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Model Comparison

Seedance 2.0 Fast vs Gen-4.5Which Is Better in 2026?

ByteDance: Seedance 2.0 Fast logoByteDance•
Runway

Seedance 2.0 Fast vs Gen-4.5: which should you choose in 2026?

Seedance 2.0 Fast (by ByteDance) and Gen-4.5 (by Runway) are compared below. Here is how they stack up on benchmarks, price, and capabilities, and which one to pick in 2026.

There are not enough shared, protocol-compatible benchmark results to declare a performance leader.

Choose Seedance 2.0 Fast if…

  • • your own prompt tests favor its output; shared comparable evidence does not identify a unique advantage

Choose Gen-4.5 if…

  • • your own prompt tests favor its output; shared comparable evidence does not identify a unique advantage

The benchmark count includes only results measured with a matching benchmark version and protocol. Arena scores are shown separately. Missing, preliminary, and incompatible data is not treated as a controlled win. Published point-score comparisons are labeled separately when protocol details are incomplete. For text-output models, the verdict also compares token pricing and context windows.

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Performance benchmarks

Every value links to its source. A dash means that no reviewed result is available for that exact model and protocol.

Seedance 2.0 Fast and Gen-4.5 benchmark results
BenchmarkSeedance 2.0 FastGen-4.5
AutomationBench-AA

A 657-task benchmark of multi-step work across simulated SaaS applications in six business domains. The Artificial Analysis protocol reports a guardrail-aware score and is distinct from both the public Zapier split and the unrelated dynamic AutoBench framework.

Guardrail-aware score

——
BrowseComp

A benchmark of difficult, verifiable information-seeking questions designed to measure an agent's ability to locate hard-to-find facts through web browsing.

Accuracy

——
OSWorld-Verified

A verified computer-use benchmark in which multimodal agents operate desktop applications and are graded from the resulting environment state.

Mean task reward

——
SWE-Bench Verified

A human-validated subset of real GitHub issues used to measure whether a coding agent can produce repository patches that resolve the associated tests.

Resolved

——
Terminal-Bench 2.1

Version 2.1 of the benchmark for completing realistic tasks in terminal environments. Harness, resource limits, and attempt count are part of the protocol.

Mean task success

——
AutoBench

A dynamic LLM evaluation framework in which models generate questions, answer them, and participate in reciprocal peer assessment. AutoBench is distinct from Zapier's AutomationBench.

Weighted peer-assessment score

——
GPQA Diamond

The highest-quality subset of Graduate-Level Google-Proof Q&A, designed to test expert-level scientific reasoning in biology, physics, and chemistry.

Accuracy

——
Humanity's Last Exam

A 2,500-question expert-level benchmark spanning dozens of academic fields. Tool-assisted and no-tools results are separate protocols and must not be merged.

Accuracy

——

Benchmark sources

    Reviewed evidence last updated 2026-08-09.

    Pricing, capabilities, and model facts

    Seedance 2.0 Fast and Gen-4.5 model facts
    FeatureSeedance 2.0 FastGen-4.5
    Context & model facts
    DeveloperByteDanceRunway
    API providerByteDanceRunway
    Input context——
    Maximum output——
    Released——
    Added to WritingmateApr 15, 2026Jul 29, 2026
    LicenseNot availableNot available
    Knowledge cutoff——
    Capabilities
    InputsText, Image, Video, AudioText, Image
    OutputsVideoVideo
    Provider endpoint accepts tool parametersNoNo
    ReasoningNoNo
    VisionYesYes
    Image GenerationNoNo
    Video GenerationYesYes
    API performance
    p95 latencyNot measuredNot measured
    Output throughputNot measuredNot measured
    Writingmate shows API performance only when both models have enough observations from the same measurement window, prompt profile, and provider. Third-party latency values are not copied into this table.

    Data sources

    • Writingmate model catalog (pricing, limits, and availability)

    Catalog data last updated Jul 29, 2026.

    Why Pay for Multiple Subscriptions?

    Comparing Seedance 2.0 Fast from ByteDance with Gen-4.5 from Runway? Instead of managing separate API keys and subscriptions, get both with Writingmate.

    Subscription-plan access for Seedance 2.0 Fast and Gen-4.5
    PlanPriceSeedance 2.0 FastGen-4.5AI ImagesAI Video
    Writingmate Pro
    Most popular
    		$20/moIncludedIncludedNano Banana Pro, FLUX.2, DALL-E & moreSora 2, VEO 3.1
    Writingmate Ultimate
    Power users
    		$60/moIncludedIncludedNano Banana Pro, FLUX.2, DALL-E & moreSora 2, VEO 3.1
    View Plans & Pricing

    Seedance 2.0 Fast vs Gen-4.5 FAQ

    Which is better, Seedance 2.0 Fast or Gen-4.5?

    There are not enough shared, protocol-compatible benchmark results to declare a performance leader.

    Which model is cheaper to use through an API?

    A comparable blended token price is not available for both models. Check the API pricing rows for the values that are currently published.

    Which model supports more context?

    Comparable context-window data is not available for both models.

    Can I switch between Seedance 2.0 Fast and Gen-4.5?

    Yes. Use the model selector on this page to open any current Writingmate model comparison. You can also run the same prompt with both models in Writingmate.