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About Percentage Calculator – Change, Tip & Discount
A percentage is a fraction of 100, and the same handful of percentage calculations come up constantly — working out a tip or a discount, comparing two numbers, or measuring how much something grew or shrank. This percentage calculator bundles those everyday operations into one place so you don't have to remember which way the formula goes.
Find X% of a number, work out what percent one value is of another, measure the percent change between two numbers, or add and subtract a percentage from a value. Every calculation runs instantly in your browser — nothing you type is ever uploaded, so it works offline and keeps your numbers private.
Features
- Find X% of a number, and what percent one value is of another
- Percent change between two numbers — increase or decrease, with sign
- Add or subtract a percentage from a value (markups, discounts, tips)
- Live results, clear plain-language phrasing, and fully offline
How to use
- Enter two numbers — one per line, or separated by a space (e.g. "25 200").
- Pick a calculation: "% of", "is what %", "% change", "add %", or "subtract %".
- Read the result and the plain-English explanation, then copy it.
Frequently asked questions
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 50 out of 200 is (50 / 200) × 100 = 25%. Use the "is what %" mode and enter the two numbers.
How is percent change calculated?
Percent change is (new − old) / old × 100. Going from 100 to 150 is a +50% increase; going from 200 to 150 is a −25% decrease. A positive result means growth, a negative result means a drop.
What does "add 25%" actually do?
It increases the number by that percentage of itself — 200 plus 25% is 250. "Subtract %" does the reverse, so 200 minus 25% is 150. These are handy for markups, discounts, and tax.
Why does it say "can't divide by zero"?
Percent change and "is what %" divide by one of your numbers, so that number can't be zero — there's no meaningful percentage of nothing. Enter a non-zero base value and the result appears.
Does my data get sent anywhere?
No. Every calculation happens locally in your browser. Your numbers never leave your device, and the tool works with the network unplugged.
Related tools
Everything runs locally in your browser — your input is never uploaded.