Capital planning tool

Compound Calculator

Simulate how a balance grows from your initial capital, return rate and period. You can compare it against simple interest on the chart, or work backwards from a target to the rate you need.

  • No registration
  • Free
  • Calculated in your browser

Compare against simple interest on the chart

Inputs

JPY
5.0%
0.1%15%30%
mo.
JPY

Results update as you type

Result

Final balance

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-

Total profit

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Total return

-%

Total principal

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Assessment:
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-

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Balance growth chart

Compares three lines: compound (profit added back to the principal), simple (profit withdrawn) and the principal itself. The gap widens the longer the period.

Period by period

Balance and profit for each period

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How to read this result

  • What compounding is

    Adding the profit you make back to the principal and trading it again next period. At the same rate, the gap against simple interest grows with the length of the period.

  • What the total return means

    Profit / (initial capital + all additions). Money you pay in also counts as principal, so the percentage falls as you add more.

  • Points to watch

    This is a theoretical figure that assumes exactly the same rate every period. Real trading has losing periods and will not follow this curve.

Method and specification

  • Main inputs used

    Initial capital / Return rate / Investment period / Addition per period. The addition is applied after each period has finished.

  • When to use it

    Planning your capital / Finding the rate a target needs / Checking the gap between simple and compound interest

  • Notes

    Working back from a target uses a binary search to find the required rate. Tax, commission and swap are not included.

Frequently Asked Questions

What monthly return is realistic?

Around 1-5% per month is generally treated as the realistic range. A return above 10% a month may be possible for a while, but it is not a level you can sustain for long. This tool shows a theoretical figure that assumes the same rate every month, so allow for losing months in real trading.

What is the difference between compound and simple interest?

Compounding puts the profit back into the principal and trades it again in the next period. Simple interest withdraws the profit and keeps trading the principal only. The two lines on the chart show that difference. It is small over short periods and grows sharply the longer you run.

How does a regular addition change the calculation?

The addition is applied after each period has finished, so the money you add is not part of that period's profit and starts working from the next one. Total return is profit / (initial capital + all additions), so the more you add, the lower the total return percentage becomes.

Once your money management is settled, the next step is choosing an EA.

Browse free EAs and the rankings to compare the approach that suits you.

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