Savings goal calculator

Enter a target amount, what you already have and what you can save each month to see how long the goal takes and how much of it comes from interest.

How this calculator works

Reaching a savings goal is mostly arithmetic: each month the balance earns interest, then your deposit is added. Interest is earned on the whole balance, so the earlier you start and the higher the rate, the fewer months the goal takes. The loop stops on the first month where the balance meets or exceeds the target.

For an emergency fund the rate is usually a high-yield savings account, where 4–5% APY is possible but changes with central-bank rates. For a longer-term goal held in investments, a return figure is an assumption rather than a guarantee — try 4% and 7% to see how sensitive the timeline is. The tool also flags the two failure cases: a goal already met, and a deposit so small relative to the target that it takes more than a century.

The formula

Iterate monthly: balance ← balance × (1 + r) + deposit, where r = APY ÷ 12 ÷ 100, until balance ≥ goal. Total deposits are current savings + monthly deposit × months; interest is the difference between the balance and the deposits. For a fixed timeline there is a closed-form annuity formula, but for “how long?” the loop is the clearest way to solve it.

Worked example

To reach 20,000 starting from 2,000 and saving 300 a month at 4% takes 54 months. By then you will have deposited $18,200; the other $1,911 comes from interest along the way.

Common mistakes

• Leaving the emergency fund in a 0.1% account. The rate matters less than actually saving, but moving from 0.1% to 4% APY can shorten a multi-year goal by months.
• Not adjusting the goal for inflation. A house deposit or car target in five years costs more than the number typed today. Add 2–4% a year to the target.
• Counting transfers as progress. Money moved from checking to savings is saving; money spent from savings is not. Track the net balance, not just deposits.