How much should I save each month to hit my goal?

Work backwards from your target: what monthly deposit reaches it on time, and what the total cost is.

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Monthly deposit needed
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Total you'll deposit
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Interest earned en route
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Final projected value
How is the required monthly deposit found?Solve FV = P(1+r)^n + PMT·((1+r)^n−1)/r for PMT. With $5k saved, $50k goal, 4% and 5 years the monthly need is about $662.
What if I already have enough saved?The tool returns a small/zero deposit and shows your current balance alone reaches the goal — you're done, or you can lower the rate and keep a buffer.
Why does rate barely change the answer on short horizons?Over 2–5 years compounding has less time to work. The bigger lever is the monthly deposit — which is why the tool emphasizes it.
Is this advice?Educational only. Your real rate varies; model a conservative rate to avoid missing the goal.