Nominal Return vs Real Return: What Inflation Actually Takes From Your Portfolio
4 min read
Loading...
4 min read
Your portfolio statement says this year's return came out to a healthy 12%. That looks like real progress, until you remember that prices in Indonesia kept rising the whole time you were earning it. Inflation never sends you a bill. It just quietly reduces what a rupiah of return can actually buy, and by the time you notice, part of that 12% is already gone. The gap between what your nominal return shows and what your real return actually is comes down to one formula, and most portfolio trackers, NetWort included, only display the first number unless you work out the second one yourself.
Nominal return is the percentage gain your portfolio shows before anything else is subtracted: today's value against your cost basis, expressed as a percentage. It is the number every brokerage app and portfolio tracker leads with.
Real return is what that percentage is worth after inflation, the rate at which prices for everything else are rising, has been taken out. If your portfolio grew 12% in nominal terms while prices rose roughly 3% over the same period, you did not get exactly 3 percentage points poorer in real terms. The two rates interact multiplicatively, not by simple subtraction, and that difference is bigger than it looks once the numbers involved get larger.
As of the most recent official release, Indonesia's headline inflation (year on year) stood at 2.88% in July 2026, down from 3.34% in June, and still inside Bank Indonesia's 1.5% to 3.5% target band. Source: BPS (Statistics Indonesia), as reported by Indonesia-Investments and Databoks, retrieved 29 August 2026. BPS had not yet published an August 2026 print at the time of writing, so July's figure is the most current one available.
You can track this number alongside the BI Rate and the rupiah exchange rate on NetWort's Macro Context page, since all three move independently and each one changes what your real return actually is this month.
Real return = (1 + Nominal return) ÷ (1 + Inflation rate) − 1
A common shortcut is to just subtract inflation from nominal return. That shortcut is close enough when both numbers are small, but it quietly overstates your real return, and the size of the overstatement grows as either number gets bigger.
Using July's 2.88% inflation rate:
| Nominal return | Inflation | Simple subtraction | Fisher equation (exact) | Gap |
|---|---|---|---|---|
| 12% | 2.88% | 9.12% | 8.86% | 0.26 pts |
| 40% | 2.88% | 37.12% | 36.08% | 1.04 pts |
At a modest 12% nominal return, the shortcut is off by about a quarter of a percentage point, small enough that it rarely changes a decision. At 40%, roughly what a strong crypto-heavy year can produce, the shortcut overstates your real return by a full percentage point. The shortcut is not wrong so much as it is an approximation that gets worse exactly when the stakes are highest.
A gap this small on one year's return looks trivial, but real return compounds the same way nominal return does. Overstate it by even half a point every year for a decade, and the gap between what you assumed you were on track for and what you actually have grows into real rupiah, not rounding error. That matters most for anyone using a return assumption to plan how much a portfolio can support later, the same real-vs-nominal question that sits underneath Indonesia's version of the 4% retirement withdrawal rule.
Pull your own nominal return from the Portfolio Health view on your NetWort dashboard, plug it into the formula above with this month's inflation rate from the Macro Context page, and you will have the number that actually matters: not what your portfolio says it earned, but what that return can actually buy.