Thanks for sharing. You allow the user to set the expected return (default of 7%) but assume zero volatility, which is unrealistic. I suggest adding an annualized volatility input -- for stocks you could use a default of say 18%. Ideally the output should show a range of outcomes, since stock returns are stochastic.
There is a forum called Bogleheads for financial planning by individual investors. I suggest presenting your calculator there.
There is a forum called Bogleheads for financial planning by individual investors. I suggest presenting your calculator there.