Savings Goal Calculator (time to reach target)
Enter your goal, current balance, monthly savings, and expected annual return. The calculator solves for the number of months until you hit the target.
- Total months
- 154
- Total contributed
- $77,000
- Interest earned
- $23,000
How it works
How time-to-goal is computed
The standard future value formula is FV = P × (1 + r)^n + M × ((1 + r)^n − 1) / r, where P is starting balance, M is monthly contribution, r is monthly rate (annual / 12), and n is months. Setting FV = your goal and solving for n gives n = log((G × r + M) / (P × r + M)) / log(1 + r).
When the rate is zero, the formula collapses to (G − P) / M months. The calculator picks the right path automatically and rounds up to the nearest whole month, since you can't 'partly' make a monthly contribution.
What matters most: monthly contribution or rate?
For typical savings horizons (1-10 years), monthly contribution dominates. Going from $300 to $500 per month makes a far larger difference than going from 3% to 5% return. Time and contribution are linear; rate is exponential but only over very long horizons.
For 20+ year goals (retirement, college funds), rate becomes king. The same $500/month for 30 years produces vastly different totals at 4% vs 8%. This is why early retirement savings are exponentially more valuable than later ones.
Realistic rates
High-yield savings: 4-5% in current US rates. Money market funds: similar. CD: 4-5% locked. Government bonds: 4-5% but lock period longer.
Diversified stock index (S&P 500 historical average): about 10% nominal / 7% real. Use 6-7% for conservative planning.
Inflation eats 2-4% per year. For 'today-dollar' goals, subtract expected inflation from your nominal rate.
Frequently asked questions
›Why is the answer rounded up to whole months?
Because you can't make a partial monthly contribution. If the math says 32.4 months, you'll actually hit your goal in month 33 (assuming consistent contribution).
›What rate should I use?
For high-yield savings: 4-5%. For S&P 500 long-term: 6-8%. For ultra-conservative: use 0% to see how long pure savings takes.
›Should I include inflation?
If your goal is in today's dollars, subtract expected inflation from your rate (e.g., 7% nominal − 3% inflation = 4% real). The calculator gives a 'real' purchasing-power answer that way.
›Does this assume monthly compounding?
Yes — interest compounds at the same monthly cadence as your contributions. For most savings products this matches reality closely.
›What if I save 0 per month with 0 rate?
Then you can't reach a goal above your starting balance. The calculator returns no result in that case.
›Is the interest taxable?
In most jurisdictions, yes (unless in a tax-advantaged account like 401(k), IRA, NISA, etc.). Consider after-tax rate if your goal is post-tax purchasing power.
›What if my contribution amount changes?
Run the calculator multiple times for each phase. For variable contributions, a financial planning spreadsheet is more flexible.
›Does the data leave my browser?
No — calculations run locally.
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