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Percentage Calculator
The four percent questions people actually google — percent of a number, X is what percent of Y, percent increase/decrease, and percent difference — answered live, with the formula shown so you can check the math.
Recent results
Nothing yet — the last 5 results you finish typing appear here (this tab only, cleared on reload).
How it works
Choose which of the four percent questions you are asking.
Results update as you type — nothing is submitted, nothing is stored.
The substituted equation sits under every result, ready to copy.
The four questions, and the formula behind each
Every answer is plain arithmetic you can reproduce on paper.
“What is 20 percent of 150?”
result = value × percent ÷ 100“30 is what percent of 150?”
percent = X ÷ Y × 100“150 plus 20 percent, or minus 20 percent.”
result = value × (1 + percent ÷ 100)“How far apart are 150 and 200, relative to their average?”
diff = |A − B| ÷ ((A + B) ÷ 2) × 100Choose 0–6 decimal places; values round half-up like a receipt.
0.005 → 0.01 at 2 dpNegative percents mean a decrease, and dividing by zero is caught with a plain-English message instead of an error.
FAQ
Do I need to sign up or pay?
No. There is no account, no email, and no limit — the page works as many times as you like.
What is the difference between percent change and percent difference?
Percent change divides by the starting value and has a direction (an increase or a decrease). Percent difference divides by the average of the two numbers, so 150 → 200 and 200 → 150 give the same 28.57% figure.
Can I use it for tips, tax, or discounts?
Yes. Use the percent-of tab for a tip or sales tax (20% of 150 is 30) and the increase/decrease tab for a discount, where a negative percent removes the amount.
Is my data sent anywhere?
No. Every calculation runs in your browser and the recent-results list lives only in this tab, cleared when you reload.
How accurate are the results?
They use standard rounding half-up at the decimal places you choose, so a long decimal like 33.333… becomes 33.33 at two places.