Money, Explained From the Inside

Tools / Save & grow / Chapters 8 and 25

Goal calculator

Turn a goal (a deposit, a course, a cushion) into a monthly number, and see how a different timeline or return changes it.

1 · The idea

Required monthly saving

First grow what you already have. Whatever is still missing must come from monthly contributions, each growing for the time left. The formula solves for the contribution.

The formula

C = (Target − P × (1 + i)^n) × i ÷ ((1 + i)^n − 1)

Target
amount you want
P
amount you already have
i
monthly return
n
months until the goal

2 · A worked example

To reach $60,000 in 8 years from $5,000 at 4%: $472.16 a month. At 0% growth it would take $572.92; time and return carry the difference.

3 · Now use your own numbers

Change anything. The result updates instantly.

Save each month
$472.16
With no growth you would need
$572.92
If the goal is in today’s prices
$588.55Target becomes $73,104 after inflation
Total you put in
$50,327Growth supplies the rest

What this means

Growth does less than people expect over short horizons and far more over long ones: compare the first two numbers.

If the monthly figure is out of reach, change the date first, then the goal, and only then the assumed return.

Illustrative, not personal advice. Inspired by Chapters 8 and 25 of Money, Explained From the Inside. Your figures stay in this browser. Real products add terms, taxes and conditions that this simple model leaves out.

4 · Take care

What this tool can’t see

  • Short goals belong in safe, reachable savings: accept a low return rather than risk the goal.
  • If the goal is in future money, raise the target for inflation.

5 · Go further

Where this fits

See it in a life:

MariaThe quiet power of margin Anir & KatiaThe biggest decision of their lives

Private to this device. Nothing is sent anywhere.

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