Most people vastly underestimate two important numbers: how much money they'll actually need to retire at their intended quality of life, and how many years it'll actually take to stash away that much money.

Social security kicks in at age 62, so most people just assume that they'll be able to retire then. But unless you're actively saving a big chunk of every paycheck, you may not be able to retire even at that age.

Just see the Early Retirement Grid by Four Pillar Freedom to see what that means:

early-retirement-grid

To use this grid, all you need is two pieces of information: your post-tax annual income and your annual expenses. Once you have those, simply find the intersection on the grid -- and you'll know how many years it will take for you to retire assuming you invest 100% of the difference towards retirement!

So assume you earn $50,000 post-tax and spend $45,000 every year on bills, food, car, entertainment, etc. If you invested the other $5,000 into retirement year after year, you'd be able to retire in just over 51 years. If you slashed your spending to $35,000 and invested $15,000 per year, you could retire 23 years sooner!

Note that this grid assumes that you're starting at $0 net worth. If you have debt, it will take you even longer. If you already have a lot of retirement savings, you obviously won't need as many years.

Website -- Early Retirement Grid by Four Pillar Freedom

Are you on track to retire when you thought you would? Or was this the wake-up call that you needed to start saving more responsibly? Let us know in the comments!

Image Credit: Nattapol Sritongcom via Shutterstock