This early retirement calculator can determine how many years remain before you can retire, based on just your savings rate.
Inspired by the Mr. Money Mustache article, “The Shockingly Simple Math Behind Early Retirement,” and the now-defunct Networthify early retirement calculator (an Internet Archive version is available), this simple calculator only requires your savings rate, measured as a percentage of your take-home income, to determine how many years it will take before you can retire.
You can also input your current total savings, as measured in years of take-home pay, as well as your expected annual rate of return and safe withdrawal rate. You do not have to provide your age, but it is used to calculate the age at which you can retire.
The annual rate of return reflected your investment gains, excluding inflation, and defaults to 6%. By comparison, the S&P 500 historically returns about 7% annually.
The calculator assumes that you save consistently at your stated savings rate throughout the year and that your investment gains also accrue evenly throughout the year.
Once the calculator determines the first year in which you can withdraw 100% of your current annual spending (which is indirectly determined by your savings rate) at your safe withdrawal rate, it outputs the number of years remaining until you retire as well as your expected age and calendar year of retirement.
The safe withdrawal rate defaults to 4%, and is the rate at which you can withdraw your accumulated savings without ultimately running out of money. A 4% safe withdrawal rate is considered a good rule of thumb. For a more conservative estimate, use a safe withdrawal rate of 3% or 3.5%.