GPT-5.1 vs GPT-5.5
At a Glance
| Compare |  GPT-5.1OpenAI | GPT-5.5OpenAI |
|---|---|---|
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $1.25Openai ↗ · Sep 3, 2026 | $5.00Openai ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $10.00Openai ↗ · Sep 3, 2026 | $30.00Openai ↗ · Sep 3, 2026 |
| Context windowMaximum documented tokens | 400K | 1,050K |
| 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
| Benchmark | GPT-5.1 | GPT-5.5 |
|---|---|---|
| ARC-AGI-1verified-v1-613c385b0c93 · verified_score · leader | 72.8377% of row best · percent · GPT-5.1 (Thinking, High) | 95.00100% of row best · percent · GPT-5.5 (XHigh) |
| ARC-AGI-2verified-v2-be40992860f9 · verified_score · leader | 17.6421% of row best · percent · GPT-5.1 (Thinking, High) | 85.00100% of row best · percent · GPT-5.5 (XHigh) |
| LMArena Document Arenadocument-2026-09-13-a64ca3b12b6e · arena_rating · leader | 1,403.1795% of row best · rating · gpt-5.1; 95% CI [1393.82886201, 1412.50542979]; votes 8244; rank 42 | 1,484.48100% of row best · rating · gpt-5.5-high; 95% CI [1478.10008380, 1490.85597001]; votes 20944; rank 9 |
| LMArena Search Arenasearch-2026-10-13-a64ca3b12b6e · arena_rating · leader | 1,199.7096% of row best · rating · gpt-5.1-search; 95% CI [1194.51255947, 1204.89089087]; votes 63042; rank 20 | 1,246.55100% of row best · rating · gpt-5.5-search; 95% CI [1241.65410036, 1251.45490149]; votes 125957; rank 4 |
| LMArena Text Arenatext-2026-10-15-a64ca3b12b6e · arena_rating · leader | 1,422.2897% of row best · rating · gpt-5.1; 95% CI [1418.72432020, 1425.83291138]; votes 44434; rank 110 | 1,466.80100% of row best · rating · gpt-5.5; 95% CI [1463.14500791, 1470.45729846]; votes 70985; rank 35 |
| LMArena Vision Arenavision-2026-10-09-a64ca3b12b6e · arena_rating · leader | 1,234.8196% of row best · rating · gpt-5.1; 95% CI [1227.28917044, 1242.33289013]; votes 10818; rank 76 | 1,292.31100% of row best · rating · gpt-5.5-high; 95% CI [1286.39749993, 1298.21557690]; votes 26281; rank 26 |
| Overall ResultCounted from the protocol-matched rows above | 0 benchmark wins | 6 benchmark winsOverall lead |
Third-party benchmark Only like-for-like primary-publisher results are shown; raw scores, relative scores, configuration, and token spend remain visible.
Side-by-Side Facts
| Field | GPT-5.1 | GPT-5.5 |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Family | Gpt 5 1 | Gpt 5 5 |
| Model | GPT-5.1 | GPT-5.5 |
| Version | GPT-5.1 | GPT-5.5 |
| Lifecycle | active | active |
| Released | 2025-11-13 | 2026-04-23 |
| Knowledge cutoff | 2024-09-30 | 2025-12-01 |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
| Context window | 400K | 1,050K |
| 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-5.1 Capabilities
GPT-5.5 Capabilities
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Primary Evidence
Sources and Freshness
Questions
GPT-5.1 vs GPT-5.5 FAQs
Is GPT-5.1 or GPT-5.5 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both GPT-5.1 and GPT-5.5, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, GPT-5.1 or GPT-5.5?+
GPT-5.1 is $1.25 and GPT-5.5 is $5.00 per million tokens, so GPT-5.1 is cheaper on this metric. GPT-5.1 is $10.00 and GPT-5.5 is $30.00 per million tokens, so GPT-5.1 is cheaper on this metric.
Which has a larger context window, GPT-5.1 or GPT-5.5?+
GPT-5.5 has the larger sourced context window. GPT-5.1 supports 400,000 tokens and GPT-5.5 supports 1,050,000 tokens.
Which performs better in benchmarks, GPT-5.1 or GPT-5.5?+
GPT-5.5 leads the current overall benchmark count. The result uses 6 protocol-matched benchmarks from 2 publishers; it is not a universal quality score.
Can GPT-5.1 or GPT-5.5 be self-hosted?+
Both models have the same sourced self-hosting status: unsupported. GPT-5.1 is not marked open weight; GPT-5.5 is not marked open weight.
Can GPT-5.1 and GPT-5.5 understand images?+
GPT-5.1 is documented with image input; GPT-5.5 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, GPT-5.1 or GPT-5.5?+
Both models have the same sourced maximum output: 128,000 tokens each.
Do GPT-5.1 and GPT-5.5 support reasoning and tool use?+
GPT-5.1: reasoning, tool calling, and image input. GPT-5.5: reasoning, tool calling, and image input. Feature support does not establish relative quality.
Which is available from more inference providers, GPT-5.1 or GPT-5.5?+
GPT-5.1 has 2 sourced provider routes; GPT-5.5 has 2, a tie.
Which offers better value, GPT-5.1 or GPT-5.5?+
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.