Mathematics · everyday

Percentage Calculator

X% of Y, reverse %, and increase / decrease — same logic as typing in site search.

also try search
15% of 84

What do you need?

Percent (X)

Of (Y)

Answer

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Also useful

Site search (/) accepts the same phrases — e.g. 15% of 84, 84 plus 15%. For tips and bill split see the Tip Calculator.

Using this tool

Percentage patterns

These are the four phrases people type most. The site command palette already understands them; this page is the same arithmetic with labelled fields for search and bookmarks.

What is “percent of”?

X% of Y = (X/100) × Y. So 15% of 84 is 0.15 × 84 = 12.6.

What about “percent off”?

Use decrease by %: final = Y × (1 − X/100). A 15% off coupon on 84 leaves 71.4.

How do I reverse a percentage?

If 21 is what percent of 84: (21/84) × 100 = 25%.

Percent change

From A to B: ((B − A) / A) × 100. From 80 to 100 is +25%.

Reference arithmetic only — not tax, interest, or financial advice.