Runway releases Gen-4.5

Background

A text-to-video model takes a written prompt and returns a video clip. Because judging generated video is partly subjective, the field leans heavily on leaderboards. Many of them use Elo ratings, a scheme borrowed from chess: systems are compared in pairs, voters pick the better output, and each win or loss moves a rating up or down. One number then stands in for a large number of pairwise comparisons. That makes a ranking easy to read, but the score depends on which comparisons were run and who did the voting, and scores from different leaderboards are not directly comparable.

What happened

On 1 December 2025, Runway released Gen-4.5 ^[1]. On release, the model took the top position on the Artificial Analysis Text-to-Video leaderboard with a rating of 1,247 Elo ^[1].

Key details

Runway described the release as an improvement in three areas: physics, scene composition and character expression ^[1]. In generated video, physics refers to whether motion behaves the way a viewer expects — objects have weight, collisions read correctly, something thrown comes back down. Scene composition is about how subjects, background and camera framing are arranged inside a shot, and whether the arrangement a prompt describes survives into the output. Character expression covers faces and body language, the part of a shot that carries emotion.

According to Runway, the model was developed entirely on NVIDIA GPUs ^[1]. Gen-4.5 was also included in all paid plans, so subscribers on any paid tier could use it, rather than the model being held back for a single top tier ^[1].

Runway said the model set new standards for dynamic action generation, temporal consistency and controllability ^[2]. Temporal consistency means a subject keeps its appearance and identity from frame to frame, without flicker or drift in the background. Controllability means the user can direct what the model produces, instead of only writing a description and accepting the result. Dynamic action generation concerns movement itself: fast motion, several changes happening in the same shot.

The company also said it would bring existing controls to Gen-4.5 after launch ^[2]. That wording indicates the launch version did not yet carry every control Runway's video tools had offered, and that these would follow.

Why it matters

The release is a data point in the competition between video generation models. A place at the top of a public leaderboard is a claim others can check and try to beat, and a rating of 1,247 Elo gives later releases a number to be measured against on that same board.

Distribution matters as much as the score. Putting the model in all paid plans means it reaches people who already subscribe, instead of being limited to a narrow group at launch ^[1].

The hardware detail points at something else: as Runway describes it, development ran entirely on NVIDIA GPUs, which makes the model's release also a statement about the computing hardware such systems are built on ^[1].