Runway Gen-4.5: What Runway Has Actually Published
One hard number — 1,247 Elo, on December 1, 2025. No resolution, no duration, no audio spec, no API details, no pricing.
Search for Gen-4.5's specs and you will find confident answers about resolution, clip length and control features. Runway's own announcement contains none of them. This page records exactly what Runway published, marks everything else as unverified, and dates the benchmark claim. Last verified August 7, 2026.
Runway is not in our generator
You cannot generate with any Runway model on ImagineToVideo, and we have never offered one. This page documents what Runway's own research announcement states — and, just as importantly, what it does not. Runway's models are available directly from Runway.
All sources last checked on
Specs you can actually plan around
Seedance 2.5, Kling V3, VEO 3.1 and Seedance 2.0 run on this site, and every duration and resolution limit is published.
Open the generatorWhat Runway's announcement does and does not contain
One published number: 1,247 Elo
Runway states Gen-4.5 ranked #1 on the Artificial Analysis text-to-video benchmark with 1,247 Elo. This is the only hard figure in the announcement.
No resolution stated
The announcement does not say what resolutions Gen-4.5 outputs. Any specific figure you have seen, including 4K, does not come from this page.
No duration or audio spec stated
Maximum clip length is not given, and the announcement does not describe audio generation at all.
No API details or pricing stated
The announcement is a research post, not documentation. It references image-to-video, keyframes and video-to-video as control modes, without technical specifications for any of them.
Confirmed, with the source for each line
Everything below is quoted from Runway's own research announcement. Where the announcement is silent, this page says so rather than filling the gap.
Runway announced Gen-4.5 on December 1, 2025.
The announcement is dated on the page itself. Coverage describing an earlier or later launch is not following this source.
Runway states Gen-4.5 ranked #1 on Artificial Analysis text-to-video with 1,247 Elo.
This is Runway's own wording about its own model. It was accurate on the day it was published — see the timeliness table below for where that stands now.
Runway named its comparison set: Veo 3 at 1,226, Kling 2.5 at 1,225 and Sora 2 Pro at 1,206.
Worth noting that all three of those have since been succeeded by later versions, so the comparison describes a moment rather than a current standing.
The announcement publishes no resolution, duration, audio, API or pricing details.
It describes prompt adherence, scene complexity, character expression and stylistic range in qualitative terms, and references image-to-video, keyframes and video-to-video as control modes — with no numbers attached to any of it.
Gen-4.5 first appeared on the arena anonymously as "Whisper Thunder".
The model climbed the leaderboard under that codename before Runway identified it on December 1, 2025 — the same anonymous-debut pattern Alibaba's HappyHorse followed four months later.
Claims in circulation, checked one by one
These are the Gen-4.5 details being repeated across the web. None of them appear in Runway's announcement — which is not the same as saying they are false.
| Claim in circulation | What Runway's announcement says | Verdict |
|---|---|---|
Native 4K output | ⚠️ Unconfirmed — no resolution published | |
A specific maximum clip length | ⚠️ Unconfirmed — no duration published | |
Motion brush and scene-consistency controls | ⚠️ Unconfirmed in this source Runway has shipped such controls in other products; this page only records what the Gen-4.5 announcement says. | |
Native audio added to Gen-4 in May 2026 | ⚠️ Unconfirmed — no primary source found | |
Aleph as a Gen-4.5 capability | ⚠️ Unconfirmed in this source |
Every row here is unconfirmed and not one is refuted — deliberately. Nothing on this list is contradicted by a second Runway document; the claims are simply unsourced. Marking them "false" would be the same error the pages we are correcting make, in the opposite direction.
The "number one" claim, with a timestamp
Runway's benchmark claim was accurate when published. Benchmarks move; the claim stays fixed on the page. Both facts belong together.
- Who said it, and when
- Was it right then?
- Yes — accurate on the day it was published
- As of 2026-08-07
- Gen-4.5 does not appear on the leaderboard we checked. The leader is Gemini Omni Flash at Elo 1244.
- Who said it, and when
- Was it right then?
- Yes — those were the standings at the time
- As of 2026-08-07
- All three have since been succeeded — Veo 3.1 and Kling 3.0 variants now occupy those slots.
Elo is a relative score: everyone's number moves when new models enter the arena. A model dropping off a leaderboard can also reflect that arena's coverage decisions rather than any change in the model. Check the live leaderboard rather than any figure quoted in an article — including this one.
What this means for you
If you are trying to plan a production around it
You cannot, from published information alone. Maximum clip length, output resolution and whether audio is generated are all unstated, and those are the three things a schedule and a delivery spec depend on. Runway's product surfaces will tell you what your account can do; the research announcement will not.
If you are comparing it against other models
The only published basis for comparison is a blind-preference Elo from December 2025, and preference scores say nothing about resolution, length or format. A comparison built on that number alone is comparing one axis and implying the rest.
How to check any Gen-4.5 claim yourself
Four steps. The first one settles most of them.
Open Runway's announcement
Go to the Gen-4.5 research post on runway.com and read it end to end. It is short. Note what is not in it — that absence is the answer to most spec questions people ask about this model.
Search it for a number
The only hard figures on the page are the Elo scores. If an article quotes a resolution or a clip length as though Runway published it, that number came from somewhere else.
Check today's leaderboard
Open the Artificial Analysis text-to-video leaderboard. Any "#1" claim without a date attached is describing a past state of a list that changes.
Separate silence from denial
Runway not publishing a spec does not mean the capability is missing — it means nobody outside Runway can cite it. That distinction is the whole difference between this page and a page that guesses.
Update log
Both sources are re-checked weekly. Every change lands here with its date.
Page published; benchmark claim dated against the current leaderboard
Runway's announcement was confirmed to publish one hard figure — 1,247 Elo on 2025-12-01 — and no resolution, duration, audio, API or pricing detail. Gen-4.5 no longer appears on the leaderboard checked; the leader is Gemini Omni Flash at 1244.
Runway announces Gen-4.5
Published as ranked #1 on Artificial Analysis text-to-video with 1,247 Elo, ahead of Veo 3, Kling 2.5 and Sora 2 Pro. The model had been climbing the arena anonymously as "Whisper Thunder" beforehand.
Questions people are asking about Runway Gen-4.5
When was Runway Gen-4.5 released?
Runway's research announcement is dated December 1, 2025. The model had already been climbing the Artificial Analysis arena anonymously under the codename "Whisper Thunder" before Runway identified it.
Does Gen-4.5 support 4K?
⚠️ Runway's announcement states no resolution at all — not 4K, not 1080p, nothing. Any specific resolution you have seen quoted did not come from that page. This is unverified rather than false: Runway simply has not published it.
How long can a Gen-4.5 clip be?
⚠️ Not published. No duration figure appears in Runway's announcement. If clip length matters to your plan, it is not something you can source from Runway's public research post.
Does Gen-4.5 generate audio?
⚠️ Not stated. The announcement does not discuss audio generation. We also found no primary Runway source for the widely repeated claim that native audio was added to Gen-4 in May 2026.
What is Whisper Thunder?
The codename Gen-4.5 used while competing anonymously on the Artificial Analysis Video Arena before Runway revealed it on December 1, 2025. Alibaba's HappyHorse used the same anonymous-debut playbook four months later.
Is Gen-4.5 still the number one model?
Runway's claim of #1 with 1,247 Elo was accurate on December 1, 2025. As of August 7, 2026 Gen-4.5 does not appear on the leaderboard we checked, where Gemini Omni Flash leads at 1244. Note that dropping off an arena can reflect that arena's coverage decisions rather than a change in the model.
Can I use Runway on ImagineToVideo?
No. No Runway model is in our generator and none has been. Runway's models are available directly from Runway.
Every limit on this site is published
Seedance 2.5, Kling V3, VEO 3.1 and Seedance 2.0 all run here, and their durations, resolutions and reference inputs are listed rather than left to guesswork.