Determine what dollar amount you have to save and what percentage of your pay would have to be saved if you earned either 8% or 10% return on your investments. 

In order to determine how much money one needs to save in order to reach a desired rate of return from investments, it is important to first take into account their financial position and their retirement plans. It is important to consider factors such as the expected lifestyle, income and expenditures. After all this information is considered, you can use the data to determine how much capital will be needed to achieve your desired return rate.

If, for example, an individual earns $100,000 per year and has no savings, but wants to get a return of 8% or 10% on his investments, then he would have to set aside between $312,500 to $400,000. To reach their goals, they will need to save between 31 and 40% of current income each year over a period of 30 years.

These figures should be considered estimates, and they could vary depending on external factors like inflation or the market. Individuals should therefore regularly review their financial situation to make sure they stay on track and minimize the risks of investment portfolios while also achieving long term goals.