Head-to-head
GPT-5.5 vs Grok 4.3: which AI model wins in 2026?
GPT-5.5 ($30/1M out) and Grok 4.3 ($2.50/1M out) are two of the most-used AI models in 2026. Across 3 community votes, GPT-5.5 leads with 57% approval.
Quick verdict
On Reasoning, pick GPT-5.5: the arena rates it 5/5 against 4/5 for Grok 4.3. On budget, Grok 4.3 wins: it starts at $2.50/1M out versus $30/1M out for GPT-5.5.
Line-by-line comparison
Strengths and weaknesses
GPT-5.5
- 1M-token context window (1,050,000) with 128K max output and reasoning effort tunable from none to xhigh
- State-of-the-art ARC-AGI-2 at 85.0% (vs 73.3% for GPT-5.4) and Terminal-Bench 2.0 at 82.7%
- Strong agentic coding autonomy: devs report it one-shots tasks that took GPT-5.4 multiple turns and fixes its own mistakes; +50 points on Code Arena vs GPT-5.4
- Aggressive discounts: 90% off cached input ($0.50/1M) and 50% off via Batch or Flex ($2.50/$15)
- Fast for a frontier reasoner: devs say it is the first GPT model comfortable to run at medium or low thinking effort
- List price doubled vs GPT-5.4 ($5/$30 vs $2.50/$15) for the same 1M-token context window
- Overly literal instruction-following: devs report it fails to infer intent in obvious places where Claude succeeds
- Trails Claude Opus 4.8 on SWE-bench Pro (58.6% vs 69.2%); HN developers still favor Claude roughly 2:1 for coding
- Sometimes too conservative with code changes or skips deep reasoning entirely, answering immediately on complex prompts
- Long-context surcharge: prompts over 272K input tokens are billed 2x input and 1.5x output for the whole session
Grok 4.3
- Aggressive pricing: $1.25/$2.50 per 1M tokens, 58% cheaper input and 83% cheaper output than Grok 4, undercutting GPT-5.5 and Gemini 3.1 Pro
- Major agentic leap: +321 Elo on GDPval-AA versus Grok 4.20, with strong tool calling and instruction following
- Cached input at $0.20/1M (84% discount), a big saver for repeated agent loops
- Configurable reasoning effort (none/low/medium/high) in one model at one price, no routing between fast and deep variants
- Praised on HN for natural, concise tone and token-dense outputs that lower real-world costs
- Solid throughput around 130 output tokens/sec (Artificial Analysis)
- Coding reasoning judged 'not competitive with the big April releases' by HN developers; intelligence frontier barely moved since Grok 4
- Non-hallucination score dropped 8 points vs Grok 4.20 on AA-Omniscience; 4.20 remains xAI's safer pick for precision-critical domains
- High time to first token (~13s at high reasoning effort per Artificial Analysis), painful for interactive apps
- Context window shrank to 1M from Grok 4.20's 2M
- Recurring trust and safety complaints (harmful content reports, inconsistent behavior) and no MCP/connected-apps support in the consumer app
Cast your verdict
One recommendation per tool per gladiator. It reshapes the crowd score everyone sees.
The arena’s verdict on GPT-5.5
Pick GPT-5.5 over GPT-5.4 if you need stronger agentic autonomy, terminal-heavy workflows, or SOTA abstract reasoning, but know the list price doubled from GPT-5.4's $2.50/$15 to $5/$30 while the 1M-token context stayed the same. Teams doing high-stakes multi-file refactoring may still prefer Claude Opus, which leads SWE-bench Pro (69.2% vs 58.6%) and infers intent better from loose prompts. Budget-sensitive users should mind the 272K-token surcharge and reports of faster limit burn, and lean on caching, Batch, or Flex to halve costs.
The arena’s verdict on Grok 4.3
Pick Grok 4.3 if you run agentic or high-volume pipelines where cost per call dominates: it delivers near-frontier reasoning and a big tool-calling jump over Grok 4.20 at a fraction of GPT-5.5 or Gemini 3.1 Pro pricing. Skip it if coding precision is your priority, as developers still rank Claude and the big April releases ahead. Also stay on Grok 4.20 if you need its 2M context or its better non-hallucination score for legal, medical, or compliance work. Latency-sensitive apps should test the ~13s time to first token before committing.
What the crowd says
On GPT-5.5
“It is painfully literal. Where Claude infers intent in obvious places, 5.5 wants everything spelled out. And the price doubled vs 5.4 for the same 1M context.”
“85 on ARC-AGI-2 and you can feel it. Stuff that used to stall my agent just resolves now. 1M context with 128K output covers every workflow I have.”
“5.5 one-shots tasks that took 5.4 three turns, and it fixes its own mistakes mid-run instead of doubling down. The reasoning effort dial from none to xhigh is genuinely useful.”
On Grok 4.3
No verdicts yet. Be the first to speak.
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Frequently asked questions
Is GPT-5.5 better than Grok 4.3?
The crowd currently sides with GPT-5.5: 57% recommend it, versus 50% for Grok 4.3 (3 votes). On Reasoning, GPT-5.5 rates higher (5/5 vs 4/5). The right pick depends on your use case. The line-by-line comparison on this page breaks down pricing, key specs and arena ratings.
Which is cheaper, GPT-5.5 or Grok 4.3?
Grok 4.3 is cheaper: it starts at $2.50/1M out, while GPT-5.5 starts at $30/1M out.
How much do GPT-5.5 and Grok 4.3 cost per 1M tokens?
GPT-5.5: $5/1M in per 1M input tokens, $30/1M out per 1M output tokens. Grok 4.3: $1.25/1M in per 1M input tokens, $2.50/1M out per 1M output tokens.