GPT-5.5 Pro vs o3
At a Glance
| Compare |  GPT-5.5 ProOpenAI | o3OpenAI |
|---|---|---|
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $30.00Openai ↗ · Sep 3, 2026 | $1.00Openrouter ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $180.00Openai ↗ · Sep 3, 2026 | $4.00Openrouter ↗ · Sep 3, 2026 |
| Context windowMaximum documented tokens | 1,050K | 200K |
| Model facts checked | Sep 3, 2026View model evidence → | Sep 3, 2026View model evidence → |
Token prices are the lowest available sourced USD rates; input and output may use different providers. Cost ranking estimates output spend on LiveBench, not a full request bill. Ranking methodology →
Available Benchmarks
Side-by-Side Facts
| Field | GPT-5.5 Pro | o3 |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Family | Gpt 5 5 | O3 |
| Model | GPT-5.5 Pro | o3 |
| Version | GPT-5.5 Pro | o3 |
| Lifecycle | active | active |
| Released | 2026-04-23 | 2025-04-16 |
| Knowledge cutoff | 2025-12-01 | 2024-06-01 |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
| Context window | 1,050K | 200K |
| Total parameters | Unknown | Unknown |
| Active parameters | Unknown | Unknown |
| License | Unknown | Unknown |
| Open weights | No | No |
| API available | Yes | Yes |
| Self-hostable | No | No |
| Provider access | Openai (Standard), Openrouter (Standard) | Openai (Standard), Openrouter (Standard) |
| Capabilities | chat, generation, reasoning, structured_outputs, tools | chat, generation, reasoning, structured_outputs, tools |
GPT-5.5 Pro Capabilities
o3 Capabilities
Related Comparisons
All image comparisons →| A | Pair | B | Context |
|---|---|---|---|
GPT-5.5 ProOpenAI | vs | GPT-6 AstraOpenAI | family variantsimage, text |
Claude Fable 5.1Anthropic | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
 Gemini 3.1 ProGoogle DeepMind | vs | GPT-5.5 ProOpenAI | cross-developer peerstext |
 DeepSeek-V4.1-FlashDeepSeek | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
GPT-5.5 ProOpenAI | vs | Grok 4.6xAI | cross-developer peersimage, text |
GPT-5.5 ProOpenAI | vs |  Qwen3.8-MaxQwen | cross-developer peersimage, text |
 Kimi-K3Moonshot AI | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
 MiniMax-M3MiniMax | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
GPT-5.5 ProOpenAI | vs |  GLM-5.3Z.ai | cross-developer peerstext |
GPT-5.5 ProOpenAI | vs |  Hy4 previewTencent | cross-developer peerstext |
Seed 2.1 ProByteDance Seed | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
 Mistral Large 3Mistral AI | vs | GPT-5.5 ProOpenAI | cross-developer peersimage, text |
Primary Evidence
Sources and Freshness
Questions
GPT-5.5 Pro vs o3 FAQs
Is GPT-5.5 Pro or o3 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both GPT-5.5 Pro and o3, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, GPT-5.5 Pro or o3?+
GPT-5.5 Pro is $30.00 and o3 is $1.00 per million tokens, so o3 is cheaper on this metric. GPT-5.5 Pro is $180.00 and o3 is $4.00 per million tokens, so o3 is cheaper on this metric.
Which has a larger context window, GPT-5.5 Pro or o3?+
GPT-5.5 Pro has the larger sourced context window. GPT-5.5 Pro supports 1,050K and o3 supports 200K.
Which performs better in benchmarks, GPT-5.5 Pro or o3?+
There is no overall benchmark winner: At least two independently verified, protocol-matched benchmarks are required for an overall winner.
Can GPT-5.5 Pro or o3 be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. GPT-5.5 Pro is not marked open weight; o3 is not marked open weight.
Can GPT-5.5 Pro and o3 understand images?+
GPT-5.5 Pro is documented with image input; o3 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, GPT-5.5 Pro or o3?+
GPT-5.5 Pro has the larger sourced maximum output: GPT-5.5 Pro supports 128K and o3 supports 100K output tokens.
Do GPT-5.5 Pro and o3 support reasoning and tool use?+
GPT-5.5 Pro: reasoning, tool calling, and image input. o3: reasoning, tool calling, and image input. Feature support does not establish relative quality.
Which is available from more inference providers, GPT-5.5 Pro or o3?+
GPT-5.5 Pro has 2 sourced provider routes; o3 has 2, a tie.
Which offers better value, GPT-5.5 Pro or o3?+
There is no universal value winner. Compare the input and output prices above with the matched benchmark result for your workload: cheaper tokens can be offset by different quality, token usage, latency, or provider availability.