Compound Interest Calculator (TZS)

Compound interest — the eighth wonder

Albert Einstein supposedly called compound interest "the eighth wonder of the world." For Tanzanian savers it's the single most important concept to understand: small monthly deposits, compounded over decades, become large balances. The maths is unforgiving — start late and you can't catch up easily.

Tanzanian deposit rates as benchmarks

• Bank fixed deposits: typically 7–10% per year for 12-month TZS deposits at CRDB, NMB, NBC, Equity.
• Treasury bills: 10–13% — government short-term paper, the safest instrument.
• Treasury bonds: 13–16% over 5–25 years — locked in but compounds beautifully.
• SACCO / VICOBA: variable; check fees and reliability.
• Money-market unit trusts: 8–12% — UTT-AMIS, Watumishi.

The 72 rule (mental math)

Divide 72 by the interest rate — that's roughly how many years it takes your money to double. At 9%, you double in 8 years. At 12%, in 6 years. At 6%, in 12 years. Tanzania's inflation has averaged 4–6%, so a 9% deposit is a real positive return.

Goal: 1 million TZS at retirement

• Save TZS 5,000/month at 9% for 40 years → ≈ TZS 23 million.
• Save TZS 50,000/month at 9% for 30 years → ≈ TZS 91 million.
• Save TZS 200,000/month at 9% for 20 years → ≈ TZS 134 million.

Pair with the NSSF Pension Projection, the Loan Calculator, and the ROI Calculator.