GPT-5.5 vs o3
GPT-5.5 and o3 are both OpenAI reasoning models, but they serve different production decisions. GPT-5.5 is the 2026 frontier pick for long-context agentic coding, computer-use workflows, and newer internal knowledge. o3 is the cheaper, faster reasoning route when the task fits inside 200K tokens and does not require post-2024 knowledge.
Pick GPT-5.5 for large-codebase analysis, long-context agents, recent-knowledge research, computer-use automation, and coding accuracy: it has 1.05M context versus 200K, a December 2025 documented knowledge cutoff versus June 2024, GPQA Diamond at 93.6% versus 87.7%, and SWE-Bench Verified at 82.6% versus 71.7%. Pick o3 for cost-sensitive reasoning, math/science Q&A, batch jobs, and latency-sensitive flows under 200K tokens: OpenAI pricing is $2/M input and $8/M output versus GPT-5.5 at $5/M and $30/M, and Artificial Analysis reports materially faster output throughput for o3.
Decision scorecard
Local evidence first| Signal | GPT-5.5 | o3 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1.05m | 200k |
| Cheapest output | $30/1M tokens | $8/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | SWE-bench Verified leader | 8 shared |
Decision tradeoffs
- GPT-5.5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 10.9 points.
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags GPT-5.5 for Coding, RAG, and Agents.
- o3 holds a shared-benchmark lead on AIME 2025, ahead by 7.7 points.
- o3 has the lower cheapest tracked output price at $8/1M tokens.
- Local decision data tags o3 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.
GPT-5.5
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
o3
$3,600
Cheapest tracked route/tier: OpenAI API
Estimated monthly gap: $7,900. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenAI API, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
- o3 is $22/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Provider overlap exists on OpenAI API, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.5 is $22/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-23 | 2025-04-16 |
| Context window | 1.05m | 200k |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-12 | 2024-06 |
Pricing and availability
| Pricing attribute | GPT-5.5 | o3 |
|---|---|---|
| Input price |
| $2/1M tokens |
| Output price |
| $8/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.5 | o3 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | GPT-5.5 | o3 |
|---|---|---|
| SWE-bench Verified | 82.6 | 71.7 |
| Google-Proof Q&A | 93.6 | 87.7 |
| AIME 2025 | 81.2 | 88.9 |
| Humanity's Last Exam | 41.4 | 20.3 |
| HumanEval | 94.2 | 96.7 |
| Chatbot Arena | 1488.0 | 1412.0 |
| MMMU Pro | 88.3 | 76.4 |
| Aider Polyglot | 88.0 | 81.3 |
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.