Percentage Calculator

Three modes, one page — the three questions everyone actually needs to answer.

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X (percent)

Y (number)

X (number)

Y (number)

From

Result

The three modes, explained

X% of Y: the most common question. What's 15% of $200? Answer: 15/100 × 200 = $30. Useful for tips, discounts, tax, commissions.

X is what % of Y: the reverse question. If you got 45 out of 300 on a test, what percent is that? Answer: 45/300 × 100 = 15%. Useful for scores, ratios, market share.

Percent change: the delta between two numbers. Went from 100 to 125? That's a 25% increase. From 100 to 75 is a 25% decrease. Formula: (new − old) / old × 100. Note: percent change is relative to the starting value, so going from 50 to 100 is +100%, but going back from 100 to 50 is only −50% (same absolute change, different percentages).

Common gotcha: percentage points vs. percent

If a rate goes from 4% to 5%, that's a 1 percentage point increase, but a 25% relative increase (1/4 = 25%). News stories frequently confuse these; they mean different things.