Savings Goal Calculator
Tell it what you want to save, what you already have and what you can put aside each month. It works out how many months the goal takes, and how much of the final balance is your own money.
| Savings goal | $ |
| Already saved | $ |
| Monthly deposit | $ / month |
| Annual return | % |
Result
Your result will appear here.
How it works
Each month the balance earns interest and then your deposit is added. Because interest is charged on a slightly larger balance every month, the growth accelerates: the last year of a savings plan usually produces far more interest than the first. That is why the answer is not simply the gap divided by the monthly deposit.
The page solves for time rather than for the balance. It steps month by month until the balance passes the goal, so it handles a zero return, a negative return, or a starting balance that already exceeds the goal without special cases.
Formula
Monthly rate i is the annual rate converted to a monthly equivalent, not divided by twelve, so that twelve months of growth equals the annual figure exactly.
- i = (1 + annual return)1/12 − 1
- Balance after n months = starting balance × (1+i)n + deposit × ((1+i)n − 1) ÷ i
- Months needed = the smallest n where the balance reaches the goal
Worked example
Starting from $5,000 with $400 a month and a 4% annual return, the balance passes $20,000 after 35 months — just under three years. At that point it stands at about $20,414: $14,000 of deposits, and roughly $1,400 of growth on your money.
Assumptions
Returns are assumed to arrive smoothly every month at a constant rate. Real savings accounts, bonds and funds do not behave that way; a 4% average can mean −8% one year and +14% the next. The figure is an average-case planning number, not a promise. Tax on interest, account fees and inflation are all ignored, and deposits are assumed to be made at the end of each month.
Reading the result
Look at the split between what you deposit and what growth contributes. Early in a plan almost all progress comes from deposits; the growth column only becomes meaningful once the balance is large relative to the monthly amount. If the time feels too long, changing the monthly deposit moves the answer far more than chasing a higher return, and it does so without adding risk.
For general information only. Investment returns vary and are not guaranteed.
How to use the Savings Goal Calculator
It takes a few seconds, and every figure is calculated in your browser.
- Enter the savings goal.
- Enter how much you have already saved.
- Enter the monthly deposit.
- Enter the annual return.
- Press Calculate — the result appears in the dark panel beside the form.
- Use Copy, CSV, Share or Print under the result if you want to keep it.
Savings Goal Calculator — frequently asked questions
What formula does the Savings Goal Calculator use?
Monthly rate i is the annual rate converted to a monthly equivalent, not divided by twelve, so that twelve months of growth equals the annual figure exactly. i = (1 + annual return) 1/12 − 1 Balance after n months = starting balance × (1+i) n + deposit × ((1+i) n − 1) ÷ i Months needed = the smallest n where the balance reaches the goal
How does the Savings Goal Calculator work?
Each month the balance earns interest and then your deposit is added. Because interest is charged on a slightly larger balance every month, the growth accelerates: the last year of a savings plan usually produces far more interest than the first. That is why the answer is not simply the gap divided by the monthly deposit. The page solves for time rather than for the balance.
What assumptions and limitations should I know about?
Returns are assumed to arrive smoothly every month at a constant rate. Real savings accounts, bonds and funds do not behave that way; a 4% average can mean −8% one year and +14% the next. The figure is an average-case planning number, not a promise. Tax on interest, account fees and inflation are all ignored, and deposits are assumed to be made at the end of each month.
Can you walk through a worked example?
Starting from $5,000 with $400 a month and a 4% annual return, the balance passes $20,000 after 35 months — just under three years. At that point it stands at about $20,414: $14,000 of deposits, and roughly $1,400 of growth on your money.
Last updated 10 November 2026 · Formula, worked example and assumptions are documented above, and every result is calculated in your browser.