Base Flood Elevation (BFE) is the elevation of the floodplain during a 100 year flood.

Risk, FEMA Flood Zones, and Insurance Premiums

This article is written to aid property owners regarding their flood risk. Floodplain Managers, flood insurance professionals, surveyors, etc. may note that this information is high-level and not every variable is covered. Even so, it is hoped this information helps those not directly involved in the industry understand the basic terms and how they relate to flood risk and flood insurance rates.

The FEMA 100 year flood zone explained.

I use the term “100-year flood zone daily for elevation certificates, LOMA’s, and explaining flood maps.  But it doesn't mean what you might think.  It means there is a 1% chance you will see a flood like the one on the FEMA flood map each and every year.  Since 1% is also "1 out of 100", the term "100-year flood" was adopted because that's easier to talk about than rattling off a bunch of statistics.


FEMA sometimes shows a 500-year flood on their maps and that is technically the 0.2% annual chance flood.  Try saying "zero point two percent annual chance flood zone" two dozen times a day and you can see why we use the short version.


Where does the Base Flood Elevation (BFE) come from?

FEMA defines the Base Flood Elevation (BFE) as the computed elevation to which the flood is anticipated to rise during the base flood.  The base flood is also referred to as the 1-percent annual chance flood or 100-year flood.  Just in case those terms are new to you, the 1-percent annual chance flood means that, statistically, there's a 1% chance every year that there will be a flood that looks like the one on the FEMA maps.  But it could flood less, or more, or many times a year, or not at all.  The Base Flood Elevation is a baseline pulled together from historic weather data, local topography, and the best science available at the time.