Hi and thanks for taking the time to solve my problem. I am creating a wealth management tool, and as promised, solving my problem will reward you a free copy of my tool. It's very useful and glad to hear feedback

Question is this:

If I invest 100$ in to an index fund for example, and it gives me an annual return of say 6%, which is the formula that will provide me with the monthly return. I know how to calculate compound interest annually, but I need monthly compounding because in my tool monthly payments do not need to be equal.

So basically if in January you invest 25$ and in February 50$ and 75$ and so on, whatever the amounts may be... How can I calculate exact estimation based on for example 6% APR per month

Month investment Compound investment 6% APR per month
1 25 25,00 ?
2 50 75,00 ?
3 75 150,00 ?
4 100 250,00 ?
5 125 375,00 ?
6 150 525,00 ?
7 175 700,00 ?
8 200 900,00 ?