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GPT-5.5 Pro

Reasoning effort

GPT-5.5 Pro is an OpenAI proprietary reasoning model, released 23 Apr 2026. Its best configuration (xhigh reasoning effort) ranks #39 of 775 on the BenchLeader Index at 65.3 ±8.3, in the upper half. The ± is the point: 193 other configurations score within that range, so they and this one cannot be told apart on quality alone — price and speed are what separate them. It scores highest in reasoning (78) and lowest in maths (71). At $67.50 per million tokens blended it is among the most expensive ranked models. Output speed of 23 tokens per second puts it in the slowest quarter, with a first token in 4.3 s. It has been measured at 3 reasoning-effort settings; this summary describes the best-scoring one, and the tabs above switch between them. Last measured 23 Apr 2026.stale: no new result in six months

Blended price: $67.50/M; $30.00 in · $180.00 out
Output speed: 23 tok/s; OpenRouter traffic, 7-day median; not yet measured by Artificial Analysis
First answer: 4.35 s
Context: 1.1M
Full answer: –
Cost per run: –
Released: 23 Apr 2026

How it scores by categoryDashed line = average model (50). One step of 15 = one standard deviation.

Overall index65
Reasoning78
Maths71

Versions

OpenAI has shipped 4 models under this name. Each is ranked on its own results; a newer version often has fewer results so far, which holds its index nearer the average until more arrive.

Model	Released	Index	Rank
GPT-5.5 Proxhighthis page	23 Apr 2026	65.3	#39
GPT-5.4 Pro	4 Mar 2026	63.5	#62
GPT-5.2 Proxhigh	11 Dec 2025	–	–
GPT-5 Pro	7 Aug 2025	59.8	#123

Reasoning-effort configurations

The same model behaves differently depending on how much it is allowed to think. Each row is one setting, scored only on the benchmarks that were run at that setting. “Not stated” collects results from publishers that did not say which setting they used; for a reasoning model that is usually its thinking mode, but we do not assume it. Pick a setting here or at the top of the page to see its price, speed and category scores.

Effort	Index	Rank	Speed	First answer	Chat reply cost	Categories
high	–	–	23 tok/s	4.35 s	$0.066	Reasoning 70
xhighbest	65.3	#39	23 tok/s	4.35 s	$0.066	Maths 71 · Reasoning 78
not stated	–	–	23 tok/s	4.35 s	$0.066	Reasoning 73

How its index has moved

19 Sept 2026 to 18 Oct 2026

The index is recomputed from scratch every day, so a line moves when a new benchmark result lands, when a publisher revises a score, or when the models it is normalised against change. Early movement usually means the score is still settling.

Benchmark results

See all LLM benchmarks. One column per reasoning effort. Rank is among every configuration of every model on that benchmark. Hover a score for the run it came from.

Reasoning

Benchmark	high	xhigh	not stated	Source
SimpleBench	76.9%#4	–	76.9%#4	SimpleBench
ARC-AGI-1	96.5%#23	95.0%#35	–	ARC Prize
ARC-AGI-2	84.6%#31	84.2%#34	–	ARC Prize
CritPt	–	30.6%#14	–	Artificial Analysis
Chess Puzzlesnot in index	–	62.0%#8	–	Epoch AI Benchmarking Hub
LMCAnot in index	–	53.9%#48	–	Epoch AI Benchmarking Hub
DTBenchnot in index	–	96.0%#30	–	Epoch AI Benchmarking Hub

Maths

Benchmark	xhigh	Source	Trend
FrontierMath Tiers 1–3	87.7%#8	Epoch AI Benchmarking Hub
FrontierMath Tier 4	78.0%#15	Epoch AI Benchmarking Hub

Composite

Benchmark	not stated	Source	Trend
Epoch Capabilities Indexnot in index	162.9#10	Epoch AI Benchmarking Hub

Where to run it

Every provider serving this model through OpenRouter, with throughput and first-token latency measured on live traffic over the last 30 minutes and each provider’s own price. Purple marks the best in each column.

Provider	Speed	First token	Input $/M	Output $/M	Context	Quantisation
OpenAI	23 tok/s	4.57 s	$30.00	$180.00	1.1M	–

What a task costs

Estimates from list price, output speed and time to first answer for the best configuration. “With caching” assumes three-quarters of the input is served from the prompt cache. Reasoning tokens are not modelled.

Workload	Tokens in / out	Cost	With caching	Time
Chat reply	400 / 300	$0.066	–	17.4 s
Summarize a 30-page report	12,000 / 600	$0.468	–	30.4 s
Code edit	6,000 / 1,500	$0.450	–	1.2 min
Agentic coding session	60,000 / 4,000	$2.52	–	3.0 min
Structured extraction	2,000 / 200	$0.096	–	13.0 s