Ranked by GPQA Diamond - 4 open-weight models

Best open-weight AI models for reasoning

In board data through October 15, 2026, DeepSeek V4 Pro ranks first among open-weight models on GPQA Diamond (vendor-reported) with 92.4 (row 11 on the full board), 1.2 points ahead of GLM-5.2 at 91.2. Its list price is $1.32 input / $3.96 output per 1M tokens. A fixed rule, the lowest output price per 1M tokens among models with a registry price that score within 5 points of the top score, picks DeepSeek V4.1 Flash at 90.9 ($0.30 input / $1.20 output per 1M tokens).

Board data through October 15, 2026, checked October 17, 2026. How this is ranked

GPQA Diamond ranking

Best open-weight AI models for reasoning in GPQA Diamond order, with each score's setting and source, scores on related boards, API price per 1M tokens, context window and weights.
Rank	Model	Provider	GPQA Diamond	Source	Input / 1M	Output / 1M	Context	Weights	Humanity's Last Examthru Oct 17, 2026	ARC-AGI-2thru Oct 13, 2026
1	DeepSeek V4 ProBoard: DeepSeek-V4-Pro	DeepSeek	92.4Vendor-reported - GPQA Diamond (Pass@1), 'Comparison with frontier models (Max reasoning effort)' table in DeepSeek-V4.1-Flash model card (original V4-Pro card lists DS-V4-Pro Max at 90.1)	huggingface.co	$1.32	$3.96	1M	Open	-	-
2	GLM-5.2	Z.ai	91.2Vendor-reported - Z.ai full benchmark table; reasoning tasks use temperature=1.0, top_p=0.95, max generation length 163,840 tokens; open weights	z.ai	$1.40	$4.40	1M	Open	-	-
3	DeepSeek V4.1 FlashBoard: DeepSeek-V4.1-Flash	DeepSeek	90.9Vendor-reported - GPQA Diamond (Pass@1), Max reasoning effort; open weights	huggingface.co	$0.30	$1.20	1M	Open	-	-
4	Qwen3.8-27B	Alibaba Cloud (Qwen)	89.2Vendor-reported - Qwen model card Text Performance table (Scientific reasoning); open weights	huggingface.co	$0.50	$3	1M	Open	-	-

Prices in USD per 1M tokens at the standard rate, from each provider's pricing page. A dash means the board name does not match a model in our registry or the model is not on that board. Each related-board score links to its source.

How this is ranked

Board: GPQA Diamond
What it measures: GPQA is a dataset of 448 multiple-choice questions written by domain experts in biology, physics, and chemistry, and GPQA Diamond is its 198-question subset where both expert validators answered correctly and at most one of three non-experts did.
Data through: October 15, 2026 - newest entry date on the board, checked October 17, 2026. Pages publish only while it is within 120 days of the check.
Rows ranked: 4 open-weight models (4 vendor-reported)

Order is the board's own, never a Developers Digest score. Open weights means the model registry lists the weights as open.

Settings and reporters differ between rows: official-leaderboard scores come from the board's own runs, vendor-reported scores from the model maker's card under its own settings, and agents, effort levels and harnesses vary. A single benchmark is not a verdict on a model.

Board notes (10)

No official GPQA Diamond leaderboard exists (the benchmark authors publish only the paper arXiv:2311.12022 and the github.com/idavidrein/gpqa repo); all entries are vendor-reported from model cards and release posts. Third-party aggregator leaderboards were excluded.
Claude Opus 5.5, Claude Sonnet 5.5, Claude Haiku 5.5, Claude Fable 5.1 (self-reported): Anthropic launch-page benchmark grids omit GPQA Diamond, and the Fable 5 & Mythos 5 system card says Anthropic considers GPQA Diamond saturated and plans to stop reporting it. Fable 5.1, Opus 5 and Fable 5 values come from OpenAI comparison tables instead.
GPT-6.1 Sol, GPT-6 Sol, GPT-6 Luna: their OpenAI launch posts have no GPQA Diamond row.
Gemini 3.8 Flash and Gemini 3.7 Flash: Google's own model card (published 2 September 2026) does not list GPQA Diamond; the 95.3% figure is from OpenAI's GPT-6 Astra table.
GLM-5.3: the zai-org/GLM-5.3 model card benchmark table has no GPQA Diamond row (Meta's Muse Spark Open card lists GLM 5.3 (max) at 91.7, DeepSeek's card lists 88.1; neither is Z.ai's own figure).
MiniMax-M3: the official MiniMaxAI/MiniMax-M3 model card could not be read; only third-party figures were found (Z.ai lists 93.0).
xAI Grok 4.5 / 4.6: no official xAI GPQA Diamond figure found; the latest on x.ai is Grok 4 at 87.5% (pass@1), which is not current.
gpt-oss-120b / gpt-oss-20b: the GPQA Diamond values on the OpenAI gpt-oss post could not be extracted cleanly.
Release dates could not be verified for GPT-6 Astra (post has later update notes dated September 22 and 29, 2026), Claude Mythos Preview, Claude Opus 4.7, Claude Fable 5.1 in OpenAI's table, and Gemma 4 model card; date left blank.
Gemini 3 Pro (2025-11-18) and Gemini 3 Flash (2025-12-17) dates are launch dates as recalled, not re-read from the pages today; Muse Spark Open date (2026-10-15) came from a page summary and should be spot-checked.

Rankings

API capabilities

Reasoning

Providers of the top 3

Curated picks

FAQ

What is the best open-weight AI model for reasoning?

DeepSeek V4 Pro ranks first among open-weight models by GPQA Diamond, board data through October 15, 2026, with 92.4 (vendor-reported). One benchmark is not a verdict: settings differ between rows, so test on your own workload before you switch.

What is the cheapest open-weight AI model for reasoning near the top of GPQA Diamond?

Taking every ranked model within 5 points of the top score that has a price in our registry, DeepSeek V4.1 Flash has the lowest output price: $0.30 input / $1.20 output per 1M tokens, with 90.9 by GPQA Diamond, board data through October 15, 2026.

How is this reasoning ranking built?

Rows follow the GPQA Diamond board's own order, checked on October 17, 2026; its newest entry is dated October 15, 2026, and a use case is only published while that date is within 120 days of the check. Each model appears once. Prices, context windows and weights come from each provider's first-party pricing page in our model registry; a model the registry does not list shows a dash.

Newsletter

One email per week. New model releases, the leaderboard moves that matter and what they mean for what you build.