What does BFE mean?
In FEMA's words, the BFE is “the elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level” in a given year. That 1-percent-annual-chance flood is also called the base flood or the 100-year flood — not because it happens once a century, but because it has a 1-in-100 odds of occurring in any single year. The BFE tells you how high that water is expected to stand at your location; the flood zone tells you what kind of hazard it is.
What is BFE measured from?
A BFE is an elevation, so it is stated relative to a vertical reference — today almost always the North American Vertical Datum of 1988 (NAVD88); older maps used NGVD29. A BFE of “9 feet NAVD88” means floodwater is expected to reach 9 feet above that datum, not 9 feet above your yard. To compare it to your house you need your property's ground and floor elevations in the same datum, which is what an Elevation Certificate from a licensed surveyor provides.
BFE — how high the base flood reaches · Lowest floor elevation — how high your building sits · Freeboard — the margin between them. Positive freeboard (floor above BFE) is safer and cheaper to insure.
How is freeboard calculated against the BFE?
Freeboard = lowest floor elevation − BFE. If your lowest floor is at 11 feet NAVD88 and the BFE is 9 feet, you have +2 feet of freeboard. Many communities require 1–2 feet of freeboard above the BFE as a safety margin, and the National Flood Insurance Program rewards freeboard with lower premiums. In a VE zone the reference point is stricter: it is the bottom of the lowest horizontal structural member, not the floor surface, that must meet or exceed the BFE.
Which flood zones show a BFE?
| Zone | BFE shown? | Notes |
|---|---|---|
| AE | Yes | Detailed study; floor at or above BFE |
| VE | Yes | Coastal high hazard; structural member at or above BFE |
| A | No | Approximate study; no BFE determined |
| V | No | Velocity hazard; no BFE determined |
| X | No | Moderate / minimal hazard, outside the SFHA |
BFE definition: FEMA, Base Flood Elevation (updated Mar 5, 2020). Special Flood Hazard Area and zone labels: FEMA, Flood Zones glossary (updated Jul 8, 2020). Elevation datum (NAVD88) and Elevation Certificate practice per FEMA NFIP guidance.
How do I find the BFE for my address?
Read it off your community's effective Flood Insurance Rate Map — see how to read a FEMA flood map. The BFE is a static design number; it does not account for how far the shoreline has already moved or how high a surge may actually run in a given storm. For the moving shoreline, see the New York South Shore erosion map and the California coast; for a live event, the storm-surge watch.
How much freeboard does your address really have?
A parcel screening compares your ground elevation to the FEMA BFE, then layers on the long-term erosion rate and storm-surge exposure — the full picture, from the federal record.
Check your address · $99Frequently asked questions
What does BFE stand for?
BFE stands for Base Flood Elevation — the surface-water height of the base flood, the flood with a 1-percent chance of occurring in any given year.
Is the BFE the same as the 100-year flood level?
Yes. The base flood is the 1-percent-annual-chance (100-year) flood, and the BFE is the elevation that flood is expected to reach at a given location.
What is freeboard?
Freeboard is the vertical distance between a building's lowest floor and the BFE. Building above the BFE gives positive freeboard, which reduces flood risk and usually lowers insurance premiums.
What datum is the BFE measured in?
On current maps, the BFE is referenced to the North American Vertical Datum of 1988 (NAVD88). Older maps used NGVD29. Compare it to your property only in the same datum.
Find your BFE, zone, and panel on the FIRM.
Where the BFE reference is the structural member, not the floor.
Both show a BFE — the difference is wave energy.
How fast the coast itself is moving toward you.