How we calculate flood insurance costs

The data

Everything on this site comes from FEMA's open data platform, OpenFEMA, retrieved through its API on October 15, 2026:

• NFIP Redacted Policies, version 3 (74,739,461 records, all NFIP policy transactions since 2009; FEMA last updated it on September 9, 2026). API: https://www.fema.gov/api/open/v3/NfipPolicies.
• NFIP Redacted Claims, version 3 (2,725,989 claims since 1978; updated September 9, 2026). API: https://www.fema.gov/api/open/v3/NfipClaims.
• NFIP Residential Penetration Rates, version 1 (share of homes with NFIP flood insurance, by county; updated August 4, 2026).

FEMA removes names, street addresses and exact locations before publishing these files. The older "FIMA NFIP" version 2 datasets were retired on October 15, 2026; this site uses the current versions above.

Which policies we count

A policy is counted if it was in force on August 31, 2026: it started on or before that day, it had not expired, and it had not been cancelled by then. In practice we take the policies whose current term started between September 1, 2025 and August 31, 2026. In FEMA's data, practically every home policy in force on that date started in that window (home policies run for one year). A small number of multi-year condominium association policies (about 0.7% of all policies) started earlier and are not counted, so the "all policies" and "type of building" figures slightly undercount whole-building policies; figures for homes are not affected. Records with a zero or negative cost (refunds and rewrites) are left out. For the year-on-year comparison we repeat the same steps for August 31, 2025.

What "cost" means

We use FEMA's policyCost field: "calculated in dollars by adding together calculated premium, reserve fund assessment, federal policy fee, and HFIAA surcharge" (FEMA data dictionary). It is the total yearly amount on the policyholder's bill. FEMA's premium costs page lists those charges: a reserve fund assessment of 18% of the discounted premium, an HFIAA surcharge of $25 for primary residences and $250 for other occupancies, and a federal policy fee of $47 for most policies. Each policy counts once, whatever its coverage.

Homes and other buildings

The headline figure on every page is for homes: single-family homes, buildings with 2 to 4 units, manufactured (mobile) homes and single condo or apartment units (FEMA occupancy codes 11, 12, 14 and 16). Policies on whole buildings with 5 or more units, condominium association policies and non-residential buildings cost much more and would distort the figure, so they appear only in the "type of building" table.

Medians, percentiles and averages

The median is the middle value: half of the policies cost less, half more. The middle half runs from the 25th to the 75th percentile (linear interpolation). The average (mean) is pulled up by a minority of expensive policies, so it is usually higher than the median. All amounts are rounded to the nearest dollar.

Places and flood zones

• State: the property state in FEMA's record.
• County: the first five digits of the census block group code in the record (state and county FIPS codes); county names from the U.S. Census Bureau. A county has its own page when it has at least 100 home policies in force.
• ZIP code: the first five digits of the ZIP code reported by the insurer. A ZIP code has its own page when it has at least 300 home policies in force; smaller ZIP codes (with at least 10 home policies) appear in the search with their median.
• Flood zone: the zone used to rate the policy (ratedFloodZone), grouped as AE (AE, A1–A30), VE (VE, V, V1–V30), A, AO (AO, AOB), AH (AH, AHB), A99/AR, X (X, B, C) and D.

Claims

Claims are counted by year of loss, from 1978, where the insured property is: state and ZIP code as reported, county from the census block group code (or FEMA's county code when the block group is missing). A claim is "paid" when the building, contents and Increased Cost of Compliance payments add up to more than zero. Amounts are in dollars of the time, not adjusted for inflation.

Privacy and small numbers

We never publish a single policy or claim. Any group with fewer than 10 policies (or claims) is not shown, neither its count nor its amounts, and we do not publish minimum or maximum values.

Limits

• Not a quote. These are prices other policyholders paid. A price for your building depends on its elevation, foundation, replacement cost, the coverage and deductible you choose and more (FEMA FloodSmart: premium costs).
• NFIP only. Private flood insurance is not in FEMA's data and is not included.
• Who buys matters. Most policies in high-risk zones are bought because a lender requires them; in zone X they are often voluntary. Medians describe the people who bought, not every building.
• Yearly increase caps. FEMA explains that for most policyholders the premium "cannot increase more than 18–25% per year", and that this "usually does not apply to new policies" (FloodSmart: premium costs, checked October 15, 2026). A long-time policyholder may still be moving toward the full-risk price, so two similar homes can pay different amounts.
• Reporting delays. FEMA updates the data monthly; insurers can report changes late, so recent months can move slightly at the next update.
• Geography. ZIP codes and counties are taken from FEMA's records as reported; a few records have a missing or wrong code and are counted only in the state and national figures.

Updates

We refresh the data every month after FEMA's update. This edition: policies in force on August 31, 2026, data retrieved October 15, 2026, pages built October 15, 2026.

Check any number

Each page has links to the OpenFEMA API with the filter for that area, so you can download the same records and recompute the figures. Spotted a problem? Tell us.

This product uses the Federal Emergency Management Agency’s OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).