Grok 4 vs GPT-5.5
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by xAI
|
by OpenAI
|
|---|---|---|
| Overview | ||
| Status | Retired flagship | Current flagship |
| Released | Jul 9, 2025 | Nov 15, 2025 |
| Pricing per million tokens | ||
| Input | $3.00/Mtok | $5.00/Mtok |
| Output | $15.00/Mtok | $30.00/Mtok |
| Blended avg | $6.00/Mtok | $11.25/Mtok |
| Cached input | — | $0.500/Mtok |
| Specifications | ||
| Context window | 256K tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimageaudio
|
| Benchmarks source: Vellum LLM Leaderboard | ||
| Avg benchmark score | 63 | 75 |
| Perf / dollar | 10.5 | 6.7 |
| GPQA Diamond | 87.5 | 93.6 |
| Terminal-Bench 2.1 | 27.2 | 82.7 |
| Humanity's Last Exam | 25.4 | 41.4 |
| ARC-AGI 2 | 16 | 85 |
| HumanEval | 75 | 58.6 |
| SWE-Bench Verified | 55 | — |
| LiveCodeBench | 79 | — |
| MCP Atlas | — | 75.3 |
| BrowseComp | — | 84.4 |
| OSWorld-Verified | — | 78.7 |
| AIME 2025 | 91.7 | — |
| MMMLU | 82 | — |
| BFCL | 72 | — |
| MATH 500 | 82 | — |
| AutoBench | — | 12.9 |
| Independent composite scores each on its own scale — not part of the average above | ||
| LMSYS Chatbot Arena | 1409.3 ELO | 1476.7 ELO |
| AA Intelligence Index | — | 56.3 |
| AA Agentic Index | — | 47.4 |
| AA-Omniscience Index (−100–100) | — | 20.5 |
| GDPval-AA v2 | — | 1491.1 ELO |
| Providers | ||
| Available from |
xAI — $3.00/$15.00/Mtok
|
OpenAI — $5.00/$30.00/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Grok 4 | GPT-5.5 | Savings |
|---|---|---|---|
| 1M tokens | $6 | $11.25 | $5.25 (46.7%) |
| 10M tokens | $60 | $112.5 | $52.5 (46.7%) |
| 100M tokens | $600 | $1125 | $525 (46.7%) |
| 1000M tokens | $6000 | $11250 | $5250 (46.7%) |
When to pick which
distilled from the pricing and spec data above- cost dominates: $6.00/Mtok blended vs $11.25 — 46.7% less on the same 50/50 token mix
- your workload re-reads context (agents, RAG, long chats): cached input costs $0.500/Mtok — 90% off its list input price, a discount Grok 4 doesn't offer
- you need the longer context: 1M tokens vs 256K (4.1×)
- raw capability matters more than price: 75 vs 63 average benchmark score
The cheaper option here — Grok 4 costs $6.00/Mtok blended on xAI.
Summary
Grok 4 by xAI costs $3.00/Mtok input and $15.00/Mtok output, with a 256K-token context window. It supports text, image input.
GPT-5.5 by OpenAI costs $5.00/Mtok input and $30.00/Mtok output, with a 1M-token context window. It supports text, image, audio input.
On a blended cost basis, Grok 4 is 46.7% cheaper than GPT-5.5.
On benchmarks, GPT-5.5 scores higher (75 vs 63) on average. In terms of value, Grok 4 has better performance per dollar (10.5 vs 6.7).
Note: Pricing is per million tokens. Actual costs vary with usage patterns, prompt caching, and batch discounts. Always verify against official provider pricing pages.