Real vs. Nominal Returns
Growth after inflation is what lifestyle feels
A nominal return is the headline number your account grew by. A real return is what is left after inflation, and it is the one that determines whether you can buy more than you could before. Mixing them up is the most common error in long-term planning.
The distinction in one example
Your portfolio grew 8% this year and prices rose 3%. Your nominal return is 8% and your real return is roughly 5%.
Only the 5% represents additional buying power. The other three points were needed just to keep even with rising prices.
In a year when your account grows 2% and inflation runs 4%, you are up in dollars and down in purchasing power. Both statements are true.
Which one to use when
Use nominal returns when you want to know how many dollars will be in the account. That is the number that appears on your statement.
Use real returns when you want to know what those dollars will buy. That is the number that matters for planning a retirement budget.
The historical stock average of roughly 10% is nominal. The commonly cited 7% figure is that same average after subtracting inflation.
- Real return is approximately nominal return minus inflation.
- Historical stock returns: roughly 10% nominal, roughly 7% real.
- A 4% savings rate against 3% inflation is a 1% real return.
- Goals in today's dollars should be planned with real returns.
- Mixing the two is what makes long-term plans fall short.
The mistake this prevents
Someone projects a portfolio at 8% nominal over thirty years, sees a large ending balance, and plans a retirement budget using today's prices.
That comparison is between future dollars and present prices, which overstates their position substantially. At 3% inflation over thirty years, the overstatement is a factor of about 2.4.
Planning at a real rate of 5% instead produces a smaller balance stated in today's purchasing power, which can be compared directly against today's budget.
Applying it to cash
The same arithmetic applies to savings accounts. A 4.5% APY against 3% inflation is a real return of about 1.5%, which is modestly positive.
A 0.4% account against the same inflation is a real return of about negative 2.6%, which is a genuine loss of purchasing power every year.
Thinking in real terms makes the difference between those two accounts much clearer than comparing the headline rates.
Why wages complicate the picture
Your contributions are unlikely to stay flat over thirty years, because wages have historically risen roughly with inflation over long periods.
A projection assuming a constant $500 a month therefore understates what you will actually invest, which partly offsets the erosion inflation causes on the other side.
You can approximate this by using a blended contribution somewhat above your current amount, or by simply recognizing that the real-terms projection is conservative.
The safest approach is planning in real terms with a flat contribution and treating any wage growth you redirect as upside. That errs in the right direction.
Pick one method and stay with it
Either project in nominal terms and inflate your goal to match, or project in real terms and keep your goal in today's dollars.
Both are correct. The error is starting with one and finishing with the other, which happens easily across a multi-year plan.
Note which method you used alongside your projection so future reviews stay consistent.
For most people, working in today's dollars with a real return is simpler, because your budget and your goals are already expressed that way.
Try these inputs
- Nominal view: $500/mo at 8% for 30 years
- Real view: $500/mo at 5% for 30 years
- Cash comparison: 4.5% savings against 3% inflation