Transparent method
The formula
Worked example
Example inputs
How to interpret the result
The months required to reach a savings goal shrinks faster than a proportional amount when the deposit amount increases, because a larger deposit also means more money compounding for a longer remaining stretch of the timeline. The relationship between deposit size and time saved isn't a straight line.
Before you rely on it
What to check
Test the projected timeline at a couple of different deposit amounts to see how much time an increase actually saves, rather than assuming the relationship is proportional.
The common error
Where people go wrong with time to save calculator
Assuming doubling the monthly deposit simply halves the time needed to reach a goal. Because growth compounds on a larger balance sooner, a bigger deposit often shortens the timeline by more than a simple proportional guess would suggest.
Sensitivity evidence
How annual return changes the time to goal
| Annual return | Time to goal | Total contributions |
|---|---|---|
| 2.0% | 51.0 months | $48,250 |
| 3.0% | 49.0 months | $46,750 |
| 4.0%worked example | 48.0 months | $46,000 |
| 5.0% | 46.0 months | $44,500 |
| 6.0% | 45.0 months | $43,750 |
Every input, tested
Which input moves the time to goal most
| Input | Tested from | To | Time to goal at each end | Swing |
|---|---|---|---|---|
| Savings goal | $45,000 | $55,000 | 42.0 months to 53.0 months | 11.0 months (23%) |
| Monthly deposit | $675 | $825 | 52.0 months to 44.0 months | 8.0 months (17%) |
| Current savings | $9,000 | $11,000 | 49.0 months to 46.0 months | 3.0 months (6.3%) |
| Annual return | 3.0% | 5.0% | 49.0 months to 46.0 months | 3.0 months (6.3%) |
Two variables at once
Time to goal by annual return and savings goal
| Annual return \ Savings goal | $40,000 | $50,000 | $60,000 |
|---|---|---|---|
| 2.0% | 38.0 months | 51.0 months | 62.0 months |
| 3.0% | 37.0 months | 49.0 months | 60.0 months |
| 4.0% | 37.0 months | 48.0 months | 58.0 months |
| 5.0% | 36.0 months | 46.0 months | 57.0 months |
| 6.0% | 35.0 months | 45.0 months | 55.0 months |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Savings goal | $50,000 |
| Current savings | $10,000 |
| Monthly deposit | $750 |
| Annual return | 4.0% |
| Time to goal | 48.0 months |
| Total contributions | $46,000 |
Where the inputs come from
Savings goal is the amount you want, current savings is what you have, monthly deposit is what you can add reliably, and annual return is the rate the account pays. Be honest about the deposit, since the biggest driver of the timeline is how much you actually save rather than the rate. If the goal is in the future, add expected price increases to the target.
When the result stops applying
It assumes a constant return and deposit, ignoring taxes and changing income. Interest at savings rates adds little, so the timeline is close to the goal gap divided by the deposit. Prices for the thing you are saving for may rise while you save, moving the finish line. Irregular deposits, such as bonuses, are not modeled.
What to compare it with
Work backward from a deadline with the savings goal calculator, and see the required interest rate page if you have a fixed deposit and a fixed date. The emergency fund and down payment calculators give common targets. The millionaire calculator uses the same idea for a long-term investment balance.
People also ask
Frequently asked questions
What is the fastest way to shorten the timeline?
Raise the monthly deposit. At savings-account rates, adding money changes the finish date far more than finding a slightly higher rate.
Does interest matter for a short goal?
Only a little. On a three-year goal at 4%, interest may add a few percent of the total, so the deposit does most of the work.
What if my goal price rises while I save?
Update the goal periodically, or set it higher from the start using an inflation estimate, so you are not surprised at the end.