Saving for retirement isn't easy, especially when you have a neverending list of other financial responsibilities to take care of.

However, considering that nearly half of baby boomers have no savings at all, according to a survey from the Insured Retirement Institute, it's crucial to start planning for your senior years long before retirement. And these three mistakes could put you at risk of running out of money later in life.

Older couple looking at documents and a calculator

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1. Not setting a savings goal

It's tough to prepare for retirement when you don't know how much you should be saving. Even if you do have a target in mind, it's important to be sure you've estimated that number as accurately as possible.

Around 46% of workers who have a savings goal say they simply guessed at their retirement needs, according to a survey from the Transamerica Center for Retirement Studies. A savings goal is only useful if it's at least relatively accurate, and although you may not be able to predict exactly how much you'll spend throughout retirement, coming up with an educated guess is a good start.

To determine a savings goal, run your numbers through a retirement calculator. Be sure to factor in other sources of income too, such as Social Security benefits or a pension, to figure out how much of your income will need to come from your savings.

2. Underestimating general living expenses in retirement

A common rule of thumb is to assume that in retirement, you'll spend around 75% to 85% of what you're currently spending. As you're calculating your savings goal, you might use this estimate to determine how much you'll spend each year.

However, while this guideline may be accurate for some people, it could be significantly less than what you need depending on your lifestyle. You might spend less in retirement than you do now, but you could also spend substantially more -- especially if you plan to travel extensively, pick up expensive new hobbies, or move to a new city with a higher cost of living.

It can be tough to estimate exactly how much you'll spend every year in retirement,but think about how your lifestyle may change. It may also be helpful to create a retirement budget, mapping out all the expenses you can think of in retirement to get a better idea of how your future costs will compare to your current spending levels.

3. Forgetting about inflation

Inflation is a secret expense that can potentially wreck your retirement plans. Your money won't be worth as much in the future as it is now, so even if it seems like you have plenty of savings to last the rest of your life, you may not have as much as you think.

Say, for example, you expect to spend around $50,000 each year in retirement. After 30 years, assuming a 2.5% annual inflation rate, that $50,000 per year in today's dollars will actually be worth nearly $105,000 per year in 2050. In other words, you'll likely find yourself spending more each year just to maintain your lifestyle thanks to inflation.

Many retirement calculators will factor inflation into your spending goal, so it's a good idea to double-check that you're accounting for this cost.

It's never too early to start saving for retirement, but it's important to plan carefully. These three mistakes could throw a wrench in your plans, and by preparing for them now, you'll give yourself a better chance of enjoying a financially secure retirement.