According to the Bureau of Labor Statistics consumer price index, prices in 2018 are 5.94% higher than prices in 2015. The dollar experienced an average inflation rate of 1.94% per year during this period.
In other words, $20 in 2015 is equivalent in purchasing power to $21.19 in 2018, a difference of $1.19 over 3 years.
The 2015 inflation rate was 0.12%. The inflation rate in 2018 was 2.44%. The 2018 inflation rate is higher compared to the average inflation rate of 0.05% per year between 2018 and 2019.
|Cumulative price change||5.94%|
|Average inflation rate||1.94%|
|Converted amount ($20 base)||$21.19|
|Price difference ($20 base)||$1.19|
|CPI in 2015||237.017|
|CPI in 2018||251.107|
|Inflation in 2015||0.12%|
|Inflation in 2018||2.44%|
This chart shows calculations of buying power equivalence over time for $20 in 2015 (price index tracking began in 1635).
According to the Bureau of Labor Statistics, each of these USD amounts below is equal in terms of what it could buy at the time:
|Year||USD Value||Inflation Rate|
Inflation can vary widely by city, even within the United States. Here's how some cities fared in 2015 to 2018 (figures shown are purchasing power equivalents of $20):
San Diego, California experienced the highest rate of inflation during the 3 years between 2015 and 2018 (4.95%).
Philadelphia, Pennsylvania experienced the lowest rate of inflation during the 3 years between 2015 and 2018 (1.06%).
Note that some locations showing 0% inflation may have not yet reported latest data.
Inflation can also vary widely by country. For comparison, in the UK £20.00 in 2015 would be equivalent to £21.75 in 2018, an absolute change of £1.75 and a cumulative change of 8.77%.
In Canada, CA$20.00 in 2015 would be equivalent to CA$20.68 in 2018, an absolute change of CA$0.68 and a cumulative change of 3.40%.
Compare these numbers to the US's overall absolute change of $1.19 and total percent change of 5.94%.
CPI is the weighted combination of many categories of spending that are tracked by the government. This chart shows the average rate of inflation for select CPI categories between 2015 and 2018.
Compare these values to the overall average of 1.94% per year:
|Category||Avg Inflation (%)||Total Inflation (%)||$20 in 2015 → 2018|
|Used cars and trucks||-2.02||-5.94||18.81|
|Medical care services||2.83||8.74||21.75|
|Medical care commodities||2.46||7.56||21.51|
It's important to note that not all categories may be tracked since 2015. This table and visualization use the earliest available data for each category.
This inflation calculator uses the following inflation rate formula:
Then plug in historical CPI values. The U.S. CPI was 237.017 in the year 2015 and 251.107 in 2018:
$20 in 2015 has the same "purchasing power" or "buying power" as $21.19 in 2018.
To get the total inflation rate for the 3 years between 2015 and 2018, we use the following formula:
Plugging in the values to this equation, we get:
The above data describe the CPI for all items. Also of note is the Core CPI, which measures inflation for all items except for the more volatile categories of food and energy. Core inflation averaged 2.06% per year between 2015 and 2018 (vs all-CPI inflation of 1.94%), for an inflation total of 6.32%.
When using the core inflation measurement, $20 in 2015 is equivalent in buying power to $21.26 in 2018, a difference of $1.26. Recall that for All Items, the converted amount is $21.19 with a difference of $1.19.
In 2015, core inflation was 1.83%.
Chained CPI is an alternative measurement that takes into account how consumers adjust spending for similar items. Chained inflation averaged 1.61% per year between 2015 and 2018, a total inflation amount of 6.32%.
According to the Chained CPI measurement, $20 in 2015 is equal in buying power to $20.98 in 2018, a difference of $0.98 (versus a converted amount of $21.19/change of $1.19 for All Items).
In 2015, chained inflation was -0.12%.
The average inflation rate of 1.94% has a compounding effect between 2015 and 2018. As noted above, this yearly inflation rate compounds to produce an overall price difference of 5.94% over 3 years.
To help put this inflation into perspective, if we had invested $20 in the S&P 500 index in 2015, our investment would be nominally worth approximately $27.59 in 2018. This is a return on investment of 37.97%, with an absolute return of $7.59.
These numbers are not inflation adjusted, so they are considered nominal. In order to evaluate the real return on our investment, we must calculate the return with inflation taken into account.
The compounding effect of inflation would account for 5.61% of returns ($0.43) during this period. This means the inflation-adjusted real return of our $20 investment is $7.17.
|Original Amount||Final Amount||Change|
Politics and news often influence economic performance. Here's what was happening at the time:
Raw data for these calculations comes from the Bureau of Labor Statistics' Consumer Price Index (CPI), established in 1913. Inflation data from 1665 to 1912 is sourced from a historical study conducted by political science professor Robert Sahr at Oregon State University.
You may use the following MLA citation for this page: “$20 in 2015 → 2018 | Inflation Calculator.” U.S. Official Inflation Data, Alioth Finance, 24 Jan. 2019, https://www.officialdata.org/2015-dollars-in-2018?amount=20.