🎯 Savings Goal Calculator
How much to save monthly to reach a goal with compound interest. Runs privately in your browser.
Solving backwards from your goal
The calculator treats your goal as a future value and solves backwards for the monthly deposit required to get there, assuming deposits are made at the end of each month and the annual return is constant and compounded monthly. Starting savings earn compound growth the whole period, which is why a head start reduces the required monthly amount disproportionately.
Because it assumes a constant return, treat the answer as a planning baseline. For a conservative plan, re-run it at a lower return; if the required payment is still comfortable, your goal is robust to market noise.
The required-deposit formula
Required monthly deposit: PMT = (FV − PV × (1 + r)^n) × r / ((1 + r)^n − 1), where FV is the goal, PV is current savings, r is the monthly rate (annual ÷ 12) and n is the number of months. With a 0% return it reduces to (FV − PV) ÷ n.
Reaching 50,000 in eight years
Goal: 50,000 in 8 years, starting from 5,000, expecting 5% a year. The monthly rate is about 0.4167% over 96 months. Your starting 5,000 grows to roughly 7,453 on its own, leaving 42,547 to fund. The calculator shows a required deposit of about 361 per month. With no starting savings the same goal needs about 425 per month — the head start is worth roughly 63 a month.
Optimistic assumptions and other errors
- Using an optimistic return assumption. Long-run diversified portfolio returns of 5–7% are common planning figures; 10%+ is speculative.
- Ignoring that the goal itself may inflate. If your target is a house deposit, prices may rise while you save.
- Saving in cash for decades. At 0–1% returns the required monthly amount is much higher — see the difference by re-running at 0%.
- Forgetting emergencies. A plan with zero buffer fails at the first car repair; keep a separate emergency fund.
Savings questions
Does the monthly amount assume deposits at the start or end of the month?
End of month. Beginning-of-month deposits would need slightly less each month.
Can I include an existing balance?
Yes — the starting savings field is compounded for the full period before deposits are considered.
What return should I use?
For cash savings, 0–2%. For diversified investments, 4–6% is a commonly used conservative planning figure. Run two or three scenarios.
Does this account for tax on interest?
No. Returns here are pre-tax; taxable accounts may net less depending on your jurisdiction.
What if I can only save half the required amount?
Extend the deadline, lower the goal, or raise the expected return — the calculator lets you test each lever quickly.
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Tip: double-check inputs before relying on results for important decisions.