For those on the East and West coasts, that sum will last less than two decades.

Once a nest egg hits the $1 million mark, most soon-to-be retirees assume they are set. Depending on where you live, that may not be enough.

Considering that many families spend more than 100 percent of their income after taxes on monthly expenses alone, personal finance site GoBankingRates measured how long $1 million in savings would last in cities across the country by comparing average expenses for people age 65 and older, including groceries, housing, utilities, transportation and health care.

Dollars stretched the furthest in cities like Houston, Austin, Texas, and Memphis, Tennessee, where annual expenditures were around $40,000 a year.

Top 5 cities where $1 million will last the longest:

1. Houston

$1 million will last: 25 years, 11 months

2. Oklahoma City

$1 million will last: 24 years, 7 months

3. Austin, Texas

$1 million will last: 24 years, 6 months

4. Tulsa, Oklahoma

$1 million will last: 24 years, 4 months

5. Memphis, Tennessee

$1 million will last: 24 years, 3 months

It's little surprise that retirees could blow through $1 million much faster in hotspots like New York, Boston and San Francisco by spending upward of $55,000 annually just getting by.

Top 5 cities where $1 million will last the shortest:

1. New York

$1 million will last: 17 years, 6 months

2. Boston

$1 million will last: 17 years, 11 months

3. San Francisco

$1 million will last: 17 years, 11 months

4. Philadelphia

$1 million will last: 18 years, 0 months

5. San Jose, California

$1 million will last: 18 years, 2 months

Alternatively, a separate analysis by GOBankingRates found the most affordable retirement spots overseas. Among countries that offer both low costs of living, plus the ability to receive Social Security income, Egypt topped the list.

Go for the pyramids. Stay for the inexpensive rent and favorable tax treatment.

More from Personal Finance:

When a $1 million retirement nest egg isn't enough

Older Americans worry that rising debt threatens their retirement

For retirees, here's how to score a side gig

