Key Biscayne, FL vs Mountain Brook, AL: Cost of Living

Which city costs less?

Mountain Brook, AL has a modeled overall cost index 27.3% lower than Key Biscayne, FL.

Key Biscayne, FL · modeled 2BR rent: $3,450 / month
Mountain Brook, AL · modeled 2BR rent: $1,900 / month

These are saved estimates, not current rental listings. Some cities use adjusted regional data. Your household budget can differ from the overall index. Sources and assumptions

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Cost of Living Comparison 2026

Compare Key Biscayne, FL and Mountain Brook, AL using saved regional data and explicit budgeting assumptions. Rent estimates are not live listings. Change the salary below, then check the source notes before applying a result to your household.

Saved regional estimates · Sources and assumptions

Current salary in Key Biscayne, FL

Numbers update automatically as you type

Estimated savings: $1,961/month in Mountain Brook, AL

$150,000 in your current city has a modeled equivalent of $126,469 in Mountain Brook, AL

Regional cost estimates: Key Biscayne, FL uses Miami, FL. Mountain Brook, AL uses Birmingham, AL. Available city ZIP rent estimates are shown separately.

Overall Cost

↓ 27.3%

Less expensive

Monthly Impact

$1,961

Savings

Annual Impact

$23.5K

Per year

Assumes 60% of current gross income goes to living costs. The headline uses the category budget below; taxes, moving costs and savings goals are excluded.

Key Biscayne, FL

Population:14K

Cost Index:

113.9

100 = national average

Typical Home:$1.62M

Mountain Brook, AL

Population:22K

Cost Index:

82.8

100 = national average

Typical Home:$865K

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Key Biscayne, FL

The Sunshine State

14K

Population

State Tax

No Income Tax

Located in Florida, this city has a population of 14K residents.

💡 Advantage: Florida has no state income tax!

Mountain Brook, AL

The Heart of Dixie

22K

Population

State Tax

Yes

Located in Alabama, this city has a population of 22K residents.

Cost Breakdown by Category

Estimated monthly spending: Key Biscayne, FL vs Mountain Brook, AL

Assumes 60% of your current gross income is spent on these categories. The headline and totals use this same budget. Rent estimates below are separate reference data. Rounded amounts may differ by $1.

Category	Key Biscayne, FL	Mountain Brook, AL	Difference	Change
Housing	$2,723/mo	$1,459/mo	↓ $1,264less	46.4%
Other	$1,715/mo	$1,326/mo	↓ $389less	22.7%
Transportation	$1,198/mo	$1,013/mo	↓ $185less	15.4%
Groceries	$920/mo	$829/mo	↓ $90.74less	9.9%
Healthcare	$502/mo	$444/mo	↓ $57.22less	11.4%
All Utilities	$442/mo	$467/mo	↑ $25.07more	5.7%

Housing

↓ 46.4%

Key Biscayne, FL

$2,723

Mountain Brook, AL

$1,459

Difference

$1,264

less

Other

↓ 22.7%

Key Biscayne, FL

$1,715

Mountain Brook, AL

$1,326

Difference

$389

less

Transportation

↓ 15.4%

Key Biscayne, FL

$1,198

Mountain Brook, AL

$1,013

Difference

$185

less

Groceries

↓ 9.9%

Key Biscayne, FL

$920

Mountain Brook, AL

$829

Difference

$90.74

less

Healthcare

↓ 11.4%

Key Biscayne, FL

$502

Mountain Brook, AL

$444

Difference

$57.22

less

All Utilities

↑ 5.7%

Key Biscayne, FL

$442

Mountain Brook, AL

$467

Difference

$25.07

🏠Rent Comparison

Studio

From$2,590

To$1,540

↓ $1,050

1 Bed

From$2,820

To$1,730

↓ $1,090

2 Bed

From$3,450

To$1,900

↓ $1,550

3 Bed

From$4,420

To$2,380

↓ $2,040

Key Biscayne, FLZIP-level data

1BR range: $2,820–$2,820/mo

Mountain Brook, ALZIP-level data

1BR range: $1,730–$1,730/mo

💡 Note: HUD Fair Market Rents estimate 40th-percentile gross rents, including most tenant-paid utilities. City ZIP summaries are medians of those estimates, not market median rents. Actual prices vary by neighborhood, amenities, and condition. Source: HUD Small Area Fair Market Rents FY2026.

$7,500

Monthly in Key Biscayne, FL

$5,539

Monthly in Mountain Brook, AL

$1,961

Difference

Home Values

Key Biscayne

Mountain Brook

$1.62M

Median Value

$865K

↓ -3.1%

YoY Change

↑ +5.3%

↑ +48.2%

5-Year Change

↑ +39.2%

Homes in Mountain Brook are 47% less expensive than Key Biscayne

Calculate payment - Key Biscayne Calculate payment - Mountain Brook

Source: Zillow Home Value Index (ZHVI), January 2026

Tax Comparison

Annual tax burden comparison at $150.0K salary

Tax Savings

↓ $7.5K

More taxes

Monthly Difference

$622

Less take-home

Effective Rate Diff

5.0%

Rate difference

Key Biscayne, FL

Federal Income Tax

Effective: 18.9%

$25.5K

Florida State Tax

No state income tax

FICA Taxes

Social Security + Medicare

$11.5K

Total Taxes

Effective: 24.7%

$37.0K

Take-Home Pay

$9,416/month

$113.0K

Mountain Brook, AL

Federal Income Tax

Effective: 18.9%

$25.5K

Alabama State Tax

Effective: 5.0%

$7.5K

FICA Taxes

Social Security + Medicare

$11.5K

Total Taxes

Effective: 29.6%

$44.5K

Take-Home Pay

$8,794/month

$105.5K

Additional Tax Information

Key Biscayne, FL Tax Rates

Sales Tax:7.2%

Property Tax:0.8%

Mountain Brook, AL Tax Rates

Sales Tax:9.1%

Property Tax:0.4%

💡 Note: Tax calculations are estimates based on 2024/2025 tax brackets for single filers with standard deduction. Actual taxes may vary based on filing status, deductions, credits, and local variations.

Environment

Key Biscayne

Mountain Brook

48 Good

Air Quality

57 Moderate

59.8%

Good Air Days

26%

100 Very High

Climate Risk

98 High

🌊🌅🌀

Top Hazards

🌊🌡🌪

▲+2.3°F

2050 Outlook

▲+2.5°F

15 days

Heat Days >95°F

41 days

▲+2.3°F

2050 Outlook

▲+2.5°F

15 days

Heat Days >95°F

41 days

Before moving from Key Biscayne, FL to Mountain Brook, AL

Use this comparison to shortlist a move, then check the costs that depend on your household.

Compare actual homes. Get current quotes in Mountain Brook, AL for the same bedroom count and included utilities as your home in Key Biscayne, FL. Add parking, deposits, insurance and any overlapping leases. The rent estimates above are a starting point, not available listings.
Confirm your income. Check your expected pay with your employer, including any location adjustment. Use “Different salary at destination?” above to compare two incomes. The budget model excludes taxes and one-time moving costs; it is not a take-home-pay calculation.
Price your daily routine. Check the commute from a specific address to work, school or childcare. Add household expenses missing from this model, such as childcare, debt payments and medical needs. Verify local services before signing a lease.
Plan the transition. Get moving quotes and budget for travel, setup costs and time off. Open your Key Biscayne to Mountain Brook moving checklist to organize the tasks and timing.

Still choosing a destination? Explore cities similar to Mountain Brook, AL by cost, housing, population and region.

Frequently Asked Questions: Key Biscayne, FL vs Mountain Brook, AL

How do the cost estimates for Key Biscayne, FL and Mountain Brook, AL compare?

Mountain Brook, AL has a modeled overall cost index 27.3% lower than Key Biscayne, FL. This is a broad model comparison, not a survey of today's prices or a forecast of your household spending. Some cities use adjusted regional fallback data.

What does the equivalent salary mean?

At a $150,000 salary in Key Biscayne, FL, the model estimates $126,469 in Mountain Brook, AL. It allocates 60% of gross income to the origin city’s category budget and applies each destination category’s relative cost. The equivalent salary adds the total category difference to your income. The monthly difference is the same category difference divided by 12; it is not take-home pay or guaranteed savings. Household size, childcare and your actual lease are not inputs to this calculation.

What rent estimates are available for Key Biscayne, FL and Mountain Brook, AL?

The modeled two-bedroom rents are $3,450/month in Key Biscayne, FL and $1,900/month in Mountain Brook, AL. Where available, the source is a city median of HUD FY2026 ZIP-level estimates; otherwise a saved metro table is used. City adjustments may also apply. These are not asking rents or available listings. Compare actual properties with the same bedroom count and included utilities.

How should I use this comparison before moving?

Use it to shortlist locations, then replace modeled costs with a current housing quote, employer-confirmed income, commute costs, insurance and your household's other expenses. Add one-time moving costs separately. Source years differ and the saved datasets are not a live price feed. Read the methodology for the formulas and fallback rules.

💰 See how taxes change too — compare take-home pay between Florida and Alabama on TaxTakeHome.com