Widest payload fairing

As of 24 Jan 2022, the widest payload fairings available on operational rockets were the 5.4-m (17-ft 8-in) diameter fairings found on the Airbus Ariane 5 (European Union) and the United Launch Alliance Atlas V 500-series (USA). These fairings both have an internal diameter of 4.57 m (15 ft).

The SpaceX Starship will have a larger, 9-m-diameter fairing, but it is still in the prototype stage, and isn't scheduled to make an orbital flight until later in 2022. Plans for the Space Launch System Block 2 Cargo variant include a possible 10-m fairing, however, funding has not yet been made available for the Block 2 version of the SLS, so it is not clear when (if ever) this option might become reality.