Experts have revealed the key to a comfortable retirement - and how much money one has to earn by specific age milestones to achieve it.

In order to say goodbye to the workforce by age 67, Fidelity Investments recommended saving 10 times one's yearly income by then, CNBC reported.

The retirement plan provider has broken down how much someone needs to save by key ages leading up to retirement .

By 30 years old, an individual should have saved the equivalent of their annual salary. For example, if someone has been earning $60,000 each year, they should have $60,000 in their savings.

Ten years later, one should have three times their annual income saved. So, while earning $60,000, that person should have $180,000 in the bank for retirement.

When a person reaches 50, they need six times their income put away. Based on the example salary, they should have $360,000.

By age 60, it is recommended to have eight times one's annual earnings in their retirement fund. That is $480,000 making $60,000 a year.

Finally, when 67 rolls around, Fidelity Investments said a retiree should have 10 times their income saved - comfortable hypothetical $600,000 -  to live off of for the rest of their lives.

Experts suggest saving 15 percent of one's pre-taxed income every year in order to achieve the ultimate goal of saving enough for retirement. This include any 401(k) matches from employers.

These savings rates would have to be adjusted if someone planned on retiring earlier or later than 67. The earliest someone is able to retire and claim social security is 62 years old.

The average age of retirement in America is 65 for men and 63 for women, Fidelity Investments reported.

The retirement plan provider said this advice does not account for pay fluctuation along the way, as it is impossible to determine how much every person's salary will change over the course of their career.

The example income was kept consistent for clarity purposes.

'Our guidelines assume no pension income, and we make a number of other assumptions, including continuous employment, uniform wage growth, and contribution amounts increasing with the wage growth,' Fidelity Investments wrote.

'We acknowledge that individual circumstances are different and may vary through time.'

This model also assumed than more than 50 percent of savings got invested into stocks and that an individual started saving at 25 years old.

Fidelity Investments said their are four key factors to consider when calculating how much is needed for retirement: a yearly savings rate, savings milestones, an income replacement rate and a sustainable withdrawal rate.

Social Security provides income-based retirement payments, but people must depend on their savings for the rest.

Every year one delays their retirement between ages 62 to 70, Social Security monthly benefits increase by 8 percent.

At least 45 percent of one's pre-retirement income can be accounted for by Fidelity Investments' estimate, according to the retirement plan provider.

When it comes to finally spending all that hard-earned money, experts said to be cognizant to to spend it to fast or too slow.

If the money is spent too quickly, a person may 'risk running out of money,' the investment firm said.

But if it is spent too frugally, one may not properly enjoy the retirement they thoroughly planned for.

Experts suggested limiting withdrawals to four or five percent of initial retirement savings and adjusting the rate based on inflation.

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