Nominal vs real return
The nominal return is the rate you see. The real return is the growth in purchasing power after tax and inflation:
Real return = (1 + net rate) ÷ (1 + inflation) − 1
The net rate is the rate minus tax. Example: 5% with 20% tax becomes 4% net. With 3% inflation the real return is only about 0.97% a year.
The break-even rate
To avoid losing purchasing power, the pre-tax rate must be at least inflation ÷ (1 − tax). With 3% inflation and 20% tax that is 3.75%.
Why show the final value twice?
The nominal value is the rupiah amount in the future. The value in today's rupiah shows real purchasing power, because Rp100 million in ten years does not buy what Rp100 million buys now.
Frequently asked questions
Can savings interest lose to inflation?
Yes. Ordinary savings accounts often pay under 2% before tax, below inflation, so purchasing power falls even while the balance rises.
How is deposit interest taxed?
Deposit and savings interest carries a 20% final tax (deposit interest up to a threshold may be exempt). Enter 0 for untaxed instruments such as money market funds.
What inflation should I use?
Indonesian inflation averaged about 3% over the last 10 years. For long-term planning 3–4% is a reasonable assumption.
Is the result guaranteed?
No. Rates and inflation change over time; this is a simulation with fixed numbers.
Results are simulations to help planning and may differ from official calculations by agencies, employers or banks. Last updated 2026-11-04.