list price?”.
“What percent of B is A?” “How much is 20% off?” — this tool does everyday percentage calculations the moment you type the numbers. Use it for shopping discounts, test achievement rates and year-on-year changes.
How to use
- Enter numbers in the calculation you need (① to ③). The moment both fields are filled, the result appears right below that form.
- Examples: “30 points out of 200 — what percent?” → ① / “How much is the discount on ¥4,980 at 20% off?” → ② / “Sales went from 500 to 650 — what % increase?” → ③.
How it is calculated
- ① What percent of B is A = A ÷ B × 100 (e.g. 30 ÷ 200 × 100 = 15%)
- ② X% of A = A × X ÷ 100 (e.g. 4,980 × 20 ÷ 100 = 996)
- ③ Change rate = (B − A) ÷ A × 100 (e.g. (650 − 500) ÷ 500 × 100 = +30%; decreases are negative)
Sources and assumptions
- Simple arithmetic based on the definition of percentages (results rounded to two decimal places).
Assumptions and notes
- The change rate uses the original value A as the base. Note that 500 → 650 (+30%) and 650 → 500 (−23.08%) give different rates.
- The price after an X% discount is “original value − (result of ②)”.
Frequently asked questions
Can I get the price after 20% off directly?
The quickest way is to calculate 80% of the original value in ② (20% off = 80% of the price). Example: ¥4,980 at 20% off is 80% of 4,980 = ¥3,984.
What is the difference from percentage points (pt)?
Going from 10% to 15% is an increase of 5 percentage points, but as a change rate it is (15 − 10) ÷ 10 × 100 = a 50% increase. The two expressions are easily confused when comparing rates, so take care.
Can I enter more than 100%?
Yes. X% in ② accepts up to 10,000% (e.g. 150% of 200 = 300).