Savings Goal Calculator
Target, deposit, rate — the months and the date you get there.
How this is calculated
Solve for n: target = start×(1+r)ⁿ + deposit×((1+r)ⁿ − 1)⁄r r = rate ÷ 12
Worked example: R100,000 target at R2,000/month and 8% from zero takes 44 months — 3 years 8 months — with R88,000 deposited and the rest earned. At 0% the same goal takes 50 months; the interest quietly removes half a year of saving.
Three levers, and only two are yours
A savings goal has four quantities — target, monthly contribution, time and return — and fixing any three determines the fourth. What people usually want is a monthly figure, which means accepting a target, a deadline and a rate. Of those, the return is the one you least control: it is set by markets and by how much risk is appropriate for the timeframe. The contribution and the deadline are yours, and they are where the arithmetic should give.
If the required monthly figure comes out uncomfortable, the honest responses are to extend the deadline or reduce the target, not to assume a higher return. Solving a savings shortfall by raising the assumed rate is how people end up in unsuitable investments.
Match the risk to the horizon
Money needed within a year or two belongs somewhere it cannot fall: a fixed deposit or a money-market account. Money for five to ten years can take moderate risk. Money for twenty years or more can take substantially more, because there is time to recover from a bad sequence and inflation is the larger threat over that horizon. Putting a house deposit needed next year into equities is the most common version of this mistake, and it is discovered at exactly the wrong moment.
Contribute first, then spend
The behavioural evidence here is unusually consistent: a debit order that moves money on payday outperforms an intention to save whatever remains at month end, because whatever remains is reliably close to nothing. Escalating the amount alongside pay rises captures increases before lifestyle absorbs them, which is the least painful way to raise a savings rate.
Inflation, and what your target will actually buy
A target set in today's money will not buy today's basket when you reach it. R500,000 for a deposit in ten years, with property inflation at 5%, needs to be closer to R815,000 to buy the same house. Either set the goal in future money or accept that the shortfall will need covering. This is the correction most people skip, and it is the one that decides whether the plan works.
Frequently asked questions
How does the savings goal calculator work?
It solves the future-value equation for time: given your target, monthly deposit, any starting balance, and an annual rate compounded monthly, it finds how many months until the balance crosses the target — then shows the date that lands on.
What interest rate should I enter?
The rate your money will actually earn: a savings-account or money-market rate (currently mid-single digits in most countries, higher in South Africa) for cash goals, or a conservative long-run estimate if the goal is invested. When unsure, use a lower rate — arriving early beats planning on returns that never came.
Why does starting earlier matter more than saving more?
Because the earliest deposits compound the longest. In the worked example below, doubling the deposit reaches the goal in roughly half the time — but starting a year earlier with the same deposit also removes months, for free. The calculator makes both effects visible instantly.
What if the goal shows as unreachable?
With no deposits and no interest, no future month ever crosses the target, so the calculator says so honestly instead of inventing a number. Add a monthly amount — even a small one moves the date from "never" to "counted".