Treasury Bills and Bonds: How to Calculate Real Return After Inflation

What Is the Real Return on Treasury Bills and Bonds?#

The real return measures how much an investment actually increases in purchasing-power terms after accounting for inflation.

For example, if an investment generates a nominal return of 25% over one year while prices increase by 15% during the same period, the investor has not gained 25% in real purchasing power.

Part of the nominal return simply compensates for the loss of purchasing power caused by inflation.

This is why evaluating Treasury bills and bonds requires looking at three key figures:

• Nominal return: The stated or advertised return on the investment.

• Inflation rate: The rate at which the general price level increases.

• Real return: The return remaining after accounting for inflation.

What Is the Difference Between Treasury Bills and Treasury Bonds?#

Treasury bills (T-bills) are short-term government securities. They are issued at a discount to their face value and redeemed at face value at maturity. The Central Bank of Egypt publishes T-bill maturities including 91, 182, 273, and 364 days.

Treasury bonds, by contrast, are longer-term government securities. Depending on the issue, they may carry a fixed or variable coupon, or may be issued as zero-coupon securities.

The distinction matters because T-bills and bonds can have different cash-flow structures, maturities, pricing mechanisms, and methods of calculating the investor's effective return.

Therefore, Treasury bills and bonds should not be compared simply by looking at the headline yield. Investors should also consider the investment period, purchase price, cash-flow timing, maturity, and inflation over the relevant period.

Why Is the Nominal Return Not Enough?#

Suppose an investor puts:

EGP 100,000

into an investment generating a nominal annual return of:

25%

After one year, the nominal value becomes:

EGP 100,000 × 1.25 = EGP 125,000

The investor has therefore earned EGP 25,000 in nominal terms.

However, if prices increased by 15% during the same year, the EGP 125,000 at the end of the period does not have the same purchasing power as EGP 125,000 at the beginning.

This is where the real return becomes important.

How Do You Calculate the Real Return After Inflation?#

The more precise formula is:

Real Return = [(1 + Nominal Return) ÷ (1 + Inflation Rate)] − 1

For example:

• Nominal return = 25%

• Inflation = 15%

Therefore:

Real Return = (1.25 ÷ 1.15) − 1

Real Return ≈ 8.70%

So the real return is not simply 10% because 15% inflation cannot be deducted directly from a 25% nominal return when performing the precise calculation.

The investor's purchasing power has increased by approximately 8.70% under these assumptions.

Why Can't You Simply Subtract Inflation From the Return?#

You may sometimes see the following approximation:

Real Return ≈ Nominal Return − Inflation

Using the previous example:

25% − 15% = 10%

This can be useful as a quick approximation, particularly when the percentages are relatively small.

However, it is not the mathematically precise calculation.

For accurate investment analysis, the preferred formula is:

[(1 + Nominal Return) ÷ (1 + Inflation Rate)] − 1

A Practical Example Using Egyptian Treasury Bills#

According to Central Bank of Egypt data for the secondary market on September 30, 2026, weighted-average yields varied depending on the maturity of the Treasury bill.

For example, the weighted-average yield was:

• 24.156% for 3-month T-bills.

• 25.345% for 6-month T-bills.

• 25.121% for 9-month T-bills.

• 25.397% for 12-month T-bills.

These figures represent secondary-market transactions on that date and should not be treated as a guaranteed return available to every investor.

Meanwhile, Egypt's annual urban headline inflation rate stood at 14.5% in August 2026, according to the Central Bank of Egypt. Core inflation was 14.9% during the same month.

If, purely for illustration, we assume a 12-month nominal yield of 25.397% and an inflation rate of 14.5% throughout the same period, the approximate real return would be:

Real Return = (1.25397 ÷ 1.145) − 1

≈ 9.52%

This is an illustrative calculation, not a forecast or guaranteed investment outcome.

Actual real returns will depend on the inflation rate during the investment period, the investor's purchase price, the timing of the investment, applicable costs or taxes, and the actual realized yield.

A Simpler Example: What Happens to EGP 100,000?#

Assume an investor invests:

EGP 100,000

and receives a nominal annual return of:

25%

After one year:

EGP 100,000 × 1.25 = EGP 125,000

Now assume inflation during the same period is:

15%

The purchasing-power equivalent of EGP 125,000, measured in the prices that existed at the beginning of the period, is approximately:

EGP 125,000 ÷ 1.15 = EGP 108,696

This means that the investor's purchasing power increased by approximately:

8.70%

This illustrates the fundamental difference between saying:

"My investment earned 25%."

and saying:

"My investment generated an approximately 8.7% real return after inflation."

How Do You Calculate the Real Return on Treasury Bills?#

Treasury bills require particular attention because they do not necessarily work like a conventional deposit that pays periodic interest.

Treasury bills are issued at a discount and redeemed at face value at maturity. The difference between the purchase price and the amount received at maturity represents the investor's return.

In simplified terms:

Holding-Period Return = (Redemption Value − Purchase Price) ÷ Purchase Price

Once the return for the actual holding period has been calculated, the real return can be estimated using:

Real Return = [(1 + Holding-Period Return) ÷ (1 + Inflation for the Same Period)] − 1

If a quoted yield is annualized while the T-bill has a shorter maturity, investors should not automatically treat the annualized figure as the actual profit earned over the shorter period. The maturity and the convention used to annualize the yield must be taken into account.

What About Treasury Bonds?#

Treasury bonds can work differently because some issues pay a periodic coupon.

For example, the Central Bank of Egypt publishes data for fixed-coupon Treasury bonds, including their maturity, coupon rate, and payment frequency.

However, the coupon rate is not necessarily the same as the investor's actual return.

If a bond is purchased above or below its face value, the investor's effective return can differ from the coupon rate.

For that reason, investors evaluating a Treasury bond should consider:

• Purchase price.

• Face value.

• Coupon rate.

• Coupon payment dates.

• Maturity date.

• Whether the bond may be sold before maturity.

• Yield to maturity, where applicable.

• Inflation over the investment period.

Real Return Depends on Future Inflation, Not Only Current Inflation#

This is one of the most important points when evaluating fixed-income investments.

Suppose an investment offers a nominal annual return of 25% while the current inflation rate is 14.5%.

Using 14.5% in the real-return formula gives you an illustrative calculation based on that inflation assumption.

It does not guarantee that the investor will achieve that real return.

The reason is simple: an investment made today is exposed to the inflation rate that occurs during the investment period, not merely the inflation rate reported at the time of purchase.

This distinction becomes particularly important when inflation is changing over time.

Does a Higher Yield Always Mean a Better Investment?#

Not necessarily.

A higher nominal yield alone is not enough to evaluate an investment.

When comparing fixed-income instruments, investors should consider:

A Common Mistake: Comparing Yield and Inflation Incorrectly#

One of the most common mistakes is saying:

"The investment earns 25% and inflation is 15%, so my real return is 10%."

That is only an approximation.

The more precise calculation is:

(1.25 ÷ 1.15) − 1 = 8.70%

The difference exists because investment returns and inflation compound rather than simply offsetting each other through subtraction.

How Can You Tell Whether Your Investment Is Preserving Your Purchasing Power?#

There are two different questions an investor should ask.

1. Has the nominal value of my money increased?#

If you invested EGP 100,000 and ended up with EGP 125,000, the nominal value increased.

2. Has my purchasing power increased?#

That requires comparing the investment return with inflation.

If the nominal return exceeds inflation, the real return may be positive.

If inflation exceeds the nominal return, the investor's purchasing power may decline even though the nominal amount of money has increased.

What Should You Check Before Buying Treasury Bills or Bonds?#

Before making an investment decision, it is useful to review more than just the headline yield.

Consider:

• The effective yield, rather than relying solely on the advertised rate.

• The investment period.

• The maturity date.

• The purchase price.

• How and when the return is paid.

• Current and expected inflation.

• Whether you may need access to the money before maturity.

• The potential sale price in the secondary market if you need to exit early.

• Any applicable fees, taxes, or other costs.

Conclusion#

Treasury bills and bonds can offer attractive nominal yields, but evaluating an investment requires more than looking at the stated return.

The key measure for understanding the effect of inflation is the real return, which can be calculated using:

Real Return = [(1 + Nominal Return) ÷ (1 + Inflation Rate)] − 1

When the objective is to preserve or increase purchasing power, investors should compare the expected return with inflation over the same investment period, while also considering the purchase price, maturity, cash flows, liquidity, and applicable costs.

Current Central Bank of Egypt data also shows that Treasury bill yields vary according to maturity and market conditions. Therefore, there is no single real-return figure that applies to every Treasury bill or bond investment.

For informational purposes only. This content does not constitute legal advice, financial advice, or a recommendation to buy or sell any financial instrument.