Inflation and Real Returns: What Your Money Really Earns
Read the full lesson page, check three ideas, then try its educational activity.
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A real return is what your investment earned after inflation, measured in buying power. The exact formula is (1 + nominal return) ÷ (1 + inflation rate), minus 1. In 2022, Treasury bills returned about 2.09% while consumer prices rose 6.5%, a real loss of about 4.1%. A growing balance can still buy less.
Check your understanding
Question 1
Your savings account paid 1% in a year when the CPI rose 4%. What was your exact real return?
- A gain of 3.0%
- A loss of about 2.9%
- A loss of exactly 3.0%
- A loss of about 5.0%
Show the answer
Answer: B. 1.01 ÷ 1.04 = 0.9712, a real loss of about 2.9%; the subtraction shortcut would say 3.0%.
Question 2
What sets the inflation part of a Series I savings bond’s rate?
- The S&P 500’s return
- The CPI’s change over six months
- The 10 year Treasury yield
Show the answer
Answer: B. Under 31 CFR Part 359, Treasury sets it from the CPI’s six month change and announces new rates each May 1 and November 1.
Question 3
In our 1928 to 2025 calculation, which asset had the lowest real return a year?
- S&P 500 with dividends
- 10 year Treasury bonds
- 3 month Treasury bills
Show the answer
Answer: C. Bills earned about 0.3% a year after inflation, less than bonds at 1.5% and stocks at 6.8%.
Practice this lesson
Enter $10,000 as the amount today, 4.5% as the annual inflation rate and 5 as the number of years. Set the direction to future cost and compare the projected amount with the $12,441 from actual CPI data in our example. Then enter 3% for 30 years and note the cumulative inflation a long retirement has to cover. Save your progress once you have both figures.
Write down what you learned
In your notes, state the idea in your own words, the evidence you checked, and one limitation. Use hypothetical figures or virtual money for any exercise.
Key takeaways
- A real return is your return after inflation: the change in what your money can buy.
- Exact formula: (1 + nominal) ÷ (1 + inflation), minus 1; simple subtraction is a shortcut that errs more as inflation rises.
- The CPI is built from prices collected in 75 urban areas and weighted by what households spend.
- In the 12 months to December 2021 the CPI rose 7.0%; at the 0.06% average savings rate, that meant a real loss of about 6.5%.
- From 1928 to 2025, stocks earned about 6.8% a year after inflation, bonds 1.5% and bills 0.3%.
- I bonds and TIPS tie their payments to the CPI but come with limits; idle cash has no such protection.
AI responses are for educational purposes. Always verify with official course materials.
This lesson teaches a concept. It is general education, not advice about your money. Before you act on anything you learn here, speak to someone licensed.
Sources and reference material
Primary sources and original reference material for the concepts discussed on this page.
- Consumer Price Index, December 2021 (U.S. Bureau of Labor Statistics news release, January 12, 2022)
- Consumer Price Index, June 2022 (U.S. Bureau of Labor Statistics news release, July 13, 2022)
- Consumer Price Index: Overview (U.S. Bureau of Labor Statistics)
- Consumer Price Index for All Urban Consumers: All Items in U.S. City Average, not seasonally adjusted (CPIAUCNS), BLS data via FRED
- National Rate: Savings (SNDR), Federal Deposit Insurance Corporation data via FRED
- Investor Bulletin: Interest Rate Risk (U.S. Securities and Exchange Commission, June 2013)
References added 14 October 2026.
