Compound Interest Calculator: See How Your Savings Grow
Enter a starting amount, a monthly top-up, an interest rate and a number of years to see how your money grows when your interest starts earning interest too.
Rates checked 9 Nov 2026 against official sources (listed below).
Balance after 10 years
KES 1,159,577
You put in
KES 650,000
Earnings (after tax)
KES 509,577
| Year | Balance |
|---|---|
| Year 1 | KES 118,063 |
| Year 2 | KES 193,254 |
| Year 3 | KES 276,318 |
| Year 4 | KES 368,080 |
| Year 5 | KES 469,451 |
| Year 6 | KES 581,436 |
| Year 7 | KES 705,148 |
| Year 8 | KES 841,814 |
| Year 9 | KES 992,791 |
| Year 10 | KES 1,159,577 |
Interest is compounded monthly and top-ups are added at the end of each month. No tax is deducted; if your savings product withholds tax on interest (for example 15% on money market funds in Kenya), use the money market fund calculator instead.
About this calculator
It works in any currency: the figures show in shillings, but the maths is the same for naira, cedis or rand.
Why compounding matters
With simple interest you earn only on what you put in. With compound interest, each month's interest is added to the balance and starts earning too. Over long periods, the difference is large: KES 5,000 a month at 10% for 10 years grows to about KES 1.16 million from KES 650,000 of your own money (including the KES 50,000 you start with).
How much KES 5,000 a month grows to
Saving KES 5,000 a month from zero, with interest added monthly and before tax:
| Years | You put in | At 8% a year | At 10% a year | At 12% a year |
|---|---|---|---|---|
| 5 | KES 300,000 | KES 367,384 | KES 387,185 | KES 408,348 |
| 10 | KES 600,000 | KES 914,730 | KES 1,024,225 | KES 1,150,193 |
| 20 | KES 1,200,000 | KES 2,945,102 | KES 3,796,844 | KES 4,946,277 |
Time does most of the work. At 10%, the first ten years add about KES 424,000 of interest. The next ten add more than KES 2 million, because by then the interest is earning interest on a much bigger balance.
Where you can earn compound interest
- Money market funds add interest daily and let you top up any time. See the best money market funds in Kenya and in Nigeria.
- Treasury bills pay a fixed rate for a fixed term. Reinvest the interest each time a bill matures to get the compounding effect; our guide to buying Treasury bills in Kenya explains how.
- SACCOs pay interest on deposits and dividends on shares once a year. Leaving dividends in your account lets them compound; compare the best SACCOs in Kenya.
- Savings apps such as M-Shwari Lock Savings and KCB M-Pesa pay interest on locked savings; see the best savings apps in Kenya.
Getting realistic results
- Use a realistic rate. Rates change. Check the current rate on the product you plan to use, and try a lower rate too, to see a cautious result.
- Allow for tax. In Kenya, 15% withholding tax comes off interest from money market funds and Treasury bills before it reaches you. Use the tax box above to include it.
- Allow for inflation. A balance that looks large in 20 years will buy less than it would today.
- Avoid "guaranteed" high returns. Anyone promising 20% or more a month, rather than a yearly rate that moves with the market, is running a scheme, not an investment.
Frequently asked questions
What is compound interest?
Interest calculated on your deposits plus the interest already earned, so your balance grows faster the longer you leave it.
How often is interest compounded?
It depends on the product. Money market funds usually accrue daily, bank fixed deposits often monthly or at maturity, and SACCOs pay dividends once a year.
Does this include tax?
Only if you enter a tax rate. Many savings products deduct tax on interest, which lowers the final balance.
How long does it take to double my money?
A quick rule: divide 72 by the yearly interest rate. At 10% a year, money left untouched roughly doubles in about seven years. At 12%, about six.
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