Invest Ksh 250,000 at Guaranty Trust Bank for 15 years.
At Guaranty Trust Bank's current weighted-average deposit rate of 8.01%, a Ksh 250,000 deposit grows to about Ksh 827,963 after 15 years — about Ksh 577,963 in interest, assuming monthly compounding and no withdrawals.
Final balance
Ksh 827,963
3.31× your deposit
Deposited
Ksh 250,000
One-off, no withdrawals
Interest earned
Ksh 577,963
At 8.01% p.a.
Year by year
Contributions form the floor; interest compounds on top.
Could you earn more elsewhere?
The same Ksh 250,000 in Cytonn Money Market Fund — currently Kenya's top-yielding MMF at 9.39% net of 15% WHT — would grow to about Ksh 1,016,864 over the same 15 years. Run your own numbers on the compound interest calculator.