What is the Percentage Difference from 40 to 12?
From 40 to 12 is a 70% decrease
Step by step
- Difference: 12 − 40 = -28
- Divide by the starting value: -28 ÷ 40 = -0.7
- Multiply by 100: -70%
How the answer is worked out
Percentage change measures a difference against the value you started with. The value went from 40 to 12, a difference of 28. Compared with the starting value of 40, that difference is 70%, so this is a 70% decrease.
The new value is 30% of the old one: for every 100 at the start there are now 30, so 70 out of every 100 have gone.
Why calculate this?
Percentage change compares a new value with an old one regardless of size: price rises, growth, discounts, score changes.
- Sales: a price cut from $40 to $12 is a 70% discount.
- Weight: going from 40 to 12 kilograms is a loss of 70% of the starting weight.
- Results: if a team scores 12 points this season after 40 last season, its total has dropped by 70%.
A quicker way
Find 1% of the starting value: 40 ÷ 100 = 0.4. The difference of 28 is 70 of those steps.
Percentage change is not the same as percentage points. If a rate moves from 40% to 12%, it changes by 28 percentage points, but by 70% relative to where it started.
Check the answer
Work forwards from the start: 40 × (1 − 0.7) = 40 × 0.3 = 12. Getting 12 shows the answer is right.
Rounding
Rounded to a whole number the change is -70, to one decimal place -70.0 and to two decimal places -70.00. Round only at the end: rounding halfway through a calculation can change the last digit.
The formula explained
percentage change = (new value − old value) ÷ old value × 100. A positive result is an increase and a negative result is a decrease. The old value is always the base, which is why the change from A to B and from B to A are different percentages.
Another worked example: 8 to 72
- Difference: 72 − 8 = 64
- Divide by the starting value: 64 ÷ 8 = 8
- Multiply by 100: 800%
Why the change back is different
A 70% fall followed by a 70% rise does not bring you back to 40: it gives 20.4. The second percentage is taken of 12, not of 40, so to undo this change you need 233.3333% instead.
Other ways to ask this
The same calculation is often asked in other words. All of these have the answer above:
- Percentage decrease from 40 to 12
- What percent less is 12 than 40?
- 40 to 12 as a percent change
- How much did 40 fall going to 12, in percent?
- Relative change between 40 and 12
Terms used on this page
- Old value: the starting amount, used as the base of the percentage.
- New value: the amount after the change.
- Increase: a positive change: the new value is bigger.
- Percentage point: the plain difference between two rates, not a relative change.
The answer in other forms
| Change | -70% |
|---|---|
| Difference | -28 |
| New ÷ old | 0.3 |
| Direction | decrease |
Related results
| 40 to 10 | From 40 to 10 is a 75% decrease |
| 40 to 11 | From 40 to 11 is a 72.5% decrease |
| 40 to 13 | From 40 to 13 is a 67.5% decrease |
| 40 to 14 | From 40 to 14 is a 65% decrease |
| 40 to 22 | From 40 to 22 is a 45% decrease |
The other way round: Percentage difference from 12 to 40
Doing it in a spreadsheet
In Excel, Google Sheets or Numbers type =(12-40)/40*100 into any cell. Replace the numbers with cell references (for example A1 and B1) to reuse the formula for a whole column.
Common mistakes
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%.
Practice examples
| 8 to 72 | Show answerFrom 8 to 72 is a 800% increase |
| 81 to 28 | Show answerFrom 81 to 28 is a 65.4321% decrease |
| 33 to 52 | Show answerFrom 33 to 52 is a 57.5758% increase |
| 15 to 31 | Show answerFrom 15 to 31 is a 106.6667% increase |
| 52 to 91 | Show answerFrom 52 to 91 is a 75% increase |
| 78 to 2 | Show answerFrom 78 to 2 is a 97.4359% decrease |
| 44 to 82 | Show answerFrom 44 to 82 is a 86.3636% increase |
| 94 to 58 | Show answerFrom 94 to 58 is a 38.2979% decrease |
| 23 to 22 | Show answerFrom 23 to 22 is a 4.3478% decrease |
| 2 to 75 | Show answerFrom 2 to 75 is a 3,650% increase |
How this answer was calculated
The result is worked out from the numbers in this page's address when the page is opened, using exact arithmetic wherever possible and rounding only for display. Nothing is copied from a printed table. If you think an answer is wrong, please tell us through the contact page and we will check it.
Reference this page
Copy a citation or link:
<a href="https://sumwisemath.com/calc/percentage-change/difference-from-40-to-12/">What is the Percentage Difference from 40 to 12?</a>
"What is the Percentage Difference from 40 to 12?". Sumwise. https://sumwisemath.com/calc/percentage-change/difference-from-40-to-12/
Questions
What is the Percentage Difference from 40 to 12?
Going from 40 to 12 is a 70% decrease. Formula and steps.
Is going from 40 to 12 an increase or a decrease?
A decrease: the value fell by 28, which is 70% of the starting value.
What is the percentage change from 12 back to 40?
233.3333%. It is a different number because the starting value is now 12, not 40.
What is the percentage difference between 40 and 12?
When neither value is the starting point, use the average as the base: 28 ÷ 26 × 100 = 107.6923%. That is the symmetric percentage difference.
How do I calculate percentage change in Excel or Google Sheets?
Put the old value in A1 and the new value in B1, then type =(B1-A1)/A1 and format the cell as a percentage. For these numbers it shows -70%.