Claude Sonnet 4.6 vs GPT-5.3-Codex
Claude Sonnet 4.6 (2026) and GPT-5.3-Codex (2026) compare a standalone API model against a coding-specialized model. Claude Sonnet 4.6 ships a 1m-token context window, while GPT-5.3-Codex ships a 400k-token context window. On SWE-bench Verified, GPT-5.3-Codex leads by 5.4 pts. On pricing, GPT-5.3-Codex costs $1.75/1M input tokens versus $3/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: Claude Sonnet 4.6 is standalone API model, while GPT-5.3-Codex is coding-specialized model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | Claude Sonnet 4.6 | GPT-5.3-Codex |
|---|---|---|
| Product type | Standalone API model | Coding-specialized model |
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 400k |
| Cheapest output | $15/1M tokens | $14/1M tokens |
| Provider routes | 6 tracked | 3 tracked |
| Shared benchmarks | 4 rows | SWE-bench Verified leader |
Decision tradeoffs
- Claude Sonnet 4.6 holds a shared-benchmark lead on τ-bench, ahead by 9.7 points.
- Claude Sonnet 4.6 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Sonnet 4.6 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Sonnet 4.6 uniquely exposes Multimodal and Parallel agents in local model data.
- Local decision data tags Claude Sonnet 4.6 for Coding, RAG, and Agents.
- GPT-5.3-Codex holds a shared-benchmark lead on SWE-bench Verified, ahead by 5.4 points.
- GPT-5.3-Codex has the lower cheapest tracked output price at $14/1M tokens.
- Local decision data tags GPT-5.3-Codex for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Sonnet 4.6
$6,150
Cheapest tracked route/tier: OpenRouter
GPT-5.3-Codex
$4,900
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $1,250. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.3-Codex is $1/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Multimodal and Parallel agents before moving production traffic.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Claude Sonnet 4.6 is $1/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Sonnet 4.6 adds Multimodal and Parallel agents in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-17 | 2026-02-05 |
| Context window | 1m | 400k |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-12 | 2025-08 |
Pricing and availability
| Pricing attribute | Claude Sonnet 4.6 | GPT-5.3-Codex |
|---|---|---|
| Input price | $3/1M tokens | $1.75/1M tokens |
| Output price | $15/1M tokens | $14/1M tokens |
| Providers |
Capabilities
| Capability | Claude Sonnet 4.6 | GPT-5.3-Codex |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | Yes | Yes |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Sonnet 4.6 | GPT-5.3-Codex |
|---|---|---|
| SWE-bench Verified | 79.6 | 85.0 |
| Terminal-Bench 2.0 | 59.1 | 77.3 |
| τ-bench | 87.5 | 77.8 |
| SWE-rebench | 60.7 | 58.2 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Sonnet 4.6 at 79.6 and GPT-5.3-Codex at 85, with GPT-5.3-Codex ahead by 5.4 points; Terminal-Bench 2.0 has Claude Sonnet 4.6 at 59.1 and GPT-5.3-Codex at 77.3, with GPT-5.3-Codex ahead by 18.2 points; τ-bench has Claude Sonnet 4.6 at 87.5 and GPT-5.3-Codex at 77.8, with Claude Sonnet 4.6 ahead by 9.7 points. The largest visible gap is 18.2 points on Terminal-Bench 2.0, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on multimodal input: Claude Sonnet 4.6. Both models share vision, reasoning mode, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Sonnet 4.6 lists $3/1M input and $15/1M output tokens on the cheapest tracked provider, while GPT-5.3-Codex lists $1.75/1M input and $14/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GPT-5.3-Codex lower by about $1.17 per million blended tokens. Availability is 6 providers versus 3, so concentration risk also matters.
Choose Claude Sonnet 4.6 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose GPT-5.3-Codex when coding workflow support and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Sonnet 4.6 or GPT-5.3-Codex?
Claude Sonnet 4.6 supports 1m tokens, while GPT-5.3-Codex supports 400k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Sonnet 4.6 or GPT-5.3-Codex?
GPT-5.3-Codex is cheaper on tracked token pricing. Claude Sonnet 4.6 costs $3/1M input and $15/1M output tokens. GPT-5.3-Codex costs $1.75/1M input and $14/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Sonnet 4.6 or GPT-5.3-Codex open source?
Claude Sonnet 4.6 is listed under Proprietary. GPT-5.3-Codex is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Sonnet 4.6 or GPT-5.3-Codex?
Both Claude Sonnet 4.6 and GPT-5.3-Codex expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Sonnet 4.6 or GPT-5.3-Codex?
Claude Sonnet 4.6 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Sonnet 4.6 and GPT-5.3-Codex?
Claude Sonnet 4.6 is available on OpenRouter, Anthropic, AWS Bedrock, GCP Vertex AI, and Microsoft Foundry. GPT-5.3-Codex is available on OpenRouter, OpenAI API, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-10. Data sourced from public model cards and provider documentation.