The problem is that projecting an investment portfolio into the future requires many assumptions. The most important of which is the rate of return you expect to earn on your investments. The second most important is what the inflation rate will be during that same time frame. While most people track stock market returns like a hawk, they don’t look at the other side of the coin. If the stock market returned 10% in one year, that’s great right? But what if inflation was 12%? Congratulations, your purchasing power decreased by 2%. Dammit!!!
In searching for high quality investment calculators online, I found that the majority are just too simple. They either don’t allow you to input a recurring payment (such as monthly or quarterly), or they don’t take into account inflation, or they don’t allow you to differentiate what your returns would be between stocks and bonds, etc. Most of these online calculators just don’t have enough customization options to truly get a picture of what an individual’s future portfolio could look like. Therefore… they’re useless! Plain and simple! These calculators are about as good as a large pile of mierda.
So I wrote my own portfolio and retirement spreadsheet, and I made it customizable. Take a look at the input screen below. You’ll notice that it allows you to specify a payment frequency, as well as a growth rate. It will take into account your allocation between stocks and bonds, and the corresponding returns. It allows you to input an inflation rate. And best of all, it allows you to build up a projected portfolio value, and then analyze it using three different retirement approaches.