As of January 1, 2025, the U.S. refining capacity has remained largely stable, totaling 18.4 million barrels per calendar day (b/cd). This figure is nearly unchanged compared to the previous year, according to the latest Refinery Capacity Report. The report highlights two primary measures of refinery capacity: barrels per calendar day and barrels per stream day.
Calendar day capacity estimates the input volume that a distillation unit can process over 24 hours under normal operating conditions, taking into account maintenance activities. The reported figures may vary slightly from other sources due to different estimation methods. On the other hand, stream day capacity represents the maximum amount a facility can process within a day while running at full capacity, typically exceeding calendar day capacity by around 6%.
In 2025, the largest U.S. refiners—Marathon, Valero, and ExxonMobil—reported marginal increases in calendar day capacity of less than 1% from 2024. These slight changes are attributed to minor process improvements rather than significant expansions, contrasting with previous years that saw major projects. Notably, there were no significant refinery expansions or transactions between January 2024 and January 2025.
Motiva’s Port Arthur refinery reclaimed its title as the largest U.S. refinery based on barrels per calendar day, though its stream day capacity remained stable. Conversely, Marathon’s Galveston Bay refinery remains the largest on a barrels-per-stream-day basis. Additionally, LyondellBasell ceased refining operations at its Houston facility in March 2025, but this change is not reflected in the report since the plant was operational as of January 1.
The 2025 report includes 132 operable refineries, unchanged from 2024, and notes the addition of Pasadena Performance Products, which focuses on producing alkylate rather than refining crude oil.