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Percentage Calculator

Tools

Eight percentage calculations in one tool — find percent of a value, increase, decrease, original value, and more.

Pick the calculation you need from the chips above. Each mode is a focused two-input form — type the numbers, hit Calculate, and the result appears below. Inputs accept either decimal style (1,234.56 or 1.234,56) and the result is formatted in your locale.

Pick a calculation

What is X% of a value?

Formula: X% × Y / 100

X is what percentage of Y?

Formula: (X / Y) × 100

Percentage increase from X to Y

Formula: ((Y − X) / X) × 100

Percentage decrease from X to Y

Formula: ((X − Y) / X) × 100

Add X% to a value

Formula: Y + (Y × X / 100)

Subtract X% from a value

Formula: Y − (Y × X / 100)

Original value before a +X% increase

Formula: Y / (1 + X/100)

Percentage difference between two values

Formula: |X − Y| / ((X + Y) / 2) × 100

What this calculator does

  • How much is X% of a value — quick percent-of-amount lookup.
  • Value is what percentage of another — see exactly what slice a number represents.
  • Percentage increase — compare a starting and final value.
  • Percentage decrease — same idea, in the opposite direction.
  • Add a percentage — apply a markup, tax, or interest to a value.
  • Subtract a percentage — apply a discount or deduction.
  • Original value before an increase — back out the pre-bump number from the post-bump one.
  • Difference between two values — symmetric, sign-free comparison.

How to use it

Pick a mode from the chips at the top. Each mode shows you the formula it's using under the inputs, so you can double-check the math or learn it as you go. Hit Calculate and the result fades in. Tweak either input afterwards and the result re-computes live, no extra click needed.

Why an online calculator?

Doing percentages by hand is fast for round numbers and slow-and-error-prone for everything else. This tool covers the eight cases that come up daily — discounts, taxes, shop margins, school problems, splitting a bill — without you having to remember which formula goes where.

Who uses this

  • Students working through math homework.
  • Shop owners checking margins, markups, and discounts.
  • Anyone reading a news headline that mentions a percentage and wants to sanity-check it.