Sumwise

Percentage Change from 20 to 40

From 20 to 40 is a 100% increase

Change
100%
Difference
20
New ÷ old
2
Direction
increase

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: 40 − 20 = 20
  2. Divide by the starting value: 20 ÷ 20 = 1
  3. Multiply by 100: 100%
  4. Check: Work forwards from the start: 20 × (1 + 1) = 20 × 2 = 40.

In a spreadsheet: =(40-20)/20*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 2 times the old one: for every 100 at the start there are now 200. The value has more than doubled.

Prices: an item whose price rises from $20 to $40 has gone up by 100%.

Why the change back is different

A 100% rise followed by a 100% fall does not bring you back to 20: it gives 0. The second percentage is taken of 40, not of 20, so to undo this change you need 50% instead.

Related results

Results for nearby numbers
20 to 38

From 20 to 38 is a 90% increase

20 to 39

From 20 to 39 is a 95% increase

20 to 41

From 20 to 41 is a 105% increase

20 to 42

From 20 to 42 is a 110% increase

20 to 50

From 20 to 50 is a 150% increase

The other way round: Percentage change from 40 to 20. Percentage change is not symmetric: from 20 to 40 is 100%, but from 40 back to 20 is -50%, because the starting value is the base. For a comparison that is the same both ways, use the percentage difference between 20 and 40: 66.6667%. See Percentage difference between 20 and 40.

Practice

4 to 28
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From 4 to 28 is a 600% increase

35 to 38
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From 35 to 38 is a 8.5714% increase

17 to 84
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From 17 to 84 is a 394.1176% increase

42 to 96
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From 42 to 96 is a 128.5714% increase

19 to 23
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From 19 to 23 is a 21.0526% increase

62 to 54
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From 62 to 54 is a 12.9032% decrease

Calculate another

How answers are calculated and checked: methodology.

Questions

Percentage Change from 20 to 40

Going from 20 to 40 is a 100% increase. Formula and steps.

Is going from 20 to 40 an increase or a decrease?

An increase: the value grew by 20, which is 100% of the starting value.

What is the percentage change from 40 back to 20?

-50%. It is a different number because the starting value is now 40, not 20.