What this calculator does
Most savings advice starts with a target and stops there. The useful question is what the target costs per month, given the time available and what the money earns while it waits. This calculator answers that directly, and separates the part you contribute from the part interest contributes.
The relationship between time and monthly cost is not linear. Doubling the timeframe more than halves the required contribution, because your existing balance and every contribution have longer to earn. If the monthly figure looks impossible, adding a year is usually a bigger lever than chasing a higher return.
The formula
The amount you already have is grown forward to the target date first. Whatever gap remains must be filled by contributions, so the annuity formula is rearranged to solve for the payment that exactly closes it.
| Term | Meaning |
|---|---|
| FV | The target amount you want at the end. |
| P | What you have saved already. |
| i | Monthly return: annual return ÷ 12 ÷ 100. |
| N | Number of months until the target date. |
The inputs explained
| Field | What to enter |
|---|---|
| Target amount ($) | The amount you want to have at the end. |
| Already saved ($) | Money already set aside for this goal. Enter zero if starting fresh. |
| Annual return (%) | The annual return the savings earn while you accumulate. Use a conservative figure for short goals: cash rates rather than share market returns. |
| Years to save | Years until you need the money. Half years are accepted. |
When to use it
Saving a house deposit
Enter the deposit you need, what you have, and the years you are giving yourself. Because deposits are typically needed within a few years, use a cash or term deposit rate rather than an optimistic investment return: the money cannot afford to fall in value just before you need it.
Building an emergency fund
Target three to six months of expenses. Since this money needs to stay accessible, the return will be modest, and the monthly contribution is doing nearly all of the work.
Planning for a known future expense
A wedding, a car replacement, a large trip. Enter the date and the amount, and the required monthly figure tells you whether the plan is realistic or whether the target or timeline needs adjusting.
Testing whether a timeline is realistic
If the monthly figure exceeds what you can commit, try extending the term by a year and re-running. The drop in required contribution is often larger than people expect.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Saving $50,000: what it costs per month
The same target over different timeframes, with $5,000 already banked and a 4% return.
| Time available | Save each month | Total you contribute | Interest earned |
|---|---|---|---|
| 1 year | $3,665.08 | $43,980.95 | $1,019.05 |
| 2 years | $1,787.45 | $42,898.92 | $2,101.08 |
| 3 years | $1,161.91 | $41,828.86 | $3,171.14 |
| 5 years | $662.08 | $39,724.61 | $5,275.39 |
| 7 years | $448.43 | $37,668.09 | $7,331.91 |
| 10 years | $288.94 | $34,672.37 | $10,327.63 |
How the return rate changes a five-year plan
Rate matters, but over a five-year horizon it is a secondary lever compared with time.
| Annual return | Save each month | Total you contribute | Interest earned |
|---|---|---|---|
| 0% | $750.00 | $45,000.00 | $0.00 |
| 2% | $705.42 | $42,324.95 | $2,675.05 |
| 4% | $662.08 | $39,724.61 | $5,275.39 |
| 6% | $619.98 | $37,198.56 | $7,801.44 |
| 8% | $579.10 | $34,746.26 | $10,253.74 |
| 10% | $539.45 | $32,367.02 | $12,632.98 |
Different targets on a three-year timeline
Starting from nothing, with three years and a 4% return.
| Target | Save each month | Total you contribute | Interest earned |
|---|---|---|---|
| $10,000 | $261.91 | $9,428.63 | $571.37 |
| $25,000 | $654.77 | $23,571.59 | $1,428.41 |
| $50,000 | $1,309.53 | $47,143.17 | $2,856.83 |
| $100,000 | $2,619.07 | $94,286.35 | $5,713.65 |
| $200,000 | $5,238.13 | $188,572.69 | $11,427.31 |
Questions
What return should I assume for a savings goal?
It depends on the timeframe. For goals within about three years, use a savings account or term deposit rate, because you cannot risk a fall in value. For longer goals, a diversified investment return may be appropriate, but it also introduces the risk of arriving short.
What if the required amount is more than I can save?
Three levers: extend the timeline, lower the target, or increase the starting balance. Extending the timeline is usually the most effective, since it gives compounding room to work.
Does the calculator assume I save at the start or end of each month?
At the end of each month. Saving at the start would earn one extra month of interest per contribution, a small difference that grows slightly on long terms.
Should I include the interest as part of my savings rate?
No: the monthly figure it returns is your own contribution only. The interest earned line shows what the account adds on top.
To project growth from a fixed contribution instead, use the compound interest calculator. For retirement-length horizons, see the retirement projection.