What is Percentage Calculator?

The percentage calculator handles all common percentage operations in one place. Calculate what percent one number is of another, find a percentage of a value, work out a percentage increase or decrease, recover an original price from a sale price, or find the whole when you only know a part.

Ten modes cover the questions that actually come up in daily work: what is 18% of $1,240 (tip and tax), what percent of 320 is 96 (test scores, conversion rates), the percent change from 80 to 100 (price moves, growth rates), $250 plus a 20% raise, $120 minus a 30% discount, a grade of 43 out of 50 with its letter band, and a tip table on an $85 bill at 10/15/18/20/25% with split-per-person totals. Three reverse modes round it out: 45 is 25% of what (find the whole from a part), the original price before a 20% discount turned it into $85, and the symmetric difference between 40 and 60 when neither is the clear baseline. The full equation appears under every result, your last five calculations stack up beneath for easy comparison, and your inputs come back exactly where you left them after a refresh.

How to use

1. Choose your calculation type: percent of a number, what percent, percent change, plus/minus a percent, find the whole from a part, the original before a discount, the difference between two values, a grade from a score, or tip
2. Enter the required values in the input fields for your selected calculation
3. See the result instantly — use the copy button to grab the answer

When to use

• Working out tax, tip, or commission on a single amount.
• Computing test grades, survey response rates, or conversion percentages.
• Comparing two figures to find a percent increase or decrease (price changes, growth, weight loss).

Result

Calculate 15% of 250 to get 37.50 as a tip amount. Or find the percentage change from 80 to 100, which is a 25% increase. Check what percent 45 is of 180 to get 25%.

FAQ

How is percentage change calculated when the starting number is negative?

The calculator uses (new - old) / |old| x 100, so the absolute value of the starting number is the divisor. This keeps the direction of the change correct, going from -50 to -25 shows as a 50% increase, not a 50% decrease.

What's the difference between percent of and what percent?

Percent of asks for a slice of a known number (15% of 250 = 37.5). What percent asks how big one number is relative to another (45 out of 180 = 25%). The first multiplies, the second divides.

Why does going up 50% then down 50% not return me to the start?

Because each percentage is taken from a different base. 100 -> +50% gets you to 150, then -50% takes 75 off that 150 and leaves you at 75. To get back to 100 from 150 you'd need a -33.3% change, not -50%.

Can it handle very small or very precise numbers?

Yes. The result keeps up to four decimal places and trims trailing zeros, so values like 0.0125% or 3.1416% show cleanly. JavaScript's standard number precision (about 15 significant digits) is the underlying limit.

How do I get a markup that gives me a 30% margin?

Margin and markup are different. For a 30% margin on a $70 cost, sell at $100 (cost / (1 - margin)). That's a 42.86% markup over cost. Use 'what percent' to verify: 30 is what percent of 100, the answer is 30%.

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