Savings Calculator
Project your savings balance and find out when you will hit your goal.
How the calculator works
The projection compounds monthly: the balance grows by one twelfth of the annual rate each month, then the month's deposit is added at month-end. Repeating that loop for every month of the horizon gives the final balance exactly, and the same loop tracked year by year feeds the growth table. When a goal is set, the calculator inverts the growth formula to solve for the number of months needed; if the goal is already met the result says so, and if the current plan cannot reach the goal within the entered period the result row says that plainly instead of guessing. Because deposits are modeled at month-end, balances are slightly conservative compared with depositing at the start of each month.
Formula
Months to goal = ln((G × i + D) ÷ (P × i + D)) ÷ ln(1 + i)
Where:
- P — the initial deposit
- D — the monthly deposit
- i — the monthly rate (annual rate ÷ 12 ÷ 100)
- n — the number of months
- G — the savings goal
Example
Start with $1,000, add $100 every month, and earn 5% a year: after 10 years the balance is about $17,175.24 — $13,000 deposited and $4,175.24 from interest. Set a $20,000 goal with the same plan and the calculator reports roughly 136 months — about 11 years and 4 months — and shows the calendar date the goal lands on. Raising the monthly deposit to $150 pulls that date in by more than two years, showing why the monthly habit matters more than the starting amount.