Four calculators in one. Calculate instantly, understand visually, and learn the mental shortcuts that make percentages feel obvious.
Pick the mode that matches your question. Formula shown with result.
Most people memorize the formula. This is what makes it click instead.
“Per cent” literally means per hundred. A percentage is a ratio expressed in hundredths.
Imagine a crowd of exactly 100 people. If 30% like coffee, that means 30 of those 100 people do. Now scale the crowd: 500 people? 30% = 150 people. 1000 people? 300. Percentages are just a consistent scale-invariant ratio— the "/100" is baked in so you can compare things of different sizes fairly.
Cover the value you want — the remaining two tell you how to find it.
See the part-vs-whole relationship in real time.
“The price went from $80 to $100, so it increased by 20%.”
% change = (new − old) ÷ old × 100 = (100 − 80) ÷ 80 × 100
The base matters. 20% of the new value ≠ % change from the old value. Always divide by the starting number.
The tricks that become second nature. Tap any to expand.
Every percentage problem reduces to: multiply or divide by (x/100)
There's really only one formula hiding behind all percentage questions. Convert the percentage to a decimal (÷100), then multiply or divide depending on what you know. The four calculator modes above are just different ways of rearranging the same equation: Part = Rate × Base.
A 30% off tag. ₹2,400 × 0.70 = ₹1,680. You pay the complement, not the discount.
Conversion rates, growth rates, error rates — all percentage changes. The base always matters.
GST, income tax slabs, loan interest — all percentages of different bases. Know which base.
| Question | Formula | Example |
|---|---|---|
| What is 15% of 200? | (15 / 100) × 200 | = 30 |
| 45 is what % of 180? | (45 / 180) × 100 | = 25% |
| 80 → 100, % change? | ((100 − 80) / 80) × 100 | = 25% |
| 60 is 40%, find total | (60 / 40) × 100 | = 150 |