Flood Insurance Calculator: Find Your Coverage Gap

A flood policy has hard limits, and many homes are worth more than those limits. This flood insurance calculator compares your rebuild cost and belongings with your building and contents limits, so you can see the gap you would carry yourself if a flood destroyed everything.

How to use this calculator

1. Cost to rebuild. Use the cost to rebuild the house, not its sale price. Land is not damaged by a flood and is not insured. Your homeowners policy’s dwelling limit is a reasonable starting point.
2. Value of belongings. Add up what it would cost to replace your furniture, clothing, appliances and electronics. A home inventory helps.
3. Building and contents limits. Look at the declarations page of your flood policy. If you have no flood policy, enter the limits you are considering. The defaults ($250,000 and $100,000) match the NFIP maximums for a home.
4. Deductibles. Building and contents carry separate deductibles. Enter both added together.

How this calculator works

For each part, the tool takes the smaller of your value and your limit. Anything above the limit is “uncovered.” The maximum payout is what fits inside the limits, minus the deductible.

Building covered = smaller of (Building value, Building limit)
Contents covered = smaller of (Contents value, Contents limit)
Uncovered = (Building value − Building covered) + (Contents value − Contents covered)
Maximum payout = Building covered + Contents covered − Deductible (not below $0)

The uncovered amount does not include the deductible. Your real out-of-pocket cost in a total loss would be the uncovered amount plus the deductible.

Worked examples

Example 1 (defaults, hypothetical). Rebuild cost $380,000, belongings $120,000, limits $250,000 and $100,000, deductibles $2,000.

• Building covered: smaller of $380,000 and $250,000 = $250,000
• Contents covered: smaller of $120,000 and $100,000 = $100,000
• Uncovered: ($380,000 − $250,000) + ($120,000 − $100,000) = $130,000 + $20,000 = $150,000
• Maximum payout: $250,000 + $100,000 − $2,000 = $348,000

Example 2 (lower limits chosen, hypothetical). Rebuild cost $200,000, belongings $60,000, limits $150,000 and $40,000, deductibles $1,250.

• Building covered: $150,000; contents covered: $40,000
• Uncovered: $50,000 + $20,000 = $70,000
• Maximum payout: $150,000 + $40,000 − $1,250 = $188,750

What your result means

The uncovered figure is your worst-case gap: money you would need from savings, loans or disaster aid if a flood destroyed the home. A gap of $0 means your limits match your values. Not every flood destroys a whole home. A partial loss is paid on the actual damage, still subject to the deductible and policy rules, so the gap only shows the worst case.

Rules that change the answer

• NFIP limits. For a home, building coverage goes up to $250,000 and contents up to $100,000, and valuables such as original art and furs have a $2,500 sublimit (FloodSmart).
• Contents at actual cash value. NFIP pays belongings at their value at the time of the damage, not their original or replacement cost (FloodSmart agent resources).
• Basements. FloodSmart lists personal property kept in basements among items the policy does not protect.
• Waiting period. Coverage usually starts 30 days after purchase, with some exceptions.
• Mortgage rules. Homes with government-backed mortgages in high-risk flood areas must carry flood insurance (FEMA). Check your zone on FloodSmart.

Common mistakes

• Using the home’s market value, which includes land, instead of rebuild cost.
• Buying building coverage only and assuming belongings are included.
• Forgetting that contents are paid at depreciated value.
• Keeping valuables or a finished-basement setup without checking basement exclusions.
• Assuming homeowners insurance will pay for flood damage.
• Buying a policy and never updating it after a remodel or big purchases raise the value of your home and belongings.
• Thinking a low-risk flood zone means no risk. Your lender may not require flood insurance there, but floods can still reach your home.

Limits and when to get help

This tool only compares values with limits in a total-loss case. It does not price premiums, rate your flood risk, apply depreciation or apply every NFIP exclusion. Private flood policies may work differently. Ask a licensed insurance agent or your insurer for quotes and policy details. Learn more in our guide on whether you need flood insurance, and plan for the deductible with the emergency fund calculator. This page is educational and is not insurance advice.