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Simple Interest Calculator Kenya — See Your Exact Return

Enter your principal, annual interest rate, and time period to calculate your return on fixed deposits, Treasury Bills, savings accounts, and other simple-interest products in Kenya.

Simple interest in Kenya is calculated as Principal × Rate × Time. Most Kenyan fixed deposits, Treasury Bills, and short-term bank products use simple interest — meaning you earn interest only on your original deposit, not on accumulated interest. For example, KES 100,000 at 10% for 1 year earns KES 10,000. Interest income is subject to 15% withholding tax (WHT), making the net return KES 8,500 — including Treasury Bills. Only infrastructure bonds are tax-exempt. Use the calculator below to see your exact return.
Calculator 01
How Your Money Grows
If I put money somewhere that pays a flat rate, how much interest will I earn?
Amt
Total interest earned
18,800
Your starting amount
100,000
Final value
118,800
In plain English

100,000 at 9.4% for 2 years earns 18,800 in simple interest. Your total would be 118,800.

Simple Interest Formula — How It Works

I = P × R × T
P
Principal
R
Annual Rate
T
Time (years)

Example: You invest KES 100,000 in a Kenyan fixed deposit at 12% per annum for 2 years. Your simple interest is 100,000 × 0.12 × 2 = KES 24,000. After 15% withholding tax (KES 3,600), your net interest is KES 20,400 and your total value is KES 120,400.

Unlike compound interest, simple interest does not reinvest earnings. This makes it easier to predict but produces lower returns over long periods. Most Kenyan fixed deposits and Treasury Bills use simple interest.

Where to Earn Simple Interest in Kenya — 2026 Rates

Compare the products that use simple interest. Rates updated daily on Serrari.

ProductTypical RateMin. InvestmentTax on InterestTenure
Treasury Bills9 – 12%KES 100,00015% WHT91 – 364 days
Fixed Deposits (KES)8 – 13%KES 1,000+15% WHT1 – 12 months
Treasury Bonds12 – 16% YTMKES 50,00015% WHT (≤ 10 yrs) / 10% (> 10 yrs)2 – 25 years
Savings Accounts6 – 14%KES 015% WHTInstant access
Fixed Deposits (USD)3 – 5.5%USD 1,000+15% WHT3 – 12 months

Simple Interest vs Compound Interest — Kenya Comparison

Understanding the difference helps you choose the right product for your goals.

FactorSimple InterestCompound Interest
FormulaP × R × TP(1 + r/n)ⁿᵗ
Interest earned onOriginal principal onlyPrincipal + accumulated interest
KES 100K at 10% for 5 yearsKES 50,000 interestKES 61,051 interest
Kenya productsFDs, T-Bills, BondsMMFs, Unit Trusts, SACCOs
Best forShort-term, predictable returnsLong-term wealth building

Want to see compound interest in action? Try the Compound Interest Calculator

Simple Interest Calculator — FAQ

Simple interest is calculated as Principal × Rate × Time. Unlike compound interest, you only earn interest on the original amount deposited — the interest itself does not earn further interest. Most Kenyan fixed deposits, Treasury Bills, and short-term bank products use simple interest.

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Serrari Markets provides independent financial data and educational tools. Serrari Limited is a financial data, education and investment-origination platform. Serrari is not a fund manager, investment bank or deposit-taking institution and does not hold client investment funds. Where clients elect to invest, transactions are executed through appropriately licensed and regulated third-party financial institutions. The relevant product provider remains responsible for the issuance, management and custody of each investment. Calculator results are estimates for educational purposes. Always consult a licensed advisor before making investment decisions.