Say the target is $50,000 in five years, starting with $5,000 already saved, at a 4 per cent return. The required contribution is $662.08 a month.
Of the $50,000, you contribute $39,724.61. Your existing savings grow to $6,104.98. Interest across the whole period accounts for $5,275.39.
Over short periods, contributions do the work
Roughly four fifths of that target comes from money you put in. Over five years, at a modest return, compounding has not had long enough to take over. This is the ordinary shape of a short-horizon goal: a house deposit, a car, a wedding.
It has a practical consequence. Chasing a higher return to reach a five-year goal changes a small part of the total while adding real risk to the whole of it. Over five years the market has plenty of time to be down and not much time to recover.
The lever that actually moves the number
The contribution is the largest term and the one you set directly. Time is the second: extending the deadline reduces the monthly figure both because there are more payments and because the earlier ones compound for longer.
Return is third, and it is the one you cannot set, only choose exposure to. It matters enormously over decades, which is why small rate differences over long periods are worth caring about, and much less over a handful of years.
Working backwards is the useful direction
Most goals are set as an amount and a date, which fixes the contribution. If that contribution is not affordable, only three things can give: the amount, the date, or the risk. Naming which one is moving is more honest than quietly assuming a higher return will cover the gap.
The version of this that fails is the one where the target is kept, the contribution is set at what feels manageable, and the shortfall is left to be solved later by performance. That is not a plan; it is a hope with a spreadsheet attached.
Inflation sits underneath all of it
A target set in today's money buys less by the time you reach it. Over five years at a few per cent this is a modest effect, but for goals a decade or more out it is large enough that the nominal target should be set with it in mind. The inflation calculator shows the size of the adjustment.
Run your own figures through the savings goal calculator and note how much of the target comes from contributions rather than growth. That ratio tells you which lever is worth pulling.