Savings Goal Calculator
Tell it the target, what you've saved, and when you need it — the required monthly deposit updates as you type, and the link in your address bar always reflects your numbers.
How this calculator works
The tool works backwards from your target. First it grows your current savings forward at the rate you chose (compounded monthly), then it finds the fixed month-end deposit whose accumulated value covers the rest: C = (G − P·(1 + i)n)·i / ((1 + i)n − 1), where G is the goal, P your current balance, i the monthly rate, and n the number of months. If your existing savings would grow past the goal on their own, the answer is simply $0. Rates on real accounts change over time, so revisit the number when yours does.
Worked example
Target $20,000 in 3 years, starting from $2,000 at 4%. Your $2,000 grows to about $2,254.54 on its own, leaving roughly $17,745 for deposits and their interest to cover. The required deposit works out to $464.77 a month. Over 36 months you'll deposit about $16,731.54, and interest contributes the remaining $1,268.46. Give yourself 5 years instead and the monthly figure drops to about $264.83.
Frequently asked questions
What interest rate should I assume for a savings account?
It depends on where the money sits. High-yield savings accounts have recently paid noticeably more than traditional big-bank accounts, but rates move with the market and vary between banks, so check current offers rather than assuming a fixed number. The default here (4%) is just a placeholder — swap in whatever your account actually pays.
What happens if I miss a month?
Nothing breaks — you just arrive slightly short or slightly late. One missed $465 deposit in a 3-year plan leaves you roughly that amount (plus its lost interest) behind. The easy fixes: extend the deadline by a month, or nudge the remaining deposits up a little. Re-run the calculator with your new balance and remaining time to get the updated number.
Why does adding more time shrink the monthly amount so much?
Two effects stack: the target is split across more deposits, and every deposit has longer to earn interest. Saving toward $20,000 from $2,000 at 4% takes about $464.77 a month over 3 years, but only about $264.83 a month over 5 years — a 43% smaller deposit for 67% more time.
Should the money be in savings or invested?
The classic factual framing is timeline: money needed within a few years is usually kept somewhere stable and accessible, because markets can drop right when you need to withdraw, while longer horizons give volatile assets time to recover. What's right for you depends on your situation — this calculator does the arithmetic for whatever rate you choose, and isn't financial advice.