Sumwise

Percentage Change from 100 to 80

From 100 to 80 is a 20% decrease

Change
-20%
Difference
-20
New ÷ old
0.8
Direction
decrease

Sumwise · Maintained by Theo Abbott (pen name) · automated checks · Data: exact arithmetic; unit definitions from NIST SP 811 · Updated · How the checks work

How to work it out

  1. Difference: 80 − 100 = -20
  2. Divide by the starting value: -20 ÷ 100 = -0.2
  3. Multiply by 100: -20%
  4. Check: Work forwards from the start: 100 × (1 − 0.2) = 100 × 0.8 = 80.

In a spreadsheet: =(80-100)/100*100. Always divide by the starting value, not the new one. A rise from 40 to 50 is +25%, but the fall from 50 back to 40 is −20%.

What the result means

The new value is 80% of the old one: for every 100 at the start there are now 80, so 20 out of every 100 have gone.

Sales: a price cut from $100 to $80 is a 20% discount.

Why the change back is different

A 20% fall followed by a 20% rise does not bring you back to 100: it gives 96. The second percentage is taken of 80, not of 100, so to undo this change you need 25% instead.

Related results

Results for nearby numbers
100 to 78

From 100 to 78 is a 22% decrease

100 to 79

From 100 to 79 is a 21% decrease

100 to 81

From 100 to 81 is a 19% decrease

100 to 82

From 100 to 82 is a 18% decrease

100 to 90

From 100 to 90 is a 10% decrease

The other way round: Percentage change from 80 to 100. Percentage change is not symmetric: from 100 to 80 is -20%, but from 80 back to 100 is 25%, because the starting value is the base. For a comparison that is the same both ways, use the percentage difference between 80 and 100: 22.2222%. See Percentage difference between 80 and 100.

Practice

19 to 82
Show answer

From 19 to 82 is a 331.5789% increase

63 to 32
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From 63 to 32 is a 49.2063% decrease

31 to 67
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From 31 to 67 is a 116.129% increase

99 to 25
Show answer

From 99 to 25 is a 74.7475% decrease

24 to 25
Show answer

From 24 to 25 is a 4.1667% increase

74 to 79
Show answer

From 74 to 79 is a 6.7568% increase

Calculate another

How answers are calculated and checked: methodology.

Questions

Percentage Change from 100 to 80

Going from 100 to 80 is a 20% decrease. Formula and steps.

Is going from 100 to 80 an increase or a decrease?

A decrease: the value fell by 20, which is 20% of the starting value.

What is the percentage change from 80 back to 100?

25%. It is a different number because the starting value is now 80, not 100.