Model comparison
GPT-5.5 Pro vs Grok 4.20
Head-to-head evidence from 1 shared benchmark result across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.5 Pro #38 (Estimated); Grok 4.20 #88 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.5 Pro and Grok 4.20 share 1 comparable benchmark result. 1 of 8 categories are comparable. 6 results are unique to GPT-5.5 Pro; 17 to Grok 4.20.
Updated July 22, 2026- Shared results
- 1
- GPT-5.5 Pro only
- 6
- Grok 4.20 only
- 17
- Comparable categories
- 1 / 8
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if you want the cheaper token bill or you need the larger 2M context window.
Confidence note. This is a partial-evidence comparison with 1 shared benchmark result across 1 evidence category; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GPT-5.5 Pro is clearly ahead on the BenchAlign aggregate, 63.69 to 54.68. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro's sharpest advantage is in agentic, where it averages 90.1 against 47.1.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. That is roughly 30.0x on output cost alone. Grok 4.20 gives you the larger context window at 2M, compared with 1M for GPT-5.5 Pro.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | GPT-5.5 Pro | Δ | Grok 4.20 |
|---|---|---|---|
| Agentic | GPT-5.5 Pro90.1 | Margin← 43.0 | Grok 4.2047.1 |
| Coding | GPT-5.5 ProNot measured | MarginNo overlap | Grok 4.2067.1 |
| Reasoning | GPT-5.5 ProNot measured | MarginNo overlap | Grok 4.2053.3 |
| Knowledge | GPT-5.5 Pro57.2 | MarginNo overlap | Grok 4.20Not measured |
| Math | GPT-5.5 Pro48.1 | MarginNo overlap | Grok 4.20Not measured |
| Multimodal | GPT-5.5 ProNot measured | MarginNo overlap | Grok 4.2070.1 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.5 Pro | Grok 4.20 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.5 Pro$30 input / $180 output | Grok 4.20$2 input / $6 output | Grok 4.20 has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.5 ProNot available | Grok 4.20233 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.5 ProNot available | Grok 4.2010.33 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.5 Pro1M | Grok 4.202M | Grok 4.20 lists the larger context window. |
Benchmark Deep Dive
AgenticGPT-5.5 Pro wins4 benchmarks
Coding4 benchmarks
Reasoning2 benchmarks
Knowledge5 benchmarks
Math3 benchmarks
Frequently Asked Questions (2)
Which is better, GPT-5.5 Pro or Grok 4.20?
GPT-5.5 Pro is ahead on BenchLM's BenchAlign leaderboard, 63.69 to 54.68.
Which is better for agentic tasks, GPT-5.5 Pro or Grok 4.20?
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 47.1. Grok 4.20 stays close enough that the answer can still flip depending on your workload.
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