Flood Zone A vs AE: What's the Difference?

The Short Answer

Zone A and Zone AE are both high-risk FEMA flood zones inside the Special Flood Hazard Area. Both carry a 1% annual chance of flooding (the 100-year floodplain). Both require flood insurance on mortgages from federally regulated or insured lenders and on federally backed loans. The fundamental flood risk is the same.

The difference is precision of information. Zone AE has Base Flood Elevations determined — FEMA has conducted detailed hydraulic engineering analysis to calculate exactly how high floodwaters will rise at specific locations. Zone A does not — FEMA has identified the area as high-risk but hasn't done the detailed study needed to establish BFEs.

Side-by-Side Comparison

Why Base Flood Elevation Matters

The BFE is the calculated water surface elevation during the 1% annual chance flood at a specific location. It appears on Flood Insurance Rate Maps as a contour line with an elevation in feet above sea level (or sometimes above NAVD 88 datum).

For Zone AE properties, the BFE is central to three things:

Insurance requirements. Both Zone A and Zone AE are high-risk zones, so a mortgage from a federally regulated or insured lender, or a federally backed loan such as FHA, VA, Fannie Mae or Freddie Mac requires flood insurance in either. Since Risk Rating 2.0, the premium itself is rated on the building’s own flood risk, including its first-floor height, rather than on the flood zone.

Building requirements. New construction and substantial improvements in Zone AE must have the lowest floor at or above the BFE (plus a freeboard that many communities require — often one foot above BFE). In Zone A without a BFE, communities must still require elevation but have more flexibility in how to determine the required elevation.

LOMA eligibility. To get a Letter of Map Amendment removing your property from the SFHA, the key showing is that your land is at or above the BFE. In Zone AE, the BFE is right there on the map. In Zone A, a hydraulic study may be needed to establish what the BFE would be.

Insurance Implications

Under Risk Rating 2.0, Zone A and Zone AE properties are priced the same way: on the building’s own flood risk, including its elevation, rather than on the zone. An Elevation Certificate is optional; in either zone you can submit one if it shows your lowest floor is higher than the data FEMA would otherwise use, which can lower the premium. Ask your agent before paying for one.

The BFE still matters in other ways: in Zone AE it is the published standard for building requirements and for a Letter of Map Amendment, while in Zone A that elevation may have to be established first.

FEMA no longer offers the Preferred Risk Policy in any zone; it was discontinued with Risk Rating 2.0. See FEMA’s Risk Rating 2.0 page.

How to Check Which Zone You're In

Use our address lookup to see your property's exact flood zone designation. The FEMA National Flood Hazard Layer data will tell you whether you're in Zone A, Zone AE, or any other designation.

If you're in Zone AE, your Flood Insurance Rate Map will show BFE contour lines. You can use FEMA's Map Service Center to view your FIRM panel and identify the BFE at your property location.

If you're in Zone A and want to know what a BFE would be for your property (for LOMA purposes or insurance rating), a licensed surveyor or civil engineer can conduct an analysis. Some Zone A areas have approximate BFEs in the FEMA study — it's worth checking before commissioning new work.

Learn more about each zone: Zone A | Zone AE

What the BFE number itself means, and how to read it: What is base flood elevation?

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