Tools

Flood insurance coverage gap calculator

See how much of your home and belongings a National Flood Insurance Program policy can cover, what is left over, and when a new policy would start.

Runs entirely in your browser: nothing you enter is sent or stored by this site. Results are estimates for planning, not a quote or advice.

A homeowners policy excludes flood, and the standard answer, a policy from the National Flood Insurance Program, has dollar ceilings that a larger home or a well-furnished one can exceed. The calculator sets your rebuild cost and belongings against those ceilings, shows the shortfall you would have to fill with excess or private flood coverage, and counts 30 days forward to the day a new policy would start.

How to use it

  • Cost to rebuild. Use your dwelling limit, your insurer's replacement cost estimate or the home replacement cost estimator. Market value and the mortgage balance are the wrong numbers.
  • Your belongings. A total from the home inventory builder beats a guess. Contents are a separate coverage that you choose to buy.
  • Basement box. Tick it if much of what you own sits below ground level.
  • Day you would buy. The date you would apply and pay. It starts at today's date, so check it.
  • Mortgage box. Tick it if you have a loan and the home is in a high-risk zone (special flood hazard area), then enter the balance from your mortgage statement.

How the math works

The building gap is your rebuild cost minus $250,000, and the contents gap is your belongings minus $100,000, each floored at zero. The headline number adds the two. "NFIP could cover" is the smaller of each value and its ceiling, added together. The start date is your purchase date plus 30 days. For a lender, the required amount is the smallest of the loan balance, $250,000 and the rebuild cost.

Say, hypothetically, a $380,000 rebuild cost, $120,000 of belongings and a $250,000 mortgage, which are the tool's starting numbers. The building gap is $130,000 and the contents gap is $20,000, so $150,000 sits above the NFIP limits and the program could cover $350,000. A lender would require $250,000. Apply and pay on June 1 and the policy takes effect July 1.

What it assumes

The $250,000 building and $100,000 contents ceilings are the Regular Program limits for a single-family home in FEMA's NFIP Flood Insurance Manual (October 2025 edition) and 42 U.S.C. 4013(b); no change was found as of October 2026. The 30-day wait follows 44 CFR 61.11(d). The lender rule is a simplification: 12 CFR 22.3 sets the floor at the lesser of the unpaid balance or the maximum NFIP coverage, and FEMA's lender guidelines add the building's insurable value, which the tool approximates with your rebuild cost. The rebuild cost, belongings and balance are editable examples.

Where it stops being right

The ceilings are not the same as payouts. On a principal residence, the standard flood policy pays building losses at replacement cost only if you are insured for at least 80% of replacement cost or the maximum available, and contents are paid at actual cash value (44 CFR Part 61, Appendix A(1)%20to%20Part%2061), Article VII). The tool does not model that, and it leaves out the $30,000 of increased cost of compliance coverage, which is paid on top of building coverage but cannot push the total past the statutory maximum. Basement coverage is limited to a short list of items, covered in what flood insurance covers in a basement.

Emergency Program communities have lower limits, and condo, renter and multifamily policies differ. The tool does not show the waiting period's exceptions: coverage bought in connection with a loan closing, a one-day wait after certain map revisions, and some post-wildfire cases (the 30-day flood insurance waiting period). New policies also depend on the program being authorized. It runs through December 11, 2026 as of this writing, and lapses in late 2025 and early 2026 paused new policies while they lasted (NFIP reauthorization and what a lapse means for you). Private flood policies have their own limits and waiting periods; see Private flood insurance vs the NFIP. Nothing here is a quote.

Last reviewed October 10, 2026

Related guides

Does homeowners insurance cover flooding? No. A standard homeowners policy excludes flood, surface water and storm surge. Flood coverage takes a separate NFIP or private flood policy. NFIP flood insurance explained How the National Flood Insurance Program works: who sells it, what it covers (up to $250,000 building, $100,000 contents), what it excludes, and how it pays. Excess flood insurance above NFIP limits Excess flood insurance is a private layer above the NFIP's $250,000 building limit. How it attaches, who needs it, what to ask and where gaps can remain. Private flood insurance vs the NFIP How private flood policies differ from the federal NFIP on limits, living expenses, waiting periods, price and lender rules, and when each one tends to fit. The 30-day flood insurance waiting period A new NFIP flood policy starts 30 days after you apply and pay, with exceptions for loan closings, new map zones and post-wildfire floods. How it is counted. What flood insurance covers in a basement NFIP flood insurance covers only a short list of basement items, like the furnace, sump pump and unfinished drywall. What is excluded and how to fill the gaps.

Terms used here

National Flood Insurance Program (NFIP) The federal program, run by FEMA since 1968, that makes flood insurance available to owners and renters in communities that adopt floodplain management rules. Excess flood insurance Extra flood coverage that sits above a primary flood policy, usually the NFIP maximum, to pay for losses beyond the first policy's limits. Private flood insurance Flood coverage issued on an insurer's own form and rates instead of through the federal program, which a lender may accept in place of an NFIP policy. Increased cost of compliance (ICC) Flood policy coverage of up to $30,000, apart from the damage claim, toward elevating, relocating or demolishing a substantially damaged building. Special flood hazard area (SFHA) The land FEMA maps as having at least a 1% chance of flooding in any year, where lenders must require flood insurance on federally backed mortgages. Flood exclusion The standard homeowners provision that excludes flood, surface water, tides and overflowing water bodies, leaving flood damage to a separate flood policy.

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