Show HN: Estimate the money you will make thanks to compound interests

I made a similar one for personal use — https://www.dffrnt.com/maxculator/

I actually use it more than I thought I would. Some cases where it helped:

• Last year I invested some money in Govt. bonds at 9% interest. The catch was the interest won’t be compounded. Using this app I was able to quickly estimate what an equivalent FD interest would be (about 8%, which is not a good deal given current inflation here in India)

• Estimate the effects of Inflation. Avg. CPI inflation over the past 4 years has been hovering around 5%. Plugging in the numbers (100, 5 and change duration value until result pane shows 200) tells me how much time it takes for me to lose half my money to inflation (just over 14 years)

• Reflect on luxury purchases. I often get tempted to buy the iPhone X and Apple Watch along with an upgrade for my 4 year old MacBook Air. The total cost comes to 200k INR which, while affordable, is still a non-trivial amount. Plugging in the numbers (200k, 8% FD, 3 years of patience), I get 250k at maturity which will allow me to buy all of the above items and still have 50k left (worth 4 years of supplements.)

• Interesting trivia. Plug in 100, 8% FD, and keep changing the duration until the Effective Interest Rate field reaches 100%. This duration, 51 years, shows how long it’d take for the compounding (@8%) to be so large that my money basically doubled each and every year.

Doesn’t seem to work on iOS Safari; I don’t see a submit button anywhere. Nor do I see any result when I change the values.

I have been trading for some months so I built this calculator to know how much I can make over the time. I also use it to illustrate the power of compound interests. Kindly let me know what you think. Christ from Congo-Brazzaville