Sumwise

Percentage Change from 100 to 20

From 100 to 20 is a 80% decrease

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

In a spreadsheet: =(20-100)/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 20% of the old one: for every 100 at the start there are now 20, so 80 out of every 100 have gone.

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

Why the change back is different

A 80% fall followed by a 80% rise does not bring you back to 100: it gives 36. The second percentage is taken of 20, not of 100, so to undo this change you need 400% instead.

Related results

Results for nearby numbers
100 to 18

From 100 to 18 is a 82% decrease

100 to 19

From 100 to 19 is a 81% decrease

100 to 21

From 100 to 21 is a 79% decrease

100 to 22

From 100 to 22 is a 78% decrease

100 to 30

From 100 to 30 is a 70% decrease

The other way round: Percentage change from 20 to 100. Percentage change is not symmetric: from 100 to 20 is -80%, but from 20 back to 100 is 400%, because the starting value is the base. For a comparison that is the same both ways, use the percentage difference between 20 and 100: 133.3333%. See Percentage difference between 20 and 100.

Practice

20 to 63
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From 20 to 63 is a 215% increase

67 to 23
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From 67 to 23 is a 65.6716% decrease

55 to 51
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From 55 to 51 is a 7.2727% decrease

69 to 73
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From 69 to 73 is a 5.7971% increase

25 to 5
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From 25 to 5 is a 80% decrease

49 to 92
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From 49 to 92 is a 87.7551% increase

Calculate another

How answers are calculated and checked: methodology.

Questions

Percentage Change from 100 to 20

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

Is going from 100 to 20 an increase or a decrease?

A decrease: the value fell by 80, which is 80% of the starting value.

What is the percentage change from 20 back to 100?

400%. It is a different number because the starting value is now 20, not 100.