How to use the calculator
- Enter the cash amount and the From and To months (any month since July 1954).
- Choose Money market for cash that earns interest, or Cash, no interest for a checking account or cash at home.
- Under More options, set the fee below the Fed funds rate, the tax on interest, and a stock or ETF to compare (SPY by default).
How it works
each month: cash = cash × (1 + (Fed funds rate − fee) × (1 − tax) / 12)
needed to keep up = amount × CPI(month) / CPI(From)
real value = cash / (CPI(To) / CPI(From))Money market funds invest in overnight loans and Treasury bills, so their yield closely follows the federal funds rate, minus the fund’s expenses. The calculator uses each month’s effective federal funds rate from the Federal Reserve, minus the fee you set (0.3% by default), and US CPI-U inflation from the Bureau of Labor Statistics.
Example: $10,000 in a money market fund, September to September
| Period | Cash grew | Prices rose | Real result a year |
|---|---|---|---|
| 1976–2026 (50 years) | ×8.83 | ×5.85 | +0.83% |
| 1996–2026 (30 years) | +90.7% | +113.5% | −0.38% |
| 2006–2026 (20 years) | +34.2% | +66.1% | −1.06% |
| 2016–2026 (10 years) | +24.3% | +39.6% | −1.15% |
Cash kept up with inflation in the high-rate 1980s and 1990s but has lost buying power since the 2008 financial crisis, when rates stayed near zero for years. Even when cash beats inflation, a stock index has usually done far better over long periods, with much bigger swings along the way.
When cash makes sense
- An emergency fund and money needed within a few years belong in cash, whatever the real return.
- High-rate periods such as 2023–2025 paid a real return on cash.
- Long-term savings left in cash usually fall behind; see the real return calculator for stocks and ETFs.
Cash, money market funds and savings accounts
- Money market funds hold short-term government and company debt and pay close to the Fed funds rate, less their expenses.
- High-yield savings accounts usually pay a little less than money market funds and change their rates more slowly.
- Checking accounts and cash pay little or nothing, so they lose buying power whenever prices rise; choose Cash, no interest to see how much.
Frequently asked questions
Does cash keep up with inflation?
Sometimes. A money market fund roughly beat inflation in the 1980s and 1990s, when interest rates were high, but lost buying power for most of 2009–2022, when rates were near zero. Cash that earns no interest always loses to inflation when prices rise.
How is the money market return estimated?
From each month’s effective federal funds rate, minus a fee (0.3% a year by default), compounded monthly. Money market fund yields follow the Fed funds rate closely; set the fee to match your fund or bank.
Why does the calculator start in July 1954?
That is when the Federal Reserve’s effective federal funds rate series starts.
What about taxes?
Interest on cash is usually taxed as ordinary income. Enter your tax rate under More options; taxes make it harder for cash to keep up with inflation.
What does the comparison ticker show?
What the same amount would have grown to in that stock or ETF over the same months, with dividends reinvested, before and after inflation.
Can I put this calculator on my website?
Yes. It is free for any site. Use the embed code generator at the bottom of this page, copy the code and paste it into your page. Please keep the credit line with the two links under the calculator.
Related calculators
- Real Return Calculator (Inflation-Adjusted)The return of any US stock or ETF after inflation between two months, in total and per year.
- Fed Funds Rate HistoryThe federal funds rate since 1954, today’s target range and every Fed hike and cut since 1982.
- Historical Inflation CalculatorWhat an amount from any year or month since 1913 is worth in another, from official US CPI data.
- Compound Interest CalculatorHow a starting amount and monthly savings grow over time, after fees, tax drag and inflation.
See all free investing calculators, or add live stock quotes to your site with the free stock widgets.
Add this calculator to your website
The calculator is free to embed on any website, personal or commercial, and works on WordPress, Blogger, Wix, Squarespace, Webflow, Ghost and plain HTML. Choose the options, copy the code and paste it into your page.
Preview: this is how the calculator and the credit line will look on your page
Free for personal and commercial websites. Please keep the “by Quotelinks” credit line under the calculator visible and unchanged, and don’t modify the calculator or present it as your own. The <script> line is optional: it sizes the frame to fit the calculator; if your platform removes scripts, the calculator still works at the fixed height. Money market returns are estimated from the federal funds rate; actual fund and bank rates differ. Past results don’t predict future results. For illustration only, not financial advice.