Base flood elevation (BFE) is the height floodwater is expected to reach during the base flood — the flood that has a 1% chance of being equalled or exceeded in any given year (44 CFR 59.1), the so-called “100-year flood.” It is printed on FEMA’s Flood Insurance Rate Maps in feet above a fixed reference level, a vertical datum, not above the ground. A BFE of 8 feet means floodwater reaches 8 feet above that reference level. It does not mean 8 feet of water in your yard.
Look up your address. Where FEMA’s digital flood map assigns a single BFE to your flood-zone area, the result shows it next to your zone. Along many rivers the BFE changes from place to place and is drawn as lines on the map panel instead. If your result shows no BFE in Zone AE, check the panel (see below).
Look up 1700 Convention Center Drive, Miami Beach and the result reads Zone AE, Base Flood Elevation: 8.0 ft, from FEMA map DFIRM 12086C (Miami-Dade County). FEMA’s map data records the datum for that BFE as NGVD 29.
Three things follow from that one number:
Only flood zones with detailed study have one. FEMA’s own zone definitions:
If you’re in Zone A with no BFE, the community floodplain administrator may hold other elevation data. An engineer can also determine one. See Zone A vs AE for what difference that makes.
Where FEMA has published final BFEs, communities in the National Flood Insurance Program must enforce minimum building standards keyed to them (44 CFR 60.3):
Those are the core federal minimums for homes. The regulation adds rules for non-residential buildings in A zones, which can be floodproofed instead of elevated, and for Zones AO and A. Communities may adopt stricter rules, and many require freeboard, meaning a set margin above the BFE. Your local building or floodplain office can tell you the local requirement.
Where your building sits relative to the BFE is recorded on an Elevation Certificate, a FEMA form whose elevation section must be certified by a land surveyor, engineer or architect authorized by state law to certify elevation information. It records the building’s elevations next to the BFE; communities use it to document compliance, and owners can also use it when buying flood insurance. (FEMA form and instructions)
Most A-zone claims were rated in zones where the flood map shows a BFE. Of the 1,804,748 claim records, paid or not, in FEMA’s NFIP claims file on buildings rated in A zones, 1,521,034 (84.3%) were rated in Zone AE or A1–A30. Another 202,046 (11.2%) were in Zone A, which has no BFE. Zone AH (BFE shown) accounts for 45,814 and Zone AO (depth shown) for 24,885, counting their rating-only variants AHB and AOB. The remaining 10,969 are Zone A99 (10,865) and a few other rating codes. In the coastal V zones, 89,180 of 90,463 claims were rated in VE or V1–V30.
The file also records whether each building was pre-FIRM or post-FIRM. For rating purposes, FEMA treats a building as post-FIRM if its construction or substantial improvement started after December 31, 1974, or on or after the date of the community’s first flood map, whichever is later. Post-FIRM buildings were subject to the floodplain building rules that came with the map; pre-FIRM buildings went up before those rules applied. Among all A-zone claims, including Zone A without a BFE, 74.2% (1,339,207) were on pre-FIRM buildings. For losses since 2000, the figure is still 68.1%.
One caution: these are claim counts, not rates. The file doesn’t say how many pre-FIRM and post-FIRM buildings were insured, so it can’t show how much less often a post-FIRM building floods. What it does show is that buildings that predate the flood maps still account for most A-zone claims.
Related: What is a 100-year flood?, What is a Special Flood Hazard Area?, What is the NFIP?, Buying a house in a flood zone
Sources: definitions from 44 CFR 59.1 and 60.3 and FEMA’s NFIP claims data dictionary; example from FEMA’s National Flood Hazard Layer; claims figures from FEMA OpenFEMA NFIP Redacted Claims (all records, retrieved October 2026).
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