NumberTally Savings Calculator
See how your savings grow with compound interest and regular monthly deposits. Enter your starting balance, monthly contribution, expected return, and time horizon — or set a goal and find out exactly how much you need to save each month to reach it.
Advanced options
Set a goal to compute the monthly deposit needed to reach it — and how long your current plan takes to get there.
How savings growth works
Your balance grows from two forces at once: the interest earned on money already saved, and the new deposits you add. Because interest compounds monthly, money you deposit early does far more work than money deposited late — the first year's deposits earn interest for the entire remaining term.
This calculator compounds monthly and assumes deposits are made at the end of each month. Real savings accounts compound daily or monthly and rates change over time, so treat the projection as a planning estimate, not a guarantee.
Reaching a goal
When you set a savings goal, the calculator works the future-value formula backwards: it subtracts what your initial deposit will grow to on its own, then solves for the monthly deposit that covers the remaining gap. If your initial deposit alone already reaches the goal, the required monthly deposit is $0.
The teal box answers the flip side: keeping your current monthly deposit, how many years and months until you get there — and the calendar month you\u2019ll arrive.Frequently Asked Questions
Is it better to save more now or the same amount every month?
Saving more now almost always wins, because early money compounds the longest. A $10,000 lump sum at 6% for 20 years grows to about $33,100 on its own — matching that with monthly deposits alone would take roughly $72/month for the full 20 years.
What interest rate should I assume?
High-yield savings accounts have recently paid 4–5%, while a diversified stock portfolio has historically returned about 7–10% per year before inflation. Use a conservative rate for money you cannot afford to lose.
Does this account for inflation?
No — the projected balance is in nominal dollars. At 3% annual inflation, $100,000 in 20 years buys what about $55,400 buys today. Use our Future Value Calculator to see the inflation-adjusted figure.
Are deposits assumed at the beginning or end of the month?
End of the month (ordinary annuity). Beginning-of-month deposits would earn slightly more — roughly one extra month of interest on each deposit.
Why does the yearly table differ slightly from my bank statement?
Banks may compound daily, credit interest on different dates, or change rates mid-year. This calculator uses a fixed annual rate compounded monthly for the whole term.