Investor.gov defines real return as investment return after accounting for inflation and taxes, while nominal return does not subtract those effects. A Coast FIRE calculator may use a more specific modeled definition depending on whether it separately includes fees or taxes.
What Is a Nominal Return?
Nominal Return
A nominal return is the investment-growth rate before adjusting for inflation.
A nominal return is the investment-growth rate before adjusting for inflation.
For example:
7% nominal return
means the model assumes the portfolio grows by 7% per year before an inflation adjustment.
Nominal values answer a question such as:
How many dollars could the portfolio contain in the future?
But a future dollar may not have the same purchasing power as a dollar today.
The U.S. Bureau of Labor Statistics explains that when prices rise, the purchasing power of a dollar declines.
What Is a Real Return?
A real return adjusts nominal growth for inflation.
It is designed to express growth in purchasing-power terms.
The exact relationship between nominal return and inflation is:
For example:
Nominal return: 7%
Inflation: 3%
produces:
So 7% nominal growth with 3% inflation is not exactly 4% real growth.
The Federal Reserve’s educational material uses the simpler relationship of nominal rate minus inflation to introduce the concept of real rates, while also explaining that real rates account for inflation and purchasing power.
Is Real Return Just Nominal Return Minus Inflation?
A common shortcut is:
Using 7% nominal growth and 3% inflation:
7% − 3% = 4%
The exact calculation gives:
3.88%
The difference is small for one year.
But Coast FIRE calculations often span several decades, so a calculator can use the exact relationship rather than the subtraction shortcut.
This exact-vs-approximate distinction also appears frequently in Bogleheads discussions about retirement calculations and inflation-adjusted returns.
How Does This Site Calculate Real Return?
This site models nominal return, investment fees, and inflation separately.
Its current real-growth calculation is:
Using the current editable defaults:
- nominal return: 7%
- inflation: 3%
- modeled investment fees: 0.10%
produces approximately:
That 3.79% is a calculated scenario result.
It is not a forecast of future investment performance.
The calculator’s exact production methodology is documented on the Assumptions & Methodology page.
Why Do Today’s Dollars Matter in Coast FIRE?
Coast FIRE often begins with an annual retirement-spending estimate expressed in today’s purchasing power.
Suppose the example retirement spending is:
and the modeled retirement target is:
$1.25 million in today’s dollars
If the future portfolio is also displayed in today’s dollars, the growth rate used for that comparison needs to reflect inflation.
That is why many Coast FIRE calculators use a real-return framework.
Several current Coast FIRE tools explicitly describe their outputs as “today’s dollars” and use an inflation-adjusted return for the Coast calculation.
Today’s Dollars vs Future Dollars
The difference can be shown with one mathematical example.
Assume:
- retirement target today: $1,250,000
- retirement in: 35 years
- nominal return: 7%
- inflation: 3%
- no fee adjustment in this simplified comparison
There are two consistent ways to model it.
Method 1: Today's Dollars
Use the $1.25 million target directly.
Convert the 7% nominal return and 3% inflation assumption into a real return:
Then discount the $1.25 million target over 35 years.
Method 2: Future Dollars
First inflate the $1.25 million retirement target for 35 years at 3%.
Future-dollar retirement target:
Then discount that future-dollar amount using the full 7% nominal growth rate.
Can You Mix Nominal Returns With Today’s-Dollar Spending?
Consider:
Retirement target: $1.25 million in today’s dollars
Return: 7% nominal
If the calculator discounts the today-dollar target directly at 7% without first converting the growth rate to real terms—or without inflating the target—it mixes two different dollar frameworks.
That can produce a different Coast FIRE result.
This is one reason users report different answers across Coast FIRE calculators.
Bogleheads discussions contain the same question: if a future goal is stated in today’s dollars, does the required growth rate need to be real or nominal? The recurring answer is that the return and dollar framework need to be consistent.
Why Do Coast FIRE Calculators Give Different Real Returns?
Different calculators use different input designs.
One calculator may ask for: Nominal return + inflation
Another may ask directly for: Real return
Another may also model: investment fees
For example, current Coast FIRE tools use several approaches:
| Calculator Approach | Return Input | Inflation Treatment |
|---|---|---|
| Nominal-input model | Nominal return | Converted separately |
| Real-input model | Real return | Already reflected |
| Today's-dollar model | Real growth | Dollar values kept in current purchasing power |
| Future-dollar model | Nominal growth | Spending/target inflated forward |
Current Coast FIRE calculators from coastfire.info, anbalabs, QuietCalc, CoastVest, and others explicitly use real-return calculations or today-dollar frameworks, although their exact implementation details differ.
That does not mean one percentage can be compared directly with another without checking its definition.
Is 7% Nominal the Same as 7% Real?
Before inflation adjustment
After inflation adjustment
A 7% nominal return is measured before inflation.
A 7% real return represents 7% growth after the inflation adjustment.
With 3% inflation, a 7% nominal return corresponds to approximately:
3.88% real return
before considering any modeled investment fees.
This distinction appears repeatedly in Coast FIRE discussions. In a July 2026 r/coastFIRE thread, a user described 10% return minus 3% inflation as 7% real return and asked what other people use. Another June 2026 thread explicitly asked about long-term nominal return assumptions.
Those discussions identify real user confusion. They do not establish which return assumption is appropriate.
Does Inflation Reduce the Number of Dollars in the Account?
A portfolio can increase in nominal dollars while its purchasing power increases more slowly.
For example, imagine:
Starting amount: $100
Nominal growth: 7%
Ending account value: $107
If prices also rose during that period, the purchasing-power increase represented by $107 would be less than the nominal 7% account growth.
The Federal Reserve describes this distinction by explaining that nominal rates do not account for inflation while real rates do.
Can a Portfolio Have a Positive Nominal Return but a Negative Real Return?
Consider a mathematical scenario:
Nominal return: 3%
Inflation: 5%
The account balance increases in nominal terms.
But the exact inflation-adjusted return is approximately: −1.90%
So the number of dollars increased while modeled purchasing power declined.
That distinction is why nominal growth alone does not describe changes in purchasing power.
Real Return Does Not Mean a Guaranteed Return
No return assumption becomes guaranteed because it is expressed in real terms.
A real-return assumption is still an input to a mathematical model.
Actual future:
- investment returns;
- inflation;
- investment fees;
- taxes;
- and market sequences
can differ from the values entered.
This distinction is especially important because Coast FIRE projections may span 20, 30, or 40 years.
Why Does the Real Return Affect the Coast FIRE Number So Much?
Because the Coast FIRE formula applies compound growth over the years until retirement.
Consider the same modeled retirement target: $1.25 million over: 35 years
Changing the real-growth assumption changes how much the model requires today.
A higher real-growth assumption gives the calculation more future compound growth and therefore produces a lower present-value target.
A lower real-growth assumption produces a higher present-value target.
That is a mathematical relationship, not an assessment of which assumption will occur.
Which Is Better for Coast FIRE: Real or Nominal Returns?
Neither framework is inherently better if the calculation is internally consistent.
Two coherent approaches are:
Real-dollar framework
Use:
- today’s-dollar spending;
- today’s-dollar retirement target;
- real investment growth.
Nominal-dollar framework
Use:
- spending inflated into future dollars;
- future-dollar retirement target;
- nominal investment growth.
Both can produce equivalent mathematical results when the same inflation assumptions are applied correctly.
Problems arise when a model combines values from the two frameworks without converting them.
Frequently Asked Questions
What is the difference between nominal and real return in Coast FIRE?▼
Is 7% return before or after inflation?▼
If return is 7% and inflation is 3%, is real return 4%?▼
Should inflation be subtracted from investment return?▼
Should Coast FIRE be calculated in today’s dollars or future dollars?▼
Why is my Coast FIRE number different when I switch calculators?▼
Can real return be negative when nominal return is positive?▼
The Bottom Line
Nominal and real return answer different questions.
describes the change in the number of dollars before adjusting for inflation.
describes growth after accounting for inflation and is useful for comparing purchasing power across time.
For Coast FIRE, the central consistency rule is:
When inflation is handled consistently, those two frameworks can describe the same mathematical scenario.
The problem is not whether a calculator displays the word real or nominal.
The important question is:
Are the return rate, inflation treatment, and dollar values using the same framework?
Research Sources
Used for the definition of real return and the distinction between nominal and inflation-adjusted investment returns.
Used for the relationship between price changes and the purchasing power of the consumer dollar.
Used for educational definitions of nominal and real rates and the role of inflation in purchasing power.
Used for query and terminology research around today’s dollars, future dollars, real-return calculations, and the difference between the subtraction shortcut and the exact relationship. It was not used as primary authority for financial recommendations.