Runway vs Seedance for Video Ads: Pay 2.5x per Second for 3x Longer Takes

One 30-second take, or three 10-second clips

A growth lead at a supplement brand has a 30-second Reels script and one Runway account, and she can spend its credits on either of two engines.

The first is Runway's own Gen-4.5. Runway's developer API caps a Gen-4.5 clip at 10 seconds, so her script becomes three clips joined in the edit. That's 360 credits, or $3.60 at the API's rate of a cent a credit. The second is ByteDance's Seedance 2.5, which Runway also sells. It renders all 30 seconds in one generation for 900 credits, or $9.00.

So at 720p, Seedance 2.5 costs 2.5 times as much per second as Gen-4.5, but each take can run three times as long. That's the matchup in two lines.

"Runway vs Seedance" sounds like a fight between two rivals, but it's closer to one store selling two engines for the same credits. Runway's Seedance 2.5 page says "Seedance 2.5 is available on all paid plans," and the Pro and Max cards on its pricing page list Seedance 2.5 among their models. So the real decision is which engine gets the credits for which shot.

We should say up front that Novoads competes in AI video ads and offers Seedance 2.5 too, so we have a stake in half of this comparison. Every rival price below is the vendor's own, as of September 2026.

The short answer for ad work

Neither engine wins every shot. Gen-4.5 gives you the cheaper second of video. Seedance 2.5 gives you the longer take, with sound and a deep reference budget in one pass.

Choose Gen-4.5 when

• The shot is short and visual, like a pour, a fabric drop or a product turning on a plinth. Runway sells Gen-4.5 on physics.
• You're testing lots of openings, and the cost per second decides how many you can afford.
• The ad's headed for a professional edit. Runway's API offers ProRes, PNG sequence and HDR output on Gen-4.5.

Choose Seedance 2.5 when

• The script runs past 10 seconds and a cut in the middle would hurt it, as in a spoken testimonial or a one-take demo.
• You want sound back with the picture. Runway's Seedance page says "your video comes back with visuals and sound."
• The brief leans on references, such as product shots, a style frame, a voiceover or an earlier ad. Runway's API accepts up to 30 images, 10 videos and 10 audio clips for Seedance 2.5.

For short visual shots and cheap hook tests, Gen-4.5 has the edge. For long takes with sound and heavy references, Seedance 2.5 does.

Runway sells both engines, which changes the question

The two engines came to Runway by different routes, and that explains most of the price gap.

Gen-4.5 is Runway's own model

Runway announced Gen-4.5 on December 1, 2025, and says "Gen-4.5 is available across all paid Runway plans." Its API changelog reads "February 10th, 2026 - Gen-4.5 is now available on Runway Dev," with durations of 2 to 10 seconds. The API takes text or an image and returns video.

It's also the engine Runway builds its delivery formats around. On the API, professional formats such as ProRes and PNG sequences are "Available on Gen-4.5 and Aleph 2.0," and true HDR is on Gen-4.5 alone. If you're an agency cutting in a grading suite, that matters more than a few cents a second.

Seedance 2.5 is ByteDance's model, on Runway since August

ByteDance launched Seedance 2.5 in a post dated July 31, 2026, saying it "extends single-pass video generation from 15 to 30 seconds." Runway added it to its developer platform a week later. The changelog entry reads "August 7th, 2026 - Seedance 2.5 ( seedance2_5 ) is now available on Runway Dev," and the model launched there at 480p or 720p, with 1080p added on August 15. The API accepts text, images or video as input.

Runway markets it straight at marketers. Its Seedance page promises "Up to 30 seconds in one generation" and output "at 480p, 720p and 1080p," and tells ad teams, "Go from idea to a finished ad without a shoot to book." If you want to know what the model does outside Runway, our explainer on Seedance 2.5 covers it.

Runway's shelf holds more than these two

Runway describes its lineup as "Runway models like Gen-4.5 and Aleph 2.0, plus third-party models like Nano Banana Pro 2, GPT Image 2, Kling 3.0, Kling O3, Veo 3.1, Seedance 2.5 and more." So one subscription gets you several other video engines too. Our Runway vs Kling comparison prices Kling 3.0 on the same shelf, and our Runway vs Veo comparison does the same for Veo 3.1. You can also get ByteDance's model outside Runway.

• ByteDance's own apps. The July 31 launch post said Seedance 2.5 was "rolling out on Jimeng AI, Doubao Pro, and other platforms."
• API hosts such as fal, which bill Seedance 2.5 by resolution and length.
• Ad tools that wrap the model in a script-to-ad workflow, which is what we do at Novoads.

Cost per second on Runway's meter

Runway prices both engines in credits, which makes them easy to compare. The API sells credits at a flat rate, while the web plans bundle them monthly at a different effective price.

The list rates at a cent a credit

Runway's API pricing page says "Credits can be purchased for $0.01 per credit in the developer portal for an organization." That's the rate behind the per-second prices in this table.

Engine on Runway's API	Credits per output second	Per second
Gen-4.5	12	$0.12
Seedance 2.5, 480p	20	$0.20
Seedance 2.5, 720p	30	$0.30
Seedance 2.5, 1080p	68	$0.68
Seedance 2.0, 480p or 720p	36	$0.36
Seedance 2.0 Mini, 480p or 720p	16	$0.16

At 720p, Seedance 2.5 costs 2.5 times what Gen-4.5 does per second. It's also cheaper per second on this list than Seedance 2.0 at the same resolution. Runway Academy's credits page matches, with 30 credits a second for Seedance 2.5 at 720p and 12 for Gen-4.5.

Surcharges and minimums that move the total

The headline rates leave out a few details that change an ad budget.

1. Reference video costs extra on Seedance 2.5. At 720p, Runway adds 15 credits for every second of input and reference video, and it caps the combined video at 30 seconds. Reference images and audio are free. If you add a 10-second clip of your current best ad as a reference to a 15-second take, the take goes from 450 credits to 600.
2. Each Seedance 2.5 generation has an 80-credit minimum. That doesn't change the bill for an ad-length clip, because the shortest duration the API launched with (4 seconds) already costs 80 credits at 480p and 120 at 720p.
3. An "auto" duration is billed at the maximum up front. Runway's API reference says auto "is billed at the variant maximum up front; unused credits are refunded after the generation finishes." If a batch has to fit a budget, set an explicit length.
4. Gen-4.5's delivery formats cost extra. ProRes and PNG sequences add 5 credits a second, and 10-bit and HDR profiles add 20.

What plan credits buy in Seedance 2.5

The math shifts on Runway's web plans (our Luma AI vs Runway comparison counts each plan in Gen-4.5 clips). Standard costs $15 a month for 625 credits. Runway equates that to 52 seconds of Gen-4.5, or about $0.29 a second. At the Academy's 30-credit rate, Seedance 2.5 at 720p works out to about $0.72 a second on Standard. A single 30-second take at that rate costs 900 credits, which is more than the plan gives you in a whole month.

Pro ($35 a month for 2,250 credits) and Max ($95 a month for 9,500) give you more room. Max's card also puts a "26% off" badge on its Seedance 2.5 chip, with the tooltip "26% off on 1080p generations." If you need extra credits, the minimum purchase is 1,000.

Seedance 2.5 priced off Runway

fal sells the same model per generation. For image-to-video, fal says "for 720p, you will be charged roughly $0.4730 per second of generated video," and its own worked example puts a 30-second 720p clip at about $13.87. fal bills by frame area, so a vertical 720 by 1280 clip covers the same pixels as its 1280 by 720 example and bills the same. It also notes that "wider aspect ratios have larger frame areas and cost more per second." fal doesn't bill input images, and Runway's Seedance 2.5 rate treats reference images as free. On list prices, then, Runway's API is the cheaper place to buy a second of Seedance 2.5 at 720p. If you want to turn any vendor's credit table into a cost per finished ad, our guide to AI video credits shows how.

Clip length and the cost of a join

Per-second prices only compare fairly when the clips do the same job, and once you look at length, they don't.

Gen-4.5 stops at 10 seconds a clip

On Runway's API, a Gen-4.5 duration "Must be an integer from 2 to 10." So a 15-second ad takes two clips and a 30-second spot takes three. Ten seconds is plenty for a hook, a product close-up or a B-roll insert, but you can't get one continuous take of a presenter talking through a whole script.

Seedance 2.5 runs to 30 seconds, then extends

Runway's Seedance page calls it "Native 30-second output, with high-quality extension for longer clips," and adds "Room for a full ad or scene, not just a snippet." On the API, that's a video-to-video extend mode, and ByteDance says the model "supports multiple rounds of extension."

Within one take, Runway says "Multiple scenes, camera angles and pacing shifts come out of one generation, with no separate clips to stitch together." Sound can come along too, since the API changelog describes Seedance 2.5 video "with optional generated audio." If you want to write one prompt that directs all 30 seconds, dialogue included, our Seedance 2.5 prompt guide walks through it.

Why a join costs more than it looks

Three short clips cost less to render, but every join between them has to be hidden. At each join,

• the presenter's face, hair or light can shift between clips,
• the product can change angle, size or label position,
• a spoken line has to cross a cut without a jump in the voice,
• an editor spends time making the seam invisible.

None of that matters for a 6-second hook. For a 30-second testimonial, though, it's most of the risk, and the extra 18 cents a second is what buys that risk down.

Motion: two different pitches, no shared scoreboard

Both vendors make strong motion claims, but if you read them closely, they're about different things.

Runway sells Gen-4.5 on physical accuracy

Runway's announcement says "Objects move with realistic weight, momentum and force. Liquids flow with proper dynamics," and that "fine details like hair strands and material weave remain coherent across motion and time." In an ad, that means the serum drop, the dress hem or the sneaker landing on concrete.

Runway also lists the model's limits, and one of them is object permanence, where "objects may disappear or appear unexpectedly across frames (e.g., a cup vanishing after being occluded)." In a product ad, that's the bottle that vanishes when a hand passes in front of it.

ByteDance sells Seedance 2.5 on direction across a take

ByteDance's launch post says Seedance 2.5 "delivers notable gains in image, audio, and motion quality," and that "Within 30 seconds, the model can organize multiple logically connected shots." ByteDance also says it strengthened references, "including clay render, motion, and creative references," so you can steer the camera path with a rough 3D blocking pass or a reference clip.

That's a different bet. The pitch is less about one perfect pour than about a whole sequence that holds together, with the same face, the same pack and the same room through several camera changes. These are ByteDance's own claims, though, so treat them as a brief for your test rather than a result.

The 1,247 Elo chart predates Seedance 2.5

Runway says Gen-4.5 "ranked #1 on the Artificial Analysis Text-to-Video benchmark with 1,247 Elo points," on a leaderboard dated November 30, 2025, where "Rankings are determined by blind human preference voting across thousands of pairwise comparisons." That snapshot is from eight months before ByteDance launched Seedance 2.5, so it can't tell you anything about this matchup. Realism also comes from the engine, and many ad tools rent the same engines, which is why it rarely decides a purchase. We make that case in where AI UGC realism actually comes from.

Five motion tests before you commit a batch

Render the same brief on both engines, then check each take against these tests.

1. A liquid. A drop, a pour or a spray. It's the shot Runway pitches Gen-4.5 on.
2. An occlusion. Have a hand pass in front of the product, and watch for the vanishing object Runway lists as a limit.
3. An orbit. Have the camera circle the pack. Does the label keep its shape and lettering?
4. A cut inside the take. Ask Seedance 2.5 for two angles in one generation. Is the product exactly the same after the cut?
5. A long spoken stretch. Twenty seconds of a presenter talking. Is the mouth still in sync with the voice by the end?

Go with whichever take passes, even if a different engine won last quarter. Once the survivors are running, our guide to ad creative testing covers how to read a winner without fooling yourself.

Worked example: one 30-second spot and ten hooks

Say a supplement brand needs one 30-second vertical spot at 720p, plus ten 5-second alternate openings to test in front of it. The product photo goes in as the image input (our Seedance vs Nano Banana comparison covers that still-to-clip handoff). We priced it three ways on Runway's API, before any retries.

All Seedance 2.5

• Spot: 30 seconds × 30 credits = 900 credits ($9.00), one take, sound on by default.
• Hooks: 10 × 5 seconds × 30 credits = 1,500 credits ($15.00).
• Total: 2,400 credits, or $24.00.

All Gen-4.5

• Spot: three 10-second clips, 30 seconds × 12 credits = 360 credits ($3.60), with two joins to hide.
• Hooks: 10 × 5 seconds × 12 credits = 600 credits ($6.00).
• Total: 960 credits, or $9.60.

The split

• Hooks on Gen-4.5: 600 credits ($6.00).
• Spot on Seedance 2.5: 900 credits ($9.00).
• Total: 1,500 credits, or $15.00. If you add a 10-second reference clip of your best ad to the spot, it rises by 150 credits, to $16.50.

For context, the all-Seedance brief would cost roughly $37 on fal. The spot is about $13.87 there, and each of the ten 5-second clips is about $2.31. And on a Runway web plan, 2,400 credits at the Academy rate is more than Pro gives you in a month (2,250 credits).

So the split puts cheap seconds where a clip is short and the long take where a cut would show. It costs $5.40 more than going all Gen-4.5, and it saves you the two joins on the one asset that has to hold attention for 30 seconds.

Where to run each engine

Since you can get Seedance 2.5 in several places, the last choice is which door you buy it through. Our Higgsfield vs Seedance comparison asks the same question of Higgsfield and fal.

Runway, when you want both on one balance

Runway is the simplest place to run the split. You get Gen-4.5 for short shots and Seedance 2.5 for the long take from one credit pool, plus Gen-4.5's ProRes and HDR output when the ad goes to an editor. If the subscription is what's holding you back, our Runway alternatives roundup compares six other tools for ad work.

An API host, when you only need raw Seedance seconds

If you're a developer building a pipeline, per-second list prices matter most. Runway's API rate for Seedance 2.5 at 720p is lower than fal's, but fal publishes a token formula that makes odd aspect ratios easy to price in advance. With either one, you don't have to size a plan at all.

Another engine on the shelf, when Seedance is not the fit

If the ad is a short spoken scene, Kling 3.0 is on the same Runway shelf and worth a test render. Our Kling vs Seedance comparison compares the two on audio, length and control.

How Novoads solves the long take without an API account

Novoads is a global AI UGC video-ad generator. You upload a product photo, write a script or have one generated, pick an AI actor and export a vertical ad. We run Seedance 2.5 alongside Seedance 2.0, Seedance 2.0 Mini, Kling v3 Pro, Google Veo 3.1 and Omni Flash, so you can use the Seedance half of this comparison without an API key or a Runway plan.

Seedance 2.5 priced in credits

In Novoads, Seedance 2.5 renders clips of 4 to 30 seconds at 480p, 720p or 1080p. It works in 9:16, 16:9, 1:1 and three other ratios, with sound on by default. These are the prices at 720p.

• 5 seconds: 35 credits.
• 15 seconds: 105 credits.
• 30 seconds: 210 credits.

At 480p it's 3 credits a second. At 1080p it's 12, which comes to 60 credits for 5 seconds and 360 for 30. Plans start at $15/month (Starter, 200 credits per month), and they're all published on /pricing.

Run the worked example's spot and ten 5-second hooks on Seedance 2.5 at 720p, and it comes to 210 + 10 × 35 = 560 credits. That fits inside the 1,000 monthly credits on our $49 Plus plan. At the Plus rate of $0.049 a credit, it's about $27.44, which is more than the $24.00 the same brief costs at Runway's API list price. At 1080p the order flips, because our 12 credits a second come to about $0.59 at the Plus rate, against $0.68 on Runway's API.

There's a cheaper route, too. Test the hooks on Seedance 2.0 Mini, which costs 5 credits for 5 seconds at 720p, and save 2.5 for the long take. That's 210 + 10 × 5 = 260 credits for the whole brief, which is more than Starter's 200 a month. Around the clip, the same credits buy the rest of the ad in one project, meaning the script, the AI actor, a voice in any of 31 languages and the captions.

What Novoads does not do

We don't offer Runway's Gen-4.5, so for the cheap short shot and for ProRes or HDR delivery, you'll want Runway. We run Seedance 2.5 at 480p, 720p and 1080p, as Runway does, but we cap references lower. Novoads takes up to 9 images, 3 videos and 3 audio clips, while Runway's API takes 30, 10 and 10. If your brief needs a large reference board, Runway is the better door. If you need a steady run of product-first vertical ads with a script and an actor, you can start on Novoads.

Price the take, not the second

On Runway's current price list, a second of Gen-4.5 is cheaper than a second of Seedance 2.5, and nothing in this comparison changes that. But what you end up running is a finished take, so that's the thing to price. Put the short visual shots on Gen-4.5, give the take that can't survive a cut to Seedance 2.5, and let the joins you never had to hide make up the difference.