Runway Gen-4 API: Pricing, Specs, and How to Access It
Runway Gen-4 turns an image into a 5–10s 720p video. Plans run $12–$76/mo; the API bills Gen-4 Turbo at $0.05 per second. Full 2026 pricing and specs.
Runway Gen-4 is the AI video generator Runway released on March 31, 2025. Give it one input image and a text prompt and it returns a 5- or 10-second 720p video at 24fps, with the character and scene consistency that made it Runway's breakout model. It is no longer the newest model in the lineup (Gen-4.5 took that spot in December 2025), but Gen-4 Turbo is still the cheapest image-to-video model on Runway's API at $0.05 per second. This post covers what Gen-4 does, what it costs in credits and dollars, how to call the Runway API, and which comparable models you can call pay-per-use today.
TL;DR: Runway Gen-4 is image-to-video only: one input image plus a text prompt in, a 5- or 10-second 720p video at 24fps out. In Runway's app it costs 12 credits per second, or 5 credits per second for Gen-4 Turbo, on plans from $12 to $76 per month. On Runway's developer API a credit is a flat $0.01, so Gen-4 Turbo runs $0.05 per second and the newer Gen-4.5 runs $0.12 per second. Runway models are not available on Unifically. The closest live alternatives here are Veo 3.1, Kling 3.0, SeeDance 2.0, and Wan 2.6, all pay-per-use with no subscription.
What is Runway Gen-4?
Gen-4 launched on March 31, 2025 as Runway's flagship video model, with the faster Gen-4 Turbo following days later. Its selling point was consistency: keep the same character, object, or location across separate generations from a single reference image, with no fine-tuning. That solved the biggest complaint about AI video at the time, and it is why "runway gen 4" is still one of the most-searched video model names in 2026.
The model is strictly image-to-video. Every generation starts from a required input image that becomes the first frame, and the text prompt should describe the motion, not the scene. There is no text-to-video mode on Gen-4; that arrived with Gen-4.5.
| Spec | Gen-4 | Gen-4 Turbo |
|---|---|---|
| Input | Image (required) + text prompt | Image (required) + text prompt |
| Durations | 5 or 10 seconds | 5 or 10 seconds |
| Output resolution | 720p class | 720p class |
| Aspect ratios | 16:9 (1280×720), 9:16 (720×1280), 1:1 (960×960), 4:3 (1104×832), 3:4 (832×1104), 21:9 (1584×672) | Same six |
| Frame rate | 24fps | 24fps |
| Prompt limit | 1,000 characters | 1,000 characters |
| In-app cost | 12 credits/second | 5 credits/second |
A few things around the edges: outputs can be upscaled to 4K as a separate action in the app, a fixed seed setting reproduces similar motion across runs, and Gen-4 outputs video without sound. Audio is a separate tool in Runway's suite, not part of the generation.
The Gen-4 family also covers two related tools. Gen-4 References handles consistent characters and objects in image generation (the API model gen4_image takes reference images). Act-Two is performance capture: record yourself acting and drive a character with your movement and expression, at 5 credits per second.
Is Gen-4 still Runway's latest model?
No. Runway announced Gen-4.5 on December 1, 2025, and its help center now files Gen-4 under "an older generation" of models. At launch, Gen-4.5 topped the crowd-voted Video Arena leaderboard, ahead of Google's Veo and OpenAI's Sora 2 Pro.
The practical differences, from Runway's own spec sheets:
- Gen-4.5 does text-to-video. No input image needed, 16:9 at 720p. Image-to-video works too, across the same six aspect ratios as Gen-4.
- Flexible durations. 2 to 10 seconds, against Gen-4's fixed 5 or 10.
- Same in-app price as base Gen-4. 12 credits per second, with a Standard plan or higher required in the app.
- Better motion and prompt following. Gen-4.5 handles sequenced instructions in one prompt: camera choreography, timed events, atmosphere changes.
So why would anyone still use Gen-4? One reason: Gen-4 Turbo costs 5 credits per second, well under half of Gen-4.5's 12, and it is still the model Runway recommends for testing ideas before spending on a final pass. For video-to-video editing, Runway's current answer is Aleph 2.0 (28 credits per second on the API).
Runway Gen-4 pricing: credits and plans
Runway bills everything in credits. In the app, credits come bundled with a subscription. On the developer API, you buy them directly at $0.01 each.
The app plans, at annual-billing rates from runway.com/pricing:
| Plan | Price | Credits |
|---|---|---|
| Free | $0 | 125 one-time credits |
| Standard | $12/mo ($15 month-to-month) | 625/month |
| Pro | $28/mo ($35 month-to-month) | 2,250/month |
| Max | $76/mo ($95 month-to-month) | 9,500/month, 1-month rollover |
| Enterprise | Custom | Custom |
Max replaced the old Unlimited plan, which Runway now labels legacy. Extra credits can be bought on any paid plan, minimum 1,000 per top-up, and they do not expire.
What a single generation costs in credits:
| Generation | Credits | API price ($0.01/credit) |
|---|---|---|
| Gen-4 Turbo, 5 seconds | 25 | $0.25 |
| Gen-4 Turbo, 10 seconds | 50 | $0.50 |
| Gen-4, 5 seconds | 60 | App only |
| Gen-4, 10 seconds | 120 | App only |
| Gen-4.5, 10 seconds | 120 | $1.20 |
To make the plan math concrete: Standard's 625 monthly credits buy 25 five-second Gen-4 Turbo videos, or about 10 on base Gen-4, or 5 ten-second Gen-4.5 videos. Working backwards, a credit effectively costs about $0.019 on Standard, $0.012 on Pro, and $0.008 on Max, so the API's flat $0.01 lands between Pro and Max without a monthly commitment.
Does Runway have an API?
Yes. The developer platform lives at dev.runwayml.com, with docs at docs.dev.runwayml.com. It runs on its own credit purchases at $0.01 per credit; no subscription needed. Note that base Gen-4 is app-only. On the API, the Gen-4 route is gen4_turbo.
Runway's own models on the API:
| API model | Task | Rate |
|---|---|---|
gen4_turbo | Image-to-video | 5 credits/s ($0.05/s) |
gen4.5 | Text- and image-to-video | 12 credits/s ($0.12/s) |
act_two | Performance capture | 5 credits/s ($0.05/s) |
aleph2 | Video-to-video editing | 28 credits/s ($0.28/s) |
gen4_image | Image generation with references | 5 credits per 720p image, 8 per 1080p |
gen4_image_turbo | Fast image generation | 2 credits per image ($0.02) |
The same API also carries third-party models under Runway's credit system (Veo 3.1, SeeDance 2, Hailuo 3, ElevenLabs audio, and others), at higher per-second rates than Runway's own models.
Official SDKs are @runwayml/sdk for Node and runwayml for Python. A Gen-4 Turbo call looks like this:
from runwayml import RunwayML
client = RunwayML() # reads RUNWAYML_API_SECRET
task = client.image_to_video.create(
model="gen4_turbo",
prompt_image="https://example.com/first-frame.jpg",
prompt_text="Slow dolly-in as the subject turns toward the window",
ratio="1280:720",
duration=5,
).wait_for_task_output()
print(task.output)
Generation is asynchronous: the API returns a task, and the SDK helper polls until the video is ready. API keys are issued in the developer portal after sign-up.
Runway Gen-4 vs alternatives you can call today
Runway's models are not available on Unifically, and we are not going to pretend otherwise. To call Gen-4 or Gen-4.5, go through Runway's own API or app as described above.
If what you want is strong image-to-video billed pay-per-use, with no subscription and no credit packs, these are the closest models live on Unifically today:
- Veo 3.1: up to 8 seconds, 720p to 4K, with synchronized dialogue, ambient sound, and effects generated in the same call. From $0.075 per video. Gen-4 outputs silent video, so native audio is the clearest capability gap.
- Kling 3.0: multi-shot generation with 2 to 6 scenes per call, 3 to 15 seconds single-shot, a 4K mode, and lip-sync. From $0.06 per second.
- SeeDance 2.0: up to 9 image, video, and audio references against Gen-4's single input image, 4 to 15 seconds, up to 4K on Pro. The Mini variant starts at $0.037 per second.
- Wan 2.6: text-, image-, or reference-to-video with up to 5 references, 720p or 1080p, 2 to 15 seconds, with automatic audio. The Flash variant runs $0.0175 per second at 720p.
All four run through one API key with per-second billing and no monthly fee. New accounts start with $0.20 of free balance; on video models that covers only a couple of seconds, so treat it as a smoke test rather than a trial. Live rates for every model are on the pricing page, and the full catalog is at /models.
Frequently asked questions
How much does Runway Gen-4 cost?
In Runway's app, 12 credits per second for Gen-4 and 5 for Gen-4 Turbo, on plans from $12 to $76 per month. On Runway's API, credits cost $0.01 each, so a 10-second Gen-4 Turbo video is 50 credits, or $0.50.
Is Runway Gen-4 free?
Partly. Runway's Free plan includes 125 one-time credits, enough for five 5-second Gen-4 Turbo videos, and they do not refill monthly. After that you need a paid plan or API credits.
What is the difference between Gen-4 and Gen-4 Turbo?
Same task, same specs. Turbo generates faster and costs 5 credits per second against Gen-4's 12. Runway recommends drafting in Turbo and switching to Gen-4 only when Turbo's results fall short. The API offers only the Turbo version, as gen4_turbo.
Does Runway Gen-4 do text-to-video?
No. Gen-4 and Gen-4 Turbo require an input image that becomes the first frame; the prompt describes the motion. For text-to-video from Runway, use Gen-4.5, which generates 16:9 720p video from a prompt alone at 12 credits per second.
What resolution is Runway Gen-4?
720p class, in six aspect ratios: 1280×720, 720×1280, 960×960, 1104×832, 832×1104, and 1584×672, all at 24fps. The app can upscale a finished video to 4K as a separate step.
Can I use the Runway API without a subscription?
Yes. The developer API at dev.runwayml.com bills its own credits at $0.01 each, with no plan required. Subscriptions only cover the app at runway.com.
We will update this post when Runway changes API credit rates, when Gen-4.5's promised additional input types arrive, or if Gen-4 Turbo leaves the API. If Runway models ever come to Unifically, this comparison section is where we will say so.
