Investment Calculator
Calculate investment returns with compound interest. Monthly contributions, inflation adjustment and scenario comparison.
Disclaimer: This tool is for informational purposes only and does not constitute professional accounting, legal or financial advice. Results are estimates; consult a certified advisor for important decisions. Terms of Service.
How Investment Returns Are Calculated
Compound interest with contributions: A = P × (1 + r/n)^(n×t) + PMT × [((1 + r/n)^(n×t) - 1) / (r/n)]
Rule of 72
Quick doubling estimate: 72 / Annual Return (%). At 30% annual return, money doubles in ~2.4 years.
Why Inflation Adjustment Matters
Nominal returns mislead. A 40% return with 50% inflation is a realloss of -7%. The tool adjusts for your inflation estimate to show true purchasing power.
How to Use This Tool
- Enter starting capital
- Enter monthly contribution (optional)
- Set annual return and duration
- Add inflation rate — see real returns
- Compare low/medium/high scenarios
Typical Returns by Asset
- TL Deposits: 30-45% gross (lower after withholding tax)
- Gold: Variable, inflation hedge
- USD/EUR: Currency appreciation + interest
- Stocks (BIST): 35-60% long-term average
- Mutual Funds: 20-80% by fund type
Example: The Power of Regular Investing
Investing 5,000 TL every month at 40% annual compound return for 10 years means 600,000 TL of contributions — yet compounding can grow the balance to over 4.5 million TL. The engine is "interest on interest": small early gains eventually exceed the principal itself. But this is nominal — with 35% inflation, the real return is far lower (see below).
Common Mistakes
- Mistaking nominal for real return: A 40% return with 35% inflation is only ~3.7% real. Look at the actual gain in purchasing power.
- Forgetting tax and withholding: Withholding on deposit interest and capital-gains tax on some assets reduce net returns.
- Underestimating starting early: Time is the biggest variable in compounding; starting 5 years earlier can beat doubling the monthly amount.