Grok 4.5 vs GPT-5.5
SpaceXAI's brand-new value workhorse against OpenAI's shipping flagship — published pricing, context windows and specs, side by side.
Grok 4.5 vs GPT-5.5: side-by-side
| Grok 4.5 | GPT-5.5 | |
|---|---|---|
| Maker | SpaceXAI (formerly xAI) | OpenAI |
| Released | 9 July 2026 | 23 April 2026 |
| Tier | Workhorse ("Opus-class" positioning) | Flagship |
| Context window | 500,000 tokens | 1,000,000 tokens (400K in Codex CLI) |
| API price (per 1M) | $2 / $6 per 1M tokens | $5 / $30 per 1M tokens (Thinking) |
| Speed | ~80 output tokens/second | Not specified |
| Access | Proprietary — xAI API console, Grok Build, Cursor, OpenRouter · EU pending (later July 2026) | Proprietary — ChatGPT & Codex (Plus, Pro, Business, Enterprise) + API |
| Best at | Coding, office/clerical work, research at low cost per task | Agentic coding, computer use, deep research |
| Standout | Token efficiency — ~2x fewer tokens claimed vs leading models at the same tasks | First full retrain since GPT-4.5 — unified multimodal (text, images, audio, video) |
Price comparison
| Model | Input (per 1M) | Output (per 1M) |
|---|---|---|
| Grok 4.5 | $2.00 | $6.00 |
| GPT-5.5 (Thinking) | $5.00 | $30.00 |
| GPT-5.5 Pro | $30.00 | $180.00 |
Estimate your monthly API cost for Grok 4.5 vs GPT-5.5 with the LLM API pricing calculator →
Published benchmark figures
Each figure is the model's own published score as listed on its AI Model Hub page. Note the suite versions: GPT-5.5's own materials report Terminal-Bench 2.0, while SpaceXAI's Grok 4.5 chart used Terminal-Bench 2.1 (where it also plotted GPT-5.5 at 83.4%). Different suite versions are not directly comparable.
| Model | Benchmark | Published score |
|---|---|---|
| Grok 4.5 | Terminal-Bench 2.1 | 83.3% |
| Grok 4.5 | SWE-bench Pro | 64.7% |
| Grok 4.5 | DeepSWE 1.1 | 53% |
| GPT-5.5 | Terminal-Bench 2.0 | 82.7% |
| GPT-5.5 | GDPval | 84.9% |
| GPT-5.5 | Expert-SWE | 73.1% |
| GPT-5.5 | SWE-bench Pro | 58.6% |
| GPT-5.5 | FrontierMath Tier 4 | 35.4% |
What the table says
- Pricing. Grok 4.5 lists at $2 / $6 per 1M tokens; GPT-5.5 (Thinking) at $5 / $30. That is 2.5x cheaper input and 5x cheaper output — the widest price gap between any two current flagship-adjacent models on this site.
- Benchmarks. On terminal/agentic coding the two are effectively tied (83.3 vs 83.4 on SpaceXAI's TB 2.1 chart; GPT-5.5's own TB 2.0 figure is 82.7). On SWE-bench Pro, Grok 4.5's 64.7% actually tops GPT-5.5's published 58.6%. GPT-5.5 counters with breadth: GDPval, Expert-SWE and FrontierMath results plus mature multimodal support.
- Context. GPT-5.5 doubles Grok 4.5's window — 1M vs 500K tokens.
- Ecosystem. GPT-5.5 ships inside ChatGPT, Codex and a mature API; Grok 4.5 is brand-new, with EU access still pending.
Key takeaway
Grok 4.5 undercuts GPT-5.5 sharply on price while matching it on the agentic-coding benchmarks both have published; GPT-5.5 keeps the bigger context, broader benchmark record and deeper ecosystem. Run your own token volumes through the pricing calculator to see the monthly difference.
Full Grok 4.5 overview Full GPT-5.5 overview
Frequently asked questions
Which is cheaper, Grok 4.5 or GPT-5.5?
Grok 4.5 — $2 / $6 per 1M tokens versus $5 / $30 for GPT-5.5 (Thinking): 2.5x cheaper input, 5x cheaper output.
Which has the bigger context window?
GPT-5.5 — 1,000,000 tokens (400K in Codex CLI) versus 500,000 for Grok 4.5.
Which model is newer?
Grok 4.5 — released 9 July 2026; GPT-5.5 shipped 23 April 2026.
Can I run either locally?
No — both are proprietary, hosted-API models; neither publishes weights.