Savings goal calculator (how much to save monthly)
Find out how much to save each month to reach a goal by a deadline, accounting for returns.
If the initial amount already grows enough to reach the goal, the required monthly deposit is zero. Use your investment's expected net rate.
How the calculation works
The question is: "how much do I need to save per month to reach X by a date?". It's two steps, and interest works for you.
1. We subtract what the initial amount grows to on its own. 2. The remainder is divided by the deposit interest factor:
PMT = remainder ÷ [((1+i)ⁿ − 1) ÷ i]
Where i is the monthly rate and n the months. Since deposits earn along the way, you save less than the total divided by the months.
Step-by-step example
Goal of R$30,000 in 24 months, no initial amount, at 0.8%/mo:
- Factor: ((1.008)²⁴ − 1) ÷ 0.008 ≈ 26.3
- PMT: 30,000 ÷ 26.3 ≈ R$1,140/mo (without interest it'd be R$1,250)
Time is your biggest ally
Doubling the term cuts the required deposit by more than half, because compounding has longer to work.
Examples
- R$30,000 in 24 months at 0.8%/mo: ~R$1,140/mo.
- Same goal in 48 months: ~R$520/mo — double the term, less than half the deposit.
Frequently asked questions
What if I don't know the rate?
Use 0% for a conservative goal (saving without returns) or a realistic rate to see the effect of interest.
Where should I keep this money?
For short-term goals, something liquid and low-risk. Savings accounts yield less. See our CDI and fixed-income calculators.
Do I have to save the same amount every month?
The math assumes a fixed deposit. Raising it as income grows brings the goal much closer.
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Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources