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Savings Goal Calculator

Work out the deposit needed each month, quarter or year to reach a savings target by your chosen date, verified by re-running the forward calculation.

UniversalDeterministic arithmeticClass A · deterministic arithmeticNo statutory rules requiredMethodology
AUD
AUD

Enter a target, rate and timeframe to find the deposit needed.

Summary

Enter a rate and timeframe to see the working behind the projection.

Working

  1. i = annual rate ÷ periods per year (12 monthly, 4 quarterly, 1 annually)
  2. each period: interest = balance × i, then balance = balance + deposit
  3. interest is rounded half-up to the cent as it is credited
  4. closed form: FV = P × (1 + i)ⁿ + C × ((1 + i)ⁿ − 1) ÷ i, with an extra (1 + i) factor for start-of-period deposits
  5. the simulation and the closed form are compared every time; a mismatch beyond per-period rounding is a failure, not a warning

Assumptions

  • The rate is constant for the whole projection and interest is credited on the stated cycle.
  • Deposits are made in full every period, and nothing is withdrawn.
  • Tax on interest, account fees and inflation are excluded from the nominal figures.

Limitations

  • A projection over many years is an arithmetic illustration, not a prediction: real returns vary and can be negative.
  • Variable-rate accounts, introductory bonus rates and conditions attached to bonus interest are not modelled.
  • No product, provider or rate is being offered or compared here.
  • Result accuracy class A: deterministic arithmetic on the figures you enter.

Common questions

How is the required deposit worked out?

The calculator solves the future-value annuity relationship for the one unknown, the deposit per period, given your target amount, opening balance, rate, term and deposit timing. The solved deposit, rounded up to the cent, is then run through the full period-by-period projection forward, and every figure shown is read from that forward run rather than from the solve, so the deposit and the projected outcome can never disagree.

Does it matter whether deposits go in at the start or end of each period?

Yes, slightly. A deposit made at the start of a period earns interest in that same period, so the required deposit is a little lower than with end-of-period timing. The timing option controls which convention the solve uses, and the assumptions shown with the result state the setting in force.

What happens if the opening balance already grows past the target?

The required deposit is floored at zero. If the opening balance compounding on its own reaches the target by the chosen date, the calculator reports that no further deposits are needed under the entered rate rather than producing a negative deposit.

Why is the monthly deposit not exactly a third of the quarterly one?

Deposits are modelled at the same frequency as compounding, so monthly deposits mean twelve smaller amounts a year, each earning interest from the month it arrives, while quarterly means four larger ones arriving later on average. Earlier money compounds for longer, so the frequencies are not simple multiples of each other. The per-period figure reported is exact for the frequency selected.

Is reaching the savings target guaranteed?

No. The solve holds the entered rate constant for the whole term and models no fees, tax or missed deposits. Real savings rates change and market returns vary, so the result is general information about the arithmetic of your inputs, not a prediction. Every assumption used is listed beside the result.

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