Narrative:

We were holding short of runway xxl at ZZZ; ready for takeoff; when tower said; 'I have a 'slight' reroute for you; advise when ready to copy.' we copied the route; loaded it in the FMC; verified the route; took a quick glance at the fuel and took off. Once we leveled off at our final cruising altitude of FL370; it became readily apparent that the reroute took us several hundred miles out of the way and we may [now] be landing below our required minimum fuel due to possible weather deviations. I noted that the weather at ZZZ1 was VFR and contacted dispatch via crew cell. We agreed the weather was acceptable and removed jfk as the alternate allowing us to land with the required fuel minimums. As it turned out; we did land with the required fuel including jfk as an alternate; albeit not with; in my opinion; an acceptable margin of safety. 6.4 [was] required [and we] landed with [approximately] 6.6.expectation bias played a huge role here along with being ready to take the active when we were given this 'slight' reroute. A 'slight' reroute suggests an additional fix; maybe two - not the extensive reroute we were given. [This reroute was a] significant change.to mitigate this happening again; I need to remind myself that ZZZ during july and august is a huge thunderstorm magnet and reroutes are common. And as a captain; I set the pace and am completely responsible for the safe operation of the aircraft. I should have taken the time to taxi to a place where; after loading and verifying the route; I could call dispatch; verify the route in detail; and possibly return to the gate for additional contingency fuel.

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Original NASA ASRS Text

Title: A321 Captain reported accepting a reroute just before takeoff that resulted in a marginal fuel situation at destination.

Narrative: We were holding short of Runway XXL at ZZZ; ready for takeoff; when Tower said; 'I have a 'slight' reroute for you; advise when ready to copy.' We copied the route; loaded it in the FMC; verified the route; took a quick glance at the fuel and took off. Once we leveled off at our final cruising altitude of FL370; it became readily apparent that the reroute took us several hundred miles out of the way and we may [now] be landing below our required minimum fuel due to possible weather deviations. I noted that the weather at ZZZ1 was VFR and contacted Dispatch via crew cell. We agreed the weather was acceptable and removed JFK as the alternate allowing us to land with the required fuel minimums. As it turned out; we did land with the required fuel including JFK as an alternate; albeit not with; in my opinion; an acceptable margin of safety. 6.4 [was] required [and we] landed with [approximately] 6.6.Expectation bias played a huge role here along with being ready to take the active when we were given this 'slight' reroute. A 'slight' reroute suggests an additional fix; maybe two - not the extensive reroute we were given. [This reroute was a] significant change.To mitigate this happening again; I need to remind myself that ZZZ during July and August is a huge thunderstorm magnet and reroutes are common. And as a Captain; I set the pace and am completely responsible for the safe operation of the aircraft. I should have taken the time to taxi to a place where; after loading and verifying the route; I could call Dispatch; verify the route in detail; and possibly return to the gate for additional contingency fuel.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.