U.S. inflation rate in 1921: -10.50%

Inflation in 1921 and its effect on dollar value

$1 in 1920 is equivalent in purchasing power to about $0.89 in 1921. The dollar had an average deflation rate of -10.50% per year since 1920, producing a cumulative price change of -10.50%. Purchasing power increased by 10.50% in 1921 compared to 1920. On average, you would have to spend 10.50% less money in 1921 than in 1920 for the same item. This is an example of deflation.

This means that prices in 1921 are 10.5% lower than average prices since 1920, according to the Bureau of Labor Statistics consumer price index.

The 1920 inflation rate was 15.61%. The inflation rate in 1921 was -10.50%. The 1921 inflation rate is lower compared to the average inflation rate of 2.76% per year between 1921 and 2021.

Inflation rate is calculated by change in the consumer price index (CPI). The CPI in 1921 was 17.90. It was 20.00 in the previous year, 1920. The difference in CPI between the years is used by the Bureau of Labor Statistics to officially determine inflation. Because the 1921 CPI is less than 1920 CPI, negative inflation (also known as deflation) has occurred.

Inflation from 1920 to 1921
Average inflation rate -10.50%
Converted amount ($1 base) $0.89
Price difference ($1 base) $-0.11
CPI in 1920 20.000
CPI in 1921 17.900
Inflation in 1920 15.61%
Inflation in 1921 -10.50%
$1 in 1920 $0.89 in 1921

USD Inflation since 1913
Annual Rate, the Bureau of Labor Statistics CPI

Inflation by City

Inflation can vary widely by city, even within the United States. Here's how some cities fared in 1920 to 1921 (figures shown are purchasing power equivalents of $1):

San Francisco, California experienced the highest rate of inflation during the 1 years between 1920 and 1921 (-7.98%).

Atlanta, Georgia experienced the lowest rate of inflation during the 1 years between 1920 and 1921 (-11.45%).

Note that some locations showing 0% inflation may have not yet reported latest data.

Inflation by Country

Inflation can also vary widely by country. For comparison, in the UK £1.00 in 1920 would be equivalent to £0.91 in 1921, an absolute change of £-0.09 and a cumulative change of -8.70%.

In Canada, CA$1.00 in 1920 would be equivalent to CA$0.84 in 1921, an absolute change of CA$-0.16 and a cumulative change of -16.07%.

Compare these numbers to the US's overall absolute change of $-0.11 and total percent change of -10.50%.

Inflation by Spending Category

CPI is the weighted combination of many categories of spending that are tracked by the government. Breaking down these categories helps explain the main drivers behind price changes. This chart shows the average rate of inflation for select CPI categories between 1920 and 1921.

Compare these values to the overall average of -10.50% per year:

Category Avg Inflation (%) Total Inflation (%) $1 in 1920 → 1921
Food and beverages 0.00 0.00 1.00
Housing 0.00 0.00 1.00
Apparel -26.11 -26.11 0.74
Transportation 0.00 0.00 1.00
Medical care 0.00 0.00 1.00
Recreation 0.00 0.00 1.00
Education and communication 0.00 0.00 1.00
Other goods and services 0.00 0.00 1.00

For all these visualizations, it's important to note that not all categories may have been tracked since 1920. This table and charts use the earliest available data for each category.

How to Calculate Inflation Rate for $1, 1920 to 1921

Our calculations use the following inflation rate formula to calculate the change in value between 1920 and 1921:

CPI in 1921 CPI in 1920
1920 USD value
1921 USD value

Then plug in historical CPI values. The U.S. CPI was 20 in the year 1920 and 17.9 in 1921:


$1 in 1920 has the same "purchasing power" or "buying power" as $0.89 in 1921.

To get the total inflation rate for the 1 years between 1920 and 1921, we use the following formula:

CPI in 1921 - CPI in 1920CPI in 1920
Cumulative inflation rate (1 years)

Plugging in the values to this equation, we get:

17.9 - 2020

Comparison to S&P 500 Index

To help put this inflation into perspective, if we had invested $1 in the S&P 500 index in 1920, our investment would be nominally worth approximately $0.95 in 1921. This is a return on investment of -5.23%, with an absolute return of $-0.05 on top of the original $1.

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 -11.73% of returns ($-0.11) during this period. This means the inflation-adjusted real return of our $1 investment is $0.06. You may also want to account for capital gains tax, which would take your real return down to around $0 for most people.

Investment in S&P 500 Index, 1920-1921
Original Amount Final Amount Change
Nominal $1 $0.95 -5.23%
Inflation Adjusted
$1 $1.06 5.89%

Information displayed above may differ slightly from other S&P 500 calculators. Minor discrepancies can occur because we use the latest CPI data for inflation, annualized inflation numbers for previous years, and we compute S&P price and dividends from January of 1920 to latest available data for 1921 using average monthly close price.

For more details on the S&P 500 between 1920 and 1921, see the stock market returns calculator.

News headlines from 1920

Politics and news often influence economic performance. Here's what was happening at the time:

  • The League of Nations' first assembly takes place in Paris.
  • The British Parliament passes the Fourth Home Rule Act, dividing Ireland into two parts and leading to a yearlong Anglo-Irish war in the southern counties.
  • The Catholic Church canonizes Joan of Arc, formally making her a saint.
  • The 19th Amendment to the constitution is ratified, granting U.S. woman suffrage for the first time.

Data Source & Citation

Raw data for these calculations comes from the Bureau of Labor Statistics' (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: “Inflation Rate in 1921 | Inflation Calculator.” Official Inflation Data, Alioth Finance, 27 Jul. 2021, https://www.officialdata.org/inflation-rate-in-1921.

Special thanks to QuickChart for their chart image API, which is used for chart downloads.

in2013dollars.com is a reference website maintained by the Official Data Foundation.

Ian Webster

About the author

Ian Webster is an engineer and data expert based in San Mateo, California. He has worked for Google, NASA, and consulted for governments around the world on data pipelines and data analysis. Disappointed by the lack of clear resources on the impacts of inflation on economic indicators, Ian believes this website serves as a valuable public tool. Ian earned his degree in Computer Science from Dartmouth College.

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» Read more about inflation and investment.

Inflation from 1920 to 1921
Average inflation rate -10.50%
Converted amount ($1 base) $0.89
Price difference ($1 base) $-0.11
CPI in 1920 20.000
CPI in 1921 17.900
Inflation in 1920 15.61%
Inflation in 1921 -10.50%
$1 in 1920 $0.89 in 1921