Flood zone X is the zone most US homes are in. Here is what it means, how shaded and unshaded X differ, and when flood insurance makes sense. Paste an address below to see its FEMA flood zone, or a whole list to check them all at once.
Quick answer
Flood zone X is an area of moderate or minimal flood risk on FEMA's flood maps: it is outside the Special Flood Hazard Area, the 1% annual chance ("100-year") floodplain. Shaded zone X (the old zone B, sometimes labelled X500) is moderate risk: inside the 0.2% annual chance ("500-year") floodplain, or protected by a levee. Unshaded zone X (the old zone C) is minimal risk. Flood insurance isn't required by federal law in zone X, but it is available, and often cheaper than in high-risk zones.
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Shaded zone X marks moderate flood hazard: land between the 1% and 0.2% annual chance floodplains, land where the 1% annual chance flood is less than a foot deep or drains less than one square mile, and land a levee protects from the 1% annual chance flood. Unshaded zone X is everything above the 0.2% annual chance flood level. Older maps call these zones B and C, and some digital maps label shaded X as X500.
Federal law doesn't require it: the mandatory purchase rule applies only in high-risk zones (A and V) for mortgages from federally regulated or insured lenders. A lender can still ask for it. FEMA says more than 20% of flood insurance claims come from outside the high-risk zones, often after heavy rain overwhelms local drainage, so many zone X owners buy a policy anyway.
Zone X is the lowest-risk category on most maps, so for buying a home it is the good result. It doesn't mean a property can't flood: FEMA maps rivers and coasts, not every storm drain, and maps age as areas develop. Since Risk Rating 2.0, flood insurance prices each property on its own risk (distance to water, elevation, the cost to rebuild), so a zone X home near a creek can cost more to insure than one on a hill.
Zone AE is inside the high-risk floodplain, with a base flood elevation set by detailed study: flood insurance is required there with a federally backed mortgage, and new buildings must be raised to the base flood elevation. Zone X is outside it, with neither requirement.
A guide and a planning check, not an official flood zone determination: a lender's determination, or FEMA's own map, is the official answer for a single property.
What does flood zone X mean?
It means the property is outside FEMA's high-risk floodplain. Shaded zone X is moderate risk (inside the 500-year floodplain, or behind a levee); unshaded zone X is minimal risk.
Does flood zone X require flood insurance?
Not by federal law. Flood insurance is required only in high-risk zones (those starting with A or V) for mortgages from federally regulated or insured lenders, though any lender can ask for it.
Is flood zone X good or bad?
It's the lower-risk result: outside the 100-year floodplain. It isn't a guarantee: more than 20% of flood insurance claims come from outside high-risk zones.
What is the difference between shaded and unshaded zone X?
Shaded X is moderate risk: between the 100-year and 500-year floodplains, shallow flooding under a foot, or behind a levee. Unshaded X is minimal risk: above the 500-year flood level.
What is flood zone X500?
An older label for shaded zone X: the 0.2% annual chance (500-year) floodplain, a moderate flood hazard.
What were zones B and C?
FEMA's older names. Zone B became shaded zone X (moderate risk) and zone C became unshaded zone X (minimal risk). Some older maps still show them.
How do I find out if my house is in zone X?
Enter the address in the checker above. It looks the address up in FEMA's National Flood Hazard Layer and shows the zone. For an official determination, a lender orders a flood zone determination, or you can view FEMA's Flood Map Service Center.