Savings Goal Calculator

How the required monthly contribution is worked out

The calculator does two things in sequence. First, it takes whatever you already have saved and compounds it forward, at the annual return you enter, to see what that lump sum alone becomes by your target date — with no further contributions. Second, it compares that grown amount to your target and, if there's a gap, solves for the level monthly contribution that would close it, compounding alongside the lump sum at the same assumed rate.

That second step uses an annuity factor — the standard way to answer "what fixed payment, made every month and compounding at rate r, adds up to a given amount after n months?" It's the same building block used behind the Down Payment and Retirement Savings calculators, just solved for the payment instead of the end value.

A real reference point for your rate assumption

This calculator deliberately doesn't default to a quoted savings or money-market product rate — those vary by provider and change often. What does exist publicly is the return the Kenyan government pays on its own short-term borrowing, set at weekly Treasury bill auctions. It isn't what a bank savings account or unit trust will pay you, but it's a genuine, sourced data point for what a low-risk shilling return looks like right now.

Source: Central Bank of Kenya — Treasury bill auction results, as of 16 July 2026. Reference only — not the rate this calculator assumes, and not a savings product return.

Worked example: KES 1,000,000 in 3 years, starting from KES 100,000

These are the calculator's own defaults. Left untouched, the KES 100,000 already saved compounds forward monthly at 10% a year — over 36 months, that alone grows to about KES 134,818, without a single further deposit. That leaves a shortfall of about KES 865,182 against the KES 1,000,000 target. Running the annuity factor over that shortfall and the same 36-month, 10% assumption gives a required monthly contribution of about KES 20,707. Put together — the starting lump sum, 36 contributions of KES 20,707, and growth on both — the projection lands almost exactly on KES 1,000,000.

Why the rate you enter changes the answer more than you'd think

Because the shortfall compounds over the full period, a higher assumed return doesn't just add a little to the projection — it reduces the monthly contribution needed to reach the same target, and the effect grows with the number of years involved. That cuts both ways: an optimistic rate understates what you actually need to save each month. Enter the return you're genuinely earning, or a conservative planning assumption, rather than the most attractive figure you've seen quoted.