You may be mentally and emotionally ready to retire, but if you're not financially ready, your retirement may not be the relaxing time you'd hoped for. Being truly ready to retire means having a thorough grasp of how much money you need and the savings to back it up. Here are three signs that you're not quite there yet.

You don't have a retirement plan

You may have a vision of what you want your retirement to look like, but if you haven't budgeted for it, you're unlikely to reach your goal. The tricky part about retirement planning is you can't know with certainty how long you will live or how much money you'll need each year. The best you can do is to estimate and reevaluate your estimates periodically to ensure that they reflect your lifestyle and goals.

Mature man looking overwhelmed

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The average life expectancy in the U.S. is just shy of 79 years, but this may be an underestimate for many. One in four 65-year-olds will live past 90, according to the Social Security Administration, and one in 10 will live past 95. Use these numbers as a baseline and adjust up or down based on your lifestyle and family health history. If you're pretty healthy, plan to live to at least 90, just in case. Once you've got your life expectancy estimate, subtract the age you plan to retire at to determine how many years of savings you need.

Then, you need to approximate your living expenses. Add up the annual cost of your expected living expenses in retirement, keeping in mind that some expenses that you have now, like child care, may go away by then. Next, you have to factor in inflation. It's impossible to predict this with accuracy, but you can use 3% per year as an estimate. If, for example, your retirement expenses are $40,000 this year, they would be $41,200 the next year, and so on. Calculate your living expenses for every year of retirement up to your planned life expectancy and then add them together. If this all sounds too complicated, you can use a retirement calculator to estimate how much money you need.

Don't forget to account for things like taxes and healthcare costs. Fidelity estimates that the average 65-year-old couple retiring today will need $280,000 to cover their medical expenses, and this number will likely continue to rise. You also don't want to forget about Social Security. You can estimate what your Social Security benefit will be by creating a my Social Security account. Subtract the amount you expect to get from Social Security from your total estimated living expenses to figure out how much you need to save on your own.

You have a lot of debt

It's not that you can't retire with debt, but you should avoid this whenever possible. Debt can put an additional strain on your finances, which may already be tight. If you have a mortgage in retirement and you run out of money to cover your payments, you could end up losing the roof over your head.

Do what you can to pay down your debt, especially high-interest debt, before you retire. This may mean making lifestyle changes, like cutting frivolous expenses or pushing back your planned retirement date by a few years. It's not ideal, but you'll be glad you did it when you see how much it reduces your living expenses.

You don't know when you should take Social Security

You become eligible for Social Security at age 62, but you won't receive your full benefit amount if you start claiming at this age. Full retirement age is 66 or 67, depending on the year you were born. For every month that you claim up to 36 months before this age, your benefits are reduced by 5/9 of 1%. For every month above 36 years, the reduction is 5/12 of 1%. For instance, If you start claiming at 62 and your full retirement age is 66, you'll only receive 75% of your scheduled benefit per check, and you'll only receive 70% if your full retirement age is 67.

But this works the opposite way too. You can delay your Social Security payments past your full retirement age and your checks will increase by 2/3 of 1% per month. This maxes out at age 70 when you receive 124% or 132% of your scheduled benefit, depending on whether your full retirement age is 67 or 66, respectively.

You should have a plan for when you're going to start Social Security because this will affect how much money you need to save on your own for retirement. You're free to start benefits as early or late as you want, but it's important to understand the consequences of your choice. If you're trying to maximize your benefits, you may be better off delaying Social Security until your full retirement age or age 70, but if you don't plan to live as long, you may want to start early.

Retirement planning is complex and it takes time to get it right. But it's important that you do. If you answered "yes" to any of the statements listed above, take steps to correct these issues now before it's too late. Your future security depends on it.