The Runway Gen family
Runway own video line has two members on its API list today: Gen-4.5 at twelve credits a second and Gen-4 Turbo at five. The second is called Turbo, but what actually separates them is not speed.
- two members on the API list
- $0.12 against $0.05
- Turbo takes images only
Last checked: This is a reference page. It is re-checked against the vendor sources and updated when a new version ships. What changed
Which one to use
Gen-4.5, unless your input is always an image and your budget is tight. In that case Gen-4 Turbo does the same job at under half the price.
The difference the model name hides
On Runway own model list, Gen-4.5 accepts text or image input and Gen-4 Turbo accepts image only. So you cannot make a video from a text prompt with Turbo; you have to supply the first frame yourself.
Turbo therefore does not mean here what it means in the rest of the industry. It is not a speed tier, it is a model with one fewer input route and a price to match. Anyone choosing on price alone and then sending a text prompt runs into an error.
What this page does not have, and why
There is no timeline for this family here. Runway publishes no changelog for the line and no page says what Gen-4.5 added over Gen-4. Its documentation is a model list and a price list, and both describe the present rather than the past. We are not filling that gap from memory or from what other people have written.
The contrast with ByteDance is instructive: there the release date lives inside the model id and a five year timeline can be read off the id list. Here the id is gen4.5 and it carries no date at all.
Where this family sits in our table
Last. Gen-4.5 scores lowest in the video ranking, because its resolution ceiling is 720p, it has no audio parameter and no reference-input ceiling is published. Yet the same model is the cheapest video on Runway list, and our ranking does not measure price. Those two statements do not contradict each other and both are written on the category page.
Release timeline
Each version with its own release date, and what changed against the one before it.
- Runway Gen-4.5 current On Runway own model list, Gen-4.5 sits next to Seedance 2.5 and Veo 3.1: its maker resells the competing models on the same API.
Where it falls short
- Gen-4 Turbo cannot make a video from a text prompt and takes image input only.
- This family resolution ceiling is 720p, the lowest of the four candidates in our table.
- Runway publishes no changelog for this line, so no version timeline is written here.
- No reference-input ceiling is published, and that alone costs this model twenty points in the table.
Our take
If you are working on the Runway API and want cheap short video, this family makes sense and Turbo is the cheapest route on the entire list. If output quality is your main criterion, the same API sells better models from other vendors.