Claude Sonnet 4 vs GPT-5.5
A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.
Updated
Claude Sonnet 4 specs · GPT-5.5 specs- PriceClaude Sonnet 4
Claude Sonnet 4 publishes pricing ($15.00 / 1M output tokens) while GPT-5.5 does not.
- Context windowGPT-5.5
GPT-5.5 accepts 400K tokens vs 200K, 2.0× 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 Claude Sonnet 4.
- OpennessTie
Both are closed-weight, API-only.
On balance GPT-5.5 edges ahead, winning 2 of 5 categories against Claude Sonnet 4's 1. Claude Sonnet 4 publishes pricing ($15.00 / 1M output tokens) while GPT-5.5 does not. GPT-5.5 accepts 400K tokens vs 200K, 2.0× 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, Claude Sonnet 4 handles text, vision while GPT-5.5 handles text, vision, audio, which can be the deciding factor before you even look at benchmarks. Both are closed-weight, API-only.
GPT-5.5 is the newer of the two, released 9 months after Claude Sonnet 4, which usually means a more recent knowledge cutoff and updated safety post-training. Claude Sonnet 4 is usually picked for coding llm and rag workloads, while GPT-5.5 sees more deployments in agents and tool use. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.
Side-by-side specs
| Spec | Claude Sonnet 4 | GPT-5.5 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | May 2025 | Mar 2026 |
| Modalities | text, vision | text, vision, audio |
| Context window | 200K tokens | 400K tokens |
| Max output | , | , |
| Input · 1M | $3.00 / 1M tokens | Pricing not published |
| Output · 1M | $15.00 / 1M tokens | Pricing not published |
| Knowledge cutoff | 2025-03 | , |
| Open weights | No | No |
| API available | Yes | Yes |
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$31.50 vs ,
- Heavy usage, 1M in / 500k out per day$315 vs ,
- RAG workload, 5M in / 200k out per day$540 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).
Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.
- Claude Sonnet 4$1.05
- GPT-5.5Pricing unavailable
Benchmarks compared
Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.
- SWE-bench Verified65.0
Claude Sonnet 4 fits when…
- Solid all-rounder
- Mature deployment ecosystem
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 200K for Claude Sonnet 4.
- Multimodal needs covering audio.
Consider Claude Opus 4.7
Anthropic's mid-2026 flagship, ahead on SWE-bench, agent reliability, and writing quality.
Frequently asked
Is Claude Sonnet 4 or GPT-5.5 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 200K for Claude Sonnet 4.Is Claude Sonnet 4 or GPT-5.5 better for coding?
Both Claude Sonnet 4 and GPT-5.5 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?
Neither model ships open weights, both are accessible only via their respective providers' APIs.When were Claude Sonnet 4 and GPT-5.5 released?
Claude Sonnet 4 was released by Anthropic on 2025-05-22. GPT-5.5 was released by OpenAI on 2026-03-01.
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