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Savings Goal Calculator

Enter a target amount, current savings, fixed monthly deposit and annual interest rate (APR) to see exactly how many months until you hit the goal, the balance at the moment you cross the line, how much you will have deposited and how much came from interest. Great for planning a down-payment, emergency fund, wedding, big trip, or retirement target.

Time to reach goal

Balance at goal

Total deposited

Interest earned

Principal + deposits Interest

Uses the standard future-value-of-an-annuity formula, assuming deposits at month-end and monthly compounding. Real returns vary with market volatility, tax and withdrawal limits.

Formula

Monthly rate i = APR / 12 Months to goal n = ln((G·i + C) / (P·i + C)) / ln(1 + i) Balance at goal = P·(1+i)^n + C·((1+i)^n − 1) / i P = current savings, C = monthly deposit, G = target amount When i = 0 the formula degenerates to n = (G − P) / C

Frequently asked

I want to save $500,000 for a down-payment in 3 years — how much should I put aside each month?

For a 36-month target starting from $0 at 4 % APR: nudge the monthly deposit up until "time to reach goal" lands on exactly 3 years (36 months). The break-point is about $13,070/month, with ~$29,500 of interest earned along the way. If you already have $100,000 in the account, the required monthly drops to ~$10,260. Bumping the rate to 6 % (typical index-fund average) cuts it to ~$12,560 but adds volatility risk. The numbers are nominal — 3 years of ~3 % inflation means today's $500k feels like ~$540k in three years, so adding a 10 % buffer is prudent.

Why does seeding the account with even a small amount shorten the timeline so dramatically?

Because P (current savings) compounds from month 0 while C (monthly deposit) only starts compounding the month after it arrives. Example with a $100,000 goal, $500/mo, 4 % APR: starting from $0 takes ~143 months (11.9 years); starting from $10,000 takes ~135 months (11.25 years) — a small upfront amount shaves 8 months and lifts interest earned from $28k to $36k. The reason is that the $10,000 compounds for the full 11 years, generating far more interest than the $500 × 8 = $4,000 of extra deposits you would have made. Practically: "lump sum + monthly" always beats "pure monthly", even when the lump is small.

Does chasing a higher yield (e.g. 7 % index funds) really shorten the timeline that much, and what is the trade-off?

Yes — the speed-up is substantial, but volatility is the price. Same $100,000 goal, $500/mo, starting from $10,000: 1 % APR (basic savings) → ~157 months; 4 % APR (time deposit) → ~135 months; 7 % APR (index fund average) → ~120 months. Going from 1 % to 7 % shaves more than 3 years off the timeline. The trade-off is real risk: index funds can drop 20–40 % in any given year, and if that drawdown lines up with your deadline (e.g. saving for a house), your portfolio may sit below the goal with no time to recover. Rule of thumb: money needed within 5 years → low-volatility (time deposit / short bonds); money for 10+ years → equity index funds are reasonable; 3–10 year horizons → some blend (e.g. 60/40 stocks/bonds).

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