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Percentage Increase / Decrease Calculator

Add or subtract a percent, % differenceRuns locally · nothing uploaded

Increaseby%
230
Decreaseby%
170
After a% increase it's, what was the original?
100
Percentage difference betweenand
22.2222%

Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100. Use it when neither value is the reference; use percent change when there is a before and after.

Also works as:percentage increase calculatorpercentage decrease calculatorpercentage difference calculatorreverse percentage

How it works

When to use it

  • Increase or decrease a value by a percentage.
  • Find the original value before an increase.
  • Compare two values with no natural baseline (percent difference).

Formula

Increased = value × (1 + p%); decreased = value × (1 − p%)
Original = increased value ÷ (1 + p%)
Percent difference = |A − B| ÷ [(A + B) ÷ 2] × 100%

Worked example

Given: 200 + 15%; 230 after a 15% rise; 40 vs 50

  1. 200 × 1.15 = 230.
  2. 230 ÷ 1.15 = 200.
  3. |40 − 50| ÷ 45 ≈ 22.22%.

Result: 230; 200; about 22.22%.

Reading the result

  • Up 10% then down 10% leaves you at 99, not 100.
  • Don't reverse a 15% rise by taking 15% off (230 × 0.85 = 195.5).

Limitations

  • Use percent difference only when neither value is the reference.

How to use

  1. 1Find the row that matches your question.
  2. 2Enter the number and the percentage.
  3. 3The result appears on the right.

FAQ

How do I add 15% to a number?

Multiply by 1.15. For example, 200 increased by 15% is 200 × 1.15 = 230.

Does +20% then −20% get back to the start?

No. 100 → 120 → 96, because the second percentage applies to a larger base.

Percent change vs percentage difference?

Percent change uses the old value as the base and has a direction. Percentage difference uses the average of the two values, so swapping them gives the same result.

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