Grok 4.3 vs ChatGPT 5.5: Budget Frontier vs Premium Frontier in May 2026
xAI shipped Grok 4.3 on April 30 with steep price cuts and native video input. OpenAI shipped GPT-5.5 a week earlier with the highest published Terminal-Bench 2.0 score. Here is how to choose between them.
The frontier model lineup reset twice in late April 2026. OpenAI released GPT-5.5 on April 23. xAI released Grok 4.3 on April 30. Both models target the same workload categories from very different price points. GPT-5.5 ships at $5 per million input tokens and $30 per million output tokens with the highest published Terminal-Bench 2.0 score at 82.7%. Grok 4.3 ships at $1.25 input and $2.50 output, roughly 12x cheaper on output, with native video input and the lowest hallucination rate among its peer group.
This is a clean budget versus premium comparison. Picking between them is mostly a question of whether output quality compounds into enough downstream value to justify the price gap.
The Models at a Glance
| Grok 4.3 | ChatGPT 5.5 | |
|---|---|---|
| Release | April 30, 2026 | April 23, 2026 |
| Context window | 1M tokens | 1M tokens |
| Multimodal input | Text, image, native video | Text, image |
| Variants | Grok 4.3 | GPT-5.5, GPT-5.5 Pro |
| Headline capability | Native video input, low cost | Highest Terminal-Bench 2.0 score |
| Availability | xAI API, OpenRouter | ChatGPT, OpenAI API, Azure |
| Input pricing (per 1M) | $1.25 | $5.00 (Standard), $30.00 (Pro) |
| Output pricing (per 1M) | $2.50 | $30.00 (Standard), $180.00 (Pro) |
| Intelligence Index (Artificial Analysis) | 53 | 60 |
What Each Release Changed
Grok 4.3
The headline change is pricing. Input dropped roughly 40% and output dropped roughly 60% versus Grok 4.20. xAI is positioning Grok 4.3 as a budget conscious alternative to top tier closed models, with capability close enough to the frontier to be defensible for a wide range of production workloads.
Native video input is the first time an xAI API model has processed video frames directly through a vision encoder. For workflows that need to reason over video content, Grok 4.3 is now a viable primitive without an external vision pipeline.
On benchmarks, Grok 4.3 leads CaseLaw v2 at 79.3% and CorpFin among published numbers, and posts a 1500 ELO on GDPval-AA. The Artificial Analysis Intelligence Index score of 53 trails GPT-5.5 (60), Opus 4.7 (57), and Gemini 3.1 Pro Preview (57).
GPT-5.5
GPT-5.5 ships with the highest Artificial Analysis Intelligence Index score in the comparison at 60. Terminal-Bench 2.0 hits 82.7%, the highest published score on that benchmark. SWE-bench Pro at 58.6%. FrontierMath Tier 4 at 35.4%. OSWorld-Verified at 78.7%, which keeps GPT in the lead on computer use that GPT-5.4 established.
OpenAI also claims GPT-5.5 uses 40% fewer tokens than GPT-5.4 to reach the same conclusions, which offsets some of the premium per token pricing on reasoning heavy workloads. GPT-5.5 Pro is available at $30 / $180 per million tokens for the hardest reasoning workloads where maximum cognitive depth is required.
Benchmark Comparison
| Benchmark | Grok 4.3 | GPT-5.5 | Edge |
|---|---|---|---|
| Artificial Analysis Intelligence Index | 53 | 60 | GPT |
| Terminal-Bench 2.0 | not directly reported | 82.7% | GPT |
| SWE-Bench Pro | not directly reported | 58.6% | GPT |
| OSWorld-Verified (computer use) | not directly reported | 78.7% | GPT |
| FrontierMath Tier 4 | not directly reported | 35.4% | GPT |
| GDPval-AA (ELO) | 1500 | not directly reported | Grok (on this metric) |
| CaseLaw v2 | 79.3% (#1) | not directly reported | Grok |
| CorpFin | #1 | not directly reported | Grok |
GPT-5.5 leads on the published agentic coding, computer use, and frontier mathematics benchmarks. Grok 4.3 leads on the published legal and financial domain benchmarks. The two models do not publish on the same benchmark suites, which makes a clean apples to apples comparison difficult, but the headline pattern is clear: GPT-5.5 carries the harder published scores at a substantially higher price point.
Multimodal Capability
Grok 4.3 introduced native video input as an xAI first. The model processes video frames through a vision encoder without an external transcription or sampling pipeline. For any workflow involving video content (training data analysis, content moderation, video QA), this simplifies the architecture meaningfully.
GPT-5.5 supports text and image input. OpenAI has not announced native video input on GPT-5.5. For workflows that need video reasoning, Grok 4.3 is the only model in this comparison that handles it natively as part of a single API call.
For image and computer use workflows, GPT-5.5 retains the lead OpenAI established with GPT-5.4. OSWorld-Verified at 78.7% is the highest published computer use score among production models.
Agentic Capability
GPT-5.5 leads. Terminal-Bench 2.0 at 82.7% is the highest published score on the canonical agentic coding benchmark. SWE-bench Pro at 58.6% is competitive with Opus 4.7's 64.3% and ahead of every other major model. OSWorld-Verified at 78.7% sustains the lead on computer use.
Grok 4.3 has not published direct Terminal-Bench 2.0 or SWE-bench Pro numbers. The GDPval-AA ELO of 1500 is a strong signal on agentic professional work in non coding domains, but it is not a substitute for the published agentic coding scores GPT carries.
For teams whose core workload is engineering agents or computer use automation, GPT-5.5 is the stronger primitive. For teams whose agents operate in legal, finance, or general professional knowledge work domains, Grok 4.3 is competitive at a much lower price point.
Pricing and Total Cost
| Grok 4.3 | GPT-5.5 | GPT-5.5 Pro | |
|---|---|---|---|
| Input per 1M | $1.25 | $5.00 | $30.00 |
| Output per 1M | $2.50 | $30.00 | $180.00 |
| Batch / Flex discount | not directly reported | 50% off (Batch and Flex) | 50% off (Batch and Flex) |
| Priority surcharge | not applicable | 2.5x standard | 2.5x standard |
| Token efficiency vs prior gen | not directly reported | 40% fewer tokens vs GPT-5.4 | 40% fewer tokens vs GPT-5.4 |
At list prices, Grok 4.3 is 4x cheaper on input and 12x cheaper on output than GPT-5.5 Standard. Versus GPT-5.5 Pro, the gap widens to 24x on input and 72x on output.
Two offsets narrow the practical gap:
GPT-5.5 token efficiency delivers 40% fewer tokens than GPT-5.4 on reasoning heavy tasks, which means a workload that previously cost X on GPT-5.4 costs roughly 0.6X on GPT-5.5 at the same per token rate. This is a meaningful effective discount.
Batch and Flex pricing cuts GPT-5.5 cost by 50% for non real time workloads. Effective rates land at $2.50 input and $15 output for batch jobs.
Even with both offsets applied, Grok 4.3 remains dramatically cheaper. The question is not whether Grok is cheaper. The question is whether the GPT-5.5 capability premium produces enough downstream value to justify the gap on your specific workload.
Direct Comparison Table
| Category | Grok 4.3 | GPT-5.5 | Edge |
|---|---|---|---|
| Agentic coding (Terminal-Bench, SWE-Bench Pro) | not directly reported | 82.7% / 58.6% | GPT |
| Computer use (OSWorld-Verified) | not directly reported | 78.7% | GPT |
| Frontier math | not directly reported | 35.4% Tier 4 | GPT |
| Intelligence Index | 53 | 60 | GPT |
| Legal / finance domain | strongest published | not directly reported | Grok |
| Native video input | yes | no | Grok |
| Context window | 1M | 1M | Tie |
| Input price (per 1M) | $1.25 | $5.00 / $30.00 (Pro) | Grok |
| Output price (per 1M) | $2.50 | $30.00 / $180.00 (Pro) | Grok |
| Token efficiency | not directly reported | 40% fewer than GPT-5.4 | GPT |
| Batch discount | not directly reported | 50% (Batch / Flex) | GPT |
Which One Should You Use
Use Grok 4.3 when:
- Cost per token is the dominant variable
- Native video input is a core requirement
- Your workload is legal research, financial analysis, or general professional knowledge work
- You can absorb the capability gap on agentic coding for a 4x to 12x price advantage
- You are building high volume generation pipelines where output token costs dominate
Use GPT-5.5 when:
- Agentic coding, computer use, or frontier math are central
- You need the highest published Terminal-Bench 2.0 and OSWorld-Verified scores
- Output quality compounds downstream into measurable business impact
- Token efficiency on reasoning heavy workloads offsets the higher per token rate
- You are already deep in the OpenAI or Azure ecosystem
Use GPT-5.5 Pro when:
- The hardest reasoning workloads justify a 24x premium over Grok 4.3 on input
- Your edge cases (complex categorization, formal proof style reasoning, novel domain transfer) require maximum cognitive depth
- The cost of a bad output massively dwarfs the API bill
Use both when:
- Grok 4.3 handles high volume generation, video processing, and legal or financial analysis
- GPT-5.5 handles complex agentic work, computer use automation, and hard reasoning
- Route by task shape rather than provider loyalty
Our Default for May 2026
For agentic coding, computer use, and frontier reasoning, GPT-5.5 is the strongest published option in this comparison. The Terminal-Bench 2.0 score at 82.7% and the OSWorld-Verified score at 78.7% are the highest disclosed numbers among production models.
For cost sensitive high volume workloads, video input pipelines, and legal or financial domain work, Grok 4.3 is the strongest option at its price tier. The 4x input and 12x output price gap to GPT-5.5 Standard is large enough that the routing decision becomes obvious on workloads that do not require top tier agentic capability.
A durable AI architecture in May 2026 uses Grok 4.3 where cost per token and video input matter most, and reaches for GPT-5.5 where agentic capability and output quality compound into downstream value. GPT-5.5 Pro stays reserved for the hardest reasoning edges where the price premium is justified by the workload shape.
How Contra Collective Bridges the Gap
Contra Collective runs Grok 4.3, GPT-5.5, Opus 4.7, Gemini 3.1 Pro, Gemma 4, and Qwen 3.6 in production across coding pipelines, multimodal content systems, and multi agent workflows for enterprise clients. We architect systems that use the right model at each stage rather than defaulting to a single provider. Ready to make the right call for your stack? Book a free technical audit, no sales pitch, just clarity.
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