Savings goal calculator
Work out the contribution needed to hit a savings goal: enter the target, what you already have, the annual return and the horizon, choose monthly or yearly contributions at the start or end of each period, and get the required contribution, projected balance, shortfall, total invested, interest and a period-by-period schedule — plus how many periods a given contribution needs.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Goal and inputs
All money is integer cents; each period’s return is the opening balance (plus the contribution when you pay at the start) times the period rate, rounded to the cent, and the required contribution is the smallest amount that still hits the goal.
Result
164,700.95835,299.055,379.231,000,000.02645,507.60254,492.421200.416667%Period schedule
120 periods in total; only the first 12 are listed.
| Period | Opening | Contribution | Interest | Closing |
|---|---|---|---|---|
| 1 | 100,000.00 | 5,379.23 | 416.67 | 105,795.90 |
| 2 | 105,795.90 | 5,379.23 | 440.82 | 111,615.95 |
| 3 | 111,615.95 | 5,379.23 | 465.07 | 117,460.25 |
| 4 | 117,460.25 | 5,379.23 | 489.42 | 123,328.90 |
| 5 | 123,328.90 | 5,379.23 | 513.87 | 129,222.00 |
| 6 | 129,222.00 | 5,379.23 | 538.43 | 135,139.66 |
| 7 | 135,139.66 | 5,379.23 | 563.08 | 141,081.97 |
| 8 | 141,081.97 | 5,379.23 | 587.84 | 147,049.04 |
| 9 | 147,049.04 | 5,379.23 | 612.70 | 153,040.97 |
| 10 | 153,040.97 | 5,379.23 | 637.67 | 159,057.87 |
| 11 | 159,057.87 | 5,379.23 | 662.74 | 165,099.84 |
| 12 | 165,099.84 | 5,379.23 | 687.92 | 171,166.99 |
What this tool does
- Set a 1,000,000 goal: with 100,000 saved and a 5% return over ten years, you need 5,379.23 a month, which lands on 1,000,000.02.
- See what your savings do on their own: 100,000 at 5% becomes 164,700.95 in ten years, so 835,299.05 is the real gap your contributions must fill.
- Compare monthly with yearly: the same goal needs 66,554.12 a year, slightly more than the monthly route, purely because of when the money arrives.
- Reverse the question: if you can only put away 8,000 a month, the million takes 89 periods — about 7 years and 5 months.
Example
Input
Goal 1,000,000, already saved 100,000, 5% annual return, 10 years, monthly contributions at the end of each period
Output
Current savings grow to 164,700.95; shortfall 835,299.05; contribution 5,379.23 per period; projected balance 1,000,000.02; total contributed 645,507.60; projected interest 254,492.42; 120 periods; period rate 0.416667%
The contribution is the smallest whole cent that still reaches the goal: 5,379.22 only gets to 999,998.47, a single cent short, so the tool returns 5,379.23, which overshoots by 0.02.
Frequently asked questions
Why does the projected balance overshoot the goal slightly?
Money comes in whole cents while goals rarely divide evenly. The tool binary-searches integer cents for the smallest contribution whose projection is at least the goal: one cent less falls short, one cent more overshoots by a hair (0.02 in the example). That way following the number never leaves you short.
How much does beginning-of-period versus end-of-period matter?
Paying at the start means the contribution earns that period’s return, so you need less each period (5,356.91 instead of 5,379.23 in the example). An automatic transfer on payday is the classic start-of-period case.
Is monthly or yearly better?
At the same annual return, the more often and the earlier money arrives, the longer it compounds. For a million over ten years at 5%: monthly contributions total 645,507.60, while yearly contributions total 665,541.20 — about 20,000 more, purely because the money sits in the account for less time.
Can the return be zero or negative?
Zero is fine, and it reduces the maths to arithmetic: a 1,200,000 goal over ten years needs 1,200,000 ÷ 120 = 10,000 a month. Negative returns are not supported, because saving towards a goal while the balance shrinks is a different model that needs far more periods and is easy to misread.
Why does the reverse calculation say the goal is unreachable?
If the contribution you can make is zero or too small, the balance cannot reach the goal within 1200 periods (100 years), so the tool says so. Enter a larger contribution, shorten the horizon or lower the goal and try again.
Keywords：savings goalmonthly savingscompound savingshow much to savegoal seek储蓄目标每月存多少存钱计算器资金缺口定投目标