Model comparison · Updated May 2026
GPT-5.5 vs Grok 4: Price, Context, Benchmarks (2026)
A direct, dated comparison of GPT-5.5 (OpenAI) and Grok 4 (xAI). Every number below is sourced from official provider docs and public benchmarks. If you need to make this decision today, the verdict is at the top.
30-second verdict
- Cheaper: Grok 4 (input $3.00 vs $5.00 per 1M tokens).
- Longer context: GPT-5.5 at 1.1M vs 256K.
- Stronger on SWE-bench Verified: GPT-5.5 (~65% vs ~55%).
- Higher LMArena: GPT-5.5 (1442 vs 1400).
Specs side-by-side
| Spec | GPT-5.5 | Grok 4 |
|---|---|---|
| Vendor | OpenAI | xAI |
| Input price (per 1M tokens) | $5.00 | $3.00 |
| Output price | $30.00 | $15.00 |
| Context window | 1.1M | 256K |
| Release date | 2026-04-23 | 2025-07-09 |
| SWE-bench Verified | ~65% | ~55% |
| HumanEval | ~96% | ~90% |
| LMArena (approx) | 1442 | 1400 |
| Open weights | No | No |
| Capabilities | reasoning, code, vision | reasoning, web |
Pricing from official OpenAI and xAI docs. Benchmark numbers from SWE-bench Verified, HumanEval, and LMArena public leaderboards as of May 2026.
GPT-5.5 — strengths and weaknesses
Strengths. Frontier reasoning, broad ecosystem, strong tool use, multimodal in/out.
Weaknesses. Premium pricing, occasional over-editing in agent loops.
Best for. Hard reasoning, ambiguous specs, system design, agent planners.
Grok 4 — strengths and weaknesses
Strengths. Real-time X/Twitter access, strong math, edgy persona.
Weaknesses. Thin IDE/tool ecosystem, weaker code than Claude/GPT-5.
Best for. Breaking news, social analysis, math, X-integrated workflows.
Which one should you pick?
Pick GPT-5.5 if: hard reasoning, ambiguous specs, system design, agent planners.
Pick Grok 4 if: breaking news, social analysis, math, x-integrated workflows.
Use both if: you're building an agent or content pipeline. Route the high-stakes / hard-reasoning calls to whichever scores higher on the axis you care about, and the bulk / cheap calls to the other. Most production AI products run a 2-3 model router rather than betting on one.
Try them side-by-side
The Check.AI comparison tool lets you put both models in one table with all the numbers, switch capability filters, and share the resulting URL with your team.