Compound Interest Calculator for Traders

Project your trading account growth month by month with a consistent monthly or annual return, with or without periodic contributions. Visualize the power of compound interest and set realistic capital goals.

Compound Interest Calculator

Leave at 0 if you don't add capital monthly.

What does this tool calculate?

The Compound Interest Calculator projects how your trading account grows if you maintain a consistent monthly return over a defined period, with or without additional contributions. The result is not a prediction — it is a planning tool for setting realistic goals and understanding how much consistency matters over time.

The Compound Interest Formula

Without monthly contributions, the capital at the end of each month is:

Capital(n) = Initial Capital × (1 + r)ⁿ

With additional monthly contributions (C):

Capital(n) = Initial Capital × (1 + r)ⁿ + C × ((1 + r)ⁿ − 1) / r

Monthly % vs. Annual %

When you enter an annual return, the calculator converts it to the exact compounded monthly equivalent: r_monthly = (1 + r_annual)^(1/12) − 1. This is mathematically more accurate than dividing by 12.

The Power of Consistency

Compound interest rewards the trader with the most consecutive positive months, not the best single month. A trader with modest but consistent returns systematically outperforms one with large gains interrupted by large losses — the mathematical reason behind always respecting the stop loss.

A month with a −20% loss requires a +25% gain the following month just to break even. A month with −5% only requires +5.26%. The asymmetry of losses is the most powerful argument for strict risk management.
Legal Disclaimer: The results of this calculator are mathematical projections based on constant return assumptions and are strictly for educational purposes. In real trading, returns vary month to month and can be negative. This tool does not constitute financial advice and does not guarantee any result.