GPT-5.6 Sol vs Grok 4.5

Name: GPT-5.6 Sol
Author: OpenAI

GPT-5.6 Sol and Grok 4.5 are the July 2026 flagship routes from OpenAI and xAI for coding agents, tool-heavy workflows, and long-context API work. GPT-5.6 Sol is the primary GPT-5.6 compare anchor with a 1.05M-token context window and OpenAI GA launch rows. Grok 4.5 is available through Grok Build, Cursor, and the SpaceXAI API/console, with tiered pricing at a 200K prompt threshold and an EU launch-day availability caveat from xAI.

Pick GPT-5.6 Sol when you want OpenAI's July 2026 frontier stack, the larger 1.05M context window, and OpenAI-sourced GA rows such as DeepSWE 1.1 at 72.7% and GPQA Diamond at 94.6%. Pick Grok 4.5 when xAI's lower standard-tier API pricing ($2/$6 per 1M tokens for prompts up to 200K) and Grok Build/Cursor distribution matter more, and run your own acceptance tests because several Grok 4.5 chart scores are xAI first-party only. Do not treat Terra or Luna as the OpenAI flagship in this pair.

Decision scorecard

Local evidence first

Signal	GPT-5.6 Sol	Grok 4.5	How to read it
Product type	Standalone API model	Coding-specialized model	Read downstream rows through the product-type lens before comparing benchmarks, prices, or provider availability.
Best for	reasoning-heavy apps, multimodal apps, and tool-calling agents	custom coding agents, code generation, and tool loops	Use-case synthesis from product type, capability flags, context, and provider data.
Decision fit	Coding, RAG, and Agents	Coding, RAG, and Agents	Primary workload tags from local decision data.
Context window	1.05m	500k	Higher is better when prompts, retrieval chunks, or transcripts are large.
Cheapest output	$30/1M tokens	$6/1M tokens	Cheapest tracked provider route; verify your exact region and tier.
Provider routes	2 tracked	3 tracked	Broader coverage can reduce vendor lock-in and fallback risk.
Shared benchmarks	8 shared	SWE-bench Pro leader	Visible benchmark lead is 0.1 points on SWE-bench Pro.

Decision tradeoffs

Choose GPT-5.6 Sol when...

GPT-5.6 Sol holds a shared-benchmark lead on Terminal-Bench 2.1, ahead by 5.5 points.
GPT-5.6 Sol has the larger context window for long prompts, retrieval packs, or transcript analysis.
Local decision data tags GPT-5.6 Sol for Coding, RAG, and Agents.

Choose Grok 4.5 when...

Grok 4.5 holds a shared-benchmark lead on SWE-bench Pro, ahead by 0.1 points.
Grok 4.5 has the lower cheapest tracked output price at $6/1M tokens.
Grok 4.5 has broader tracked provider coverage for fallback and route flexibility.
Local decision data tags Grok 4.5 for Coding, RAG, and Agents.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate Grok 4.5

Requests / monthInput tokens / requestOutput tokens / request

GPT-5.6 Sol

$11,500

Cheapest tracked route/tier: OpenAI API 0-272K input tokens

Grok 4.5

$3,100

Cheapest tracked route/tier: xAI Console <=200K prompt tokens

Estimated monthly gap: $8,400. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

GPT-5.6 Sol -> Grok 4.5

Provider overlap exists on OpenRouter; start route-level A/B tests there.
Grok 4.5 is $24/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.

Grok 4.5 -> GPT-5.6 Sol

Provider overlap exists on OpenRouter; start route-level A/B tests there.
GPT-5.6 Sol is $24/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.

Specs

Specification	GPT-5.6 Sol OpenAI	Grok 4.5 xAI
Released	2026-07-09	2026-07-08
Context window	1.05m	500k
Parameters	—	—
Architecture	Decoder Only	-
License	Proprietary	Proprietary
Openness	Proprietary	Proprietary
Weights	Not released	Not released
Code	Unknown	Unknown
Commercial use	Commercial use: conditional	Commercial use: conditional
Knowledge cutoff	-	-

Pricing and availability

Pricing attribute	GPT-5.6 Sol	Grok 4.5
Input price	0-272K input tokens $5/1M tokens Standard GPT-5.6 Sol token pricing before the long-context surcharge threshold. 272K+ input tokens $10/1M tokens Long-context surcharge applies above 272K input tokens for the full request.	<=200K prompt tokens $2/1M tokens Standard Grok 4.5 tier for prompts up to 200K tokens; cache_read stores this tier's $0.50/M cached-input price. >200K prompt tokens $4/1M tokens Long-context Grok 4.5 tier for prompts above 200K tokens; cache-read price is $1.00/M per xAI model page payload.
Output price	0-272K input tokens $30/1M tokens Standard GPT-5.6 Sol token pricing before the long-context surcharge threshold. 272K+ input tokens $45/1M tokens Long-context surcharge applies above 272K input tokens for the full request.	<=200K prompt tokens $6/1M tokens Standard Grok 4.5 tier for prompts up to 200K tokens; cache_read stores this tier's $0.50/M cached-input price. >200K prompt tokens $12/1M tokens Long-context Grok 4.5 tier for prompts above 200K tokens; cache-read price is $1.00/M per xAI model page payload.
Providers	OpenAI API OpenRouter	xAI Console OpenRouter Vercel AI Gateway

Capabilities

Capability	GPT-5.6 Sol	Grok 4.5
Vision	Yes	Yes
Multimodal	Yes	Yes
Reasoning	Yes	Yes
JSON / Tool use	Yes	Yes
Structured outputs	No	No
Code execution	Yes	Yes
IDE integration	No	No
Computer use	No	No
Parallel agents	No	No

Benchmarks

Benchmark	GPT-5.6 Sol	Grok 4.5
SWE-bench Pro	64.6	64.7
Terminal-Bench 2.1	88.8	83.3
DeepSWE 1.1	72.7	53.0
CursorBench	52.6	63.5
CursorBench	67.2	63.5
CursorBench	60.0	63.5
CursorBench	64.5	63.5
CursorBench	63.5	63.5

Continue comparing

Model pages

Labs and families

Last reviewed: 2026-07-10. Data sourced from public model cards and provider documentation.

Both models

GPT-5.6 Sol Grok 4.5