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GPT-5.5 vs Llama 4 405B

A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.

Updated

GPT-5.5 specs · Llama 4 405B specs
Verdict by category
  • PriceTie

    Neither model publishes per-token API pricing.

  • Context windowGPT-5.5

    GPT-5.5 accepts 400K tokens vs 256K, 1.6× the room for long documents and codebases.

  • BenchmarksTie

    No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores.

  • ModalitiesGPT-5.5

    GPT-5.5 supports 3 modalities (text, vision, audio) vs 2 for Llama 4 405B.

  • OpennessLlama 4 405B

    Llama 4 405B ships open weights (Llama 4 Community License); GPT-5.5 is API-only.

On balance GPT-5.5 edges ahead, winning 2 of 5 categories against Llama 4 405B's 1. Neither model publishes per-token API pricing. GPT-5.5 accepts 400K tokens vs 256K, 1.6× the room for long documents and codebases.

No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores. They differ in modality coverage, GPT-5.5 handles text, vision, audio while Llama 4 405B handles text, vision, which can be the deciding factor before you even look at benchmarks. Llama 4 405B ships open weights (Llama 4 Community License); GPT-5.5 is API-only.

GPT-5.5 is the newer of the two, released 11 months after Llama 4 405B, which usually means a more recent knowledge cutoff and updated safety post-training. GPT-5.5 is usually picked for agents and tool use workloads, while Llama 4 405B sees more deployments in open source llm and fine tuning. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.

Side-by-side specs

SpecGPT-5.5Llama 4 405B
ProviderOpenAIMeta
ReleasedMar 2026Apr 2025
Modalitiestext, vision, audiotext, vision
Context window400K tokens256K tokens
Max output,,
Input · 1MPricing not publishedPricing not published
Output · 1MPricing not publishedPricing not published
Knowledge cutoff,2024-12
Open weightsNoYes (Llama 4 Community License)
API availableYesYes

Pricing at scale

What you'd actually pay at typical workloads. Numbers come from each model's published per-million-token rates.

  • Light usage, 100k in / 50k out per day, vs ,
  • Heavy usage, 1M in / 500k out per day, vs ,
  • RAG workload, 5M in / 200k out per day, vs ,

Light usage, 100k in / 50k out per day: pricing not directly comparable (one or both models are missing public per-token rates). Heavy usage, 1M in / 500k out per day: pricing not directly comparable (one or both models are missing public per-token rates). RAG workload, 5M in / 200k out per day: pricing not directly comparable (one or both models are missing public per-token rates).

Price calculator

Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.

  • GPT-5.5Pricing unavailable
  • Llama 4 405BPricing unavailable

Benchmarks compared

Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.

Benchmark scores not yet available. We only publish numbers we can source from official model cards or independent leaderboards, see methodology.
Pick GPT-5.5 if

GPT-5.5 fits when…

  • Industry-leading tool-use and function-calling reliability
  • Strong end-to-end agent performance across SWE-bench and GAIA
  • Wide ecosystem support, ChatGPT, Realtime API, Responses API
  • Long-context tasks, handles 400K tokens vs 256K for Llama 4 405B.
  • Multimodal needs covering audio.
Pick Llama 4 405B if

Llama 4 405B fits when…

  • Strongest open-weight model at launch
  • Multimodal (text + vision)
  • Wide hosting availability
  • Self-hosting and on-prem requirements, open weights (Llama 4 Community License).
Don't want either?

Consider GPT-5

OpenAI's unified flagship combining GPT-line breadth with built-in reasoning, replacing both GPT-4o and the o-series for most users.

See GPT-5 specsGPT-5.5 vs GPT-5Llama 4 405B vs GPT-5

Frequently asked

  • Is GPT-5.5 or Llama 4 405B cheaper?
    Per-token pricing isn't published for at least one of these models, check each model's spec page for current rates.
  • Which has the larger context window?
    GPT-5.5 accepts 400K tokens vs 256K for Llama 4 405B.
  • Is GPT-5.5 or Llama 4 405B better for coding?
    Both GPT-5.5 and Llama 4 405B are competitive on coding benchmarks. See each model's individual spec page for HumanEval and SWE-bench scores where published. For an opinionated pick, consult our Best LLM for Coding ranking.
  • Are either of these models open source?
    Llama 4 405B ships open weights (Llama 4 Community License). GPT-5.5 is API-only.
  • When were GPT-5.5 and Llama 4 405B released?
    GPT-5.5 was released by OpenAI on 2026-03-01. Llama 4 405B was released by Meta on 2025-04-05.
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