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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.

Frequently asked questions about percentages

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 20% of 150 is 150 × 20 ÷ 100 = 30.

How do I calculate a percentage increase?

Subtract the original value from the new value, divide the result by the original value and multiply by 100. Going from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase.

How do I find what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example, 45 out of 60 is 45 ÷ 60 × 100 = 75%.

Why doesn't a 10% discount undo a 10% increase?

Because each percentage is applied to a different base. If 100 rises 10% it becomes 110, but 10% off 110 is 11, which brings it to 99, not 100. Use the "original value before an increase" mode to reverse an increase correctly.

What is the difference between percent and percentage points?

Percentage points measure the simple gap between two percentages, while percent measures relative change. A rate going from 10% to 12% rose 2 percentage points, which is a 20% increase.

Is this percentage calculator free?

Yes. It is free, needs no signup and runs entirely in your browser, so you can use it as many times as you want.