GPT-5.1 vs GPT-5.5
Benchmark Performance
Available Benchmarks
| Benchmark | GPT-5.1 | GPT-5.5 |
|---|---|---|
| ARC-AGI-1verified-v1-15fb467fd4fc · 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-v2-9a3db289984e · 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-2026-07-30-011508720696 · arena_rating · leader | 1,400.8495% of row best · rating · gpt-5.1; 95% CI [1391.40144375, 1410.27736947]; votes 8220; rank 37 | 1,480.30100% of row best · rating · gpt-5.5; 95% CI [1473.46488383, 1487.13183487]; votes 17286; rank 9 |
| LMArena Search Arenasearch-2026-08-24-011508720696 · arena_rating · leader | 1,199.4497% of row best · rating · gpt-5.1-search; 95% CI [1194.20592738, 1204.68165473]; votes 59909; rank 14 | 1,242.05100% of row best · rating · gpt-5.5-search; 95% CI [1236.73488085, 1247.37053078]; votes 89873; rank 3 |
| LMArena Text Arenatext-2026-09-01-011508720696 · arena_rating · leader | 1,422.4797% of row best · rating · gpt-5.1; 95% CI [1418.85253526, 1426.08681113]; votes 43002; rank 96 | 1,466.80100% of row best · rating · gpt-5.5; 95% CI [1462.99653821, 1470.60035247]; votes 64686; rank 27 |
| LMArena Vision Arenavision-2026-08-27-011508720696 · arena_rating · leader | 1,235.1995% of row best · rating · gpt-5.1; 95% CI [1227.44529223, 1242.93837299]; votes 10223; rank 60 | 1,294.36100% of row best · rating · gpt-5.5-high; 95% CI [1287.65516407, 1301.05910249]; votes 20121; rank 18 |
| ToneBench2026-08-28-10-task-cd9819ab6e4d · overall_score · leader | 75.9893% of row best · points · GPT-5.1 · 3,970 output tokens / case | 81.53100% of row best · points · GPT-5.5 (none) · 3,805 output tokens / case |
| Overall ResultCounted from the protocol-matched rows above | 0 benchmark wins | 7 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.
Technical Differences
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 | Unknown | Unknown |
| Output modalities | Unknown | Unknown |
| Context window | 400,000 | 1,050,000 |
| 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 |
13 comparable fields · 6 material differences · Interactive comparison only; indexing gate not met
GPT-5.1 Capabilities
GPT-5.5 Capabilities
Internal Comparison Graph
Related Comparisons
| A | Pair | B | Context |
|---|---|---|---|
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GPT-5.1OpenAI | vs | GPT-5.2OpenAI | family variantsimage, text |
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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 and GPT-5.5 supports 1,050,000.
Which performs better in benchmarks, GPT-5.1 or GPT-5.5?+
GPT-5.5 leads the current overall benchmark count. The result uses 7 protocol-matched benchmarks from 3 publishers; it is not a universal quality score.
Can GPT-5.1 or GPT-5.5 be self-hosted?+
Both models have the same recorded 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 not documented with image input; GPT-5.5 is not documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, GPT-5.1 or GPT-5.5?+
Neither has a larger sourced maximum output. GPT-5.1 is 128,000 and GPT-5.5 is 128,000.
Do GPT-5.1 and GPT-5.5 support reasoning and tool use?+
GPT-5.1: reasoning and tool calling. GPT-5.5: reasoning and tool calling. 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.