Model comparison
GPT-5.1-Codex-Max vs GPT-5.5 Pro
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-5.1-Codex-Max #90 (Estimated); GPT-5.5 Pro #38 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.1-Codex-Max and GPT-5.5 Pro share 1 comparable benchmark result. 0 of 8 categories are comparable. 12 results are unique to GPT-5.1-Codex-Max; 6 to GPT-5.5 Pro.
Updated July 22, 2026- Shared results
- 1
- GPT-5.1-Codex-Max only
- 12
- GPT-5.5 Pro only
- 6
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.1-Codex-Max and GPT-5.5 Pro is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 1 shared benchmark result across 1 evidence category; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
GPT-5.5 Pro is priced at $30.00 input / $180.00 output per 1M tokens, versus $1.25 input / $10.00 output per 1M tokens for GPT-5.1-Codex-Max. GPT-5.5 Pro has the larger context window at 1M, compared with 400K for GPT-5.1-Codex-Max.
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-5.1-Codex-Max | Δ | GPT-5.5 Pro |
|---|---|---|---|
| Agentic | GPT-5.1-Codex-MaxNot measured | MarginNo overlap | GPT-5.5 Pro90.1 |
| Knowledge | GPT-5.1-Codex-MaxNot measured | MarginNo overlap | GPT-5.5 Pro57.2 |
| Math | GPT-5.1-Codex-MaxNot measured | MarginNo overlap | GPT-5.5 Pro48.1 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.1-Codex-Max | GPT-5.5 Pro | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.1-Codex-Max$1.25 input / $10 output | GPT-5.5 Pro$30 input / $180 output | GPT-5.1-Codex-Max has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.1-Codex-MaxNot available | GPT-5.5 ProNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.1-Codex-MaxNot available | GPT-5.5 ProNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.1-Codex-Max400K | GPT-5.5 Pro1M | GPT-5.5 Pro lists the larger context window. |
Benchmark Deep Dive
Agentic2 benchmarks
Coding2 benchmarks
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-5.5 Pro | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 34.7% | — | Not comparable |
| AA-GPQA DiamondSource | 86.0% | — | Not comparable |
| AA-HLESource | 23.4% | — | Not comparable |
| AA-Omniscience IndexSource | -6.0% | — | Not comparable |
| AA-Omniscience AccuracySource | 39.2% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 74.4% | — | Not comparable |
| HLESource | — | 57.2% | Not comparable |
| HLE w/o toolsSource | — | 43.1% | Not comparable |
Math3 benchmarks
Multimodal1 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-5.5 Pro | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 72.5% | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-5.5 Pro | Result |
|---|---|---|---|
| AA-IFBenchSource | 70.0% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare GPT-5.1-Codex-Max and GPT-5.5 Pro on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for GPT-5.1-Codex-Max and GPT-5.5 Pro today?
GPT-5.1-Codex-Max: $1.25 input / $10.00 output per 1M tokens GPT-5.5 Pro: $30.00 input / $180.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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