Sources
- CSGB / Asgari Ücret Tespit Komisyonu (2026 brüt/net)
- GİB gelir vergisi tarifesi 2026
- EPDK mesken elektrik kademeli tarife (yaklaşık)
- BOTAŞ / dağıtım şirketleri doğalgaz (yaklaşık)
- Hazine ve Maliye — kıdem tazminatı tavanı 1. dönem 2026
Compound Interest Guide
Model returns earning further returns over successive periods and separate net real outcomes.
Future-value formula
Principal is multiplied by one plus periodic rate raised to the number of periods. Prior earnings become part of the next interest base, unlike simple interest on principal only.
Frequency and effective rate
A nominal annual rate must match monthly or other periods. Effective annual return reflects compounding rather than multiplying the nominal rate by twelve.
Contributions and timing
Beginning-period contributions earn for longer than ending contributions. Enter contribution amount and timing separately instead of folding everything into one starting principal.
Tax, fees and inflation
Deduct tax and fees, then compare with inflation for purchasing power. High nominal rates can still be weak in real terms.
Compare with simple interest
On equal assumptions, compounding overtakes simple interest as time lengthens. Read product sheets to see which convention is advertised.
Scenario discipline
Run low, mid and high rate cases. The tool is educational and does not guarantee returns.
Early withdrawal assumptions
Some deposits penalise early withdrawals. Compounding models usually assume money stays invested. Run a separate liquidity scenario if you may need cash mid-term.
Nominal rate versus APY language
Marketing may quote nominal or effective figures. Match the calculator frequency to the figure type you paste in, or convert first so comparisons stay honest.
Practical tips
- Match rate period to compounding frequency.
- Specify contribution timing.
- Net out tax and fees.
- Adjust for inflation.
- Use a three-rate scenario range.
- Model early-withdrawal penalties separately.
- Match nominal versus effective rate labels.
FAQ
How does it differ from simple interest?
Previously earned interest also earns returns in later periods.
Does timing of deposits matter?
Yes. Earlier contributions compound longer.
Is nominal return the same as real return?
No. Inflation and costs can erase purchasing power.
Is the result a guarantee?
No. It is a scenario for learning and planning.
Which frequency should I choose?
The one closest to the product’s actual interest schedule.
What if I withdraw early?
Product rules may cut the rate or apply a penalty; the plain formula does not include that automatically.
Is APY the same as nominal rate?
Not always. Convert or match frequency before comparing products.