Texas · Central Time
621 Area Code
Area code 621 is in Texas, serving greater Houston, including Harris County and surrounding suburbs in southeast Texas. It is in the Central Time zone. It shares its territory with overlay codes 281, 346, 713 and 832, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 621 area code?
621 is a Texas area code covering greater Houston, including Harris County and surrounding suburbs in southeast Texas. In the wider directory it sits in the South region.
Cities in the 621 area code
- Houston
- Pasadena
- Pearland
- Sugar Land
- League City
- Baytown
- Missouri City
- Katy
- Humble
- Friendswood
- Tomball
- Stafford
- Bellaire
Counties served by 621
Harris County, Fort Bend County, Montgomery County, Brazoria County, Galveston County and Waller County.
Time zone note: Almost all of Texas is Central; far-west El Paso is Mountain.
621 overlay codes and dialing
The 621 territory is covered by an overlay of 5 area codes: 281, 346, 621, 713, 832. All of them serve the same geographic area, and the original code is 713. Because more than one code covers the same ground, 10-digit dialing is mandatory — you must dial the area code for every local call. New phone lines may be assigned any of these codes.
History of the 621 area code
621 went into service on January 23, 2025 as an overlay of 346, relieving number exhaustion in the Houston area. Rather than splitting the region, the overlay lets existing customers keep their numbers while new lines draw from the added code. Learn more in our overlay guide.
Is 621 a scam or spam risk?
621 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 621 number on your screen is no guarantee the caller is in Houston, TX or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Other Texas area codes
Explore more
See every code in Texas, compare codes across the South region, or view all Central Time codes. You can also browse the 6XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
621 area code FAQ
Where is the 621 area code?
The 621 area code is in Texas, covering greater Houston, including Harris County and surrounding suburbs in southeast Texas, in the South region.
What cities are in the 621 area code?
Cities in the 621 area code include Houston, Pasadena, Pearland, Sugar Land, League City, Baytown, Missouri City, Katy, Humble and Friendswood.
What time zone is 621 in?
621 is in the Central Time zone. Almost all of Texas is Central; far-west El Paso is Mountain.
What is the overlay for the 621 area code?
621 shares its territory with 281, 346, 713 and 832. All 5 codes (281, 346, 621, 713, 832) serve the same area, so 10-digit dialing is required for every call.
When did the 621 area code start?
621 went into service on January 23, 2025 as an overlay of 346.
Do I have to dial 10 digits for 621?
Yes. Because 621 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 621 a toll-free or premium code?
No. 621 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.