Model comparison
Claude Sonnet 4.5 vs GPT-5.1
Head-to-head evidence from 4 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Sonnet 4.5 #96 (Estimated); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Sonnet 4.5 and GPT-5.1 share 4 comparable benchmark results. 1 of 8 categories are comparable. 8 results are unique to Claude Sonnet 4.5; 17 to GPT-5.1.
Updated July 20, 2026- Shared results
- 4
- Claude Sonnet 4.5 only
- 8
- GPT-5.1 only
- 17
- Comparable categories
- 1 / 8
Pick GPT-5.1 if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 4 shared benchmark results across 3 evidence categories; 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-5.1 has the cleaner BenchAlign overall profile here, landing at 53.65 versus 53.61. It is a real lead, but still close enough that category-level strengths matter more than the headline number.
GPT-5.1's sharpest advantage is in mathematics, where it averages 26.4 against 11.2. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 13.495% to 31.034%.
Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $1.25 input / $10.00 output per 1M tokens for GPT-5.1. GPT-5.1 is the reasoning model in the pair, while Claude Sonnet 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.
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 | Claude Sonnet 4.5 | Δ | GPT-5.1 |
|---|---|---|---|
| Math | Claude Sonnet 4.511.2 | Margin→ 15.2 | GPT-5.126.4 |
| Agentic | Claude Sonnet 4.555.4 | MarginNo overlap | GPT-5.1Not measured |
| Coding | Claude Sonnet 4.577.2 | MarginNo overlap | GPT-5.1Not measured |
| Reasoning | Claude Sonnet 4.513.6 | MarginNo overlap | GPT-5.1Not measured |
| Knowledge | Claude Sonnet 4.583.4 | MarginNo overlap | GPT-5.1Not measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 13.495%B 31.034%Winner: GPT-5.1Δ 17.5FrontierMath v2 (Tiers 1-3): Claude Sonnet 4.5 scored 13.495%; GPT-5.1 scored 31.034%. GPT-5.1 wins this benchmark. - Source ↗
FrontierMath v2 (Tier 4)
MathA 4.167%B 12.500%Winner: GPT-5.1Δ 8.3FrontierMath v2 (Tier 4): Claude Sonnet 4.5 scored 4.167%; GPT-5.1 scored 12.500%. GPT-5.1 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Sonnet 4.5 | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Sonnet 4.5$3 input / $15 output | GPT-5.1$1.25 input / $10 output | GPT-5.1 has the lower combined listed price. |
| Generation speedtokens per second | Claude Sonnet 4.5Not available | GPT-5.1111 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Sonnet 4.5Not available | GPT-5.157.47 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Sonnet 4.5200K | GPT-5.1200K | Listed context windows are equal. |
Benchmark Deep Dive
Agentic9 benchmarks
| Benchmark | Claude Sonnet 4.5 | GPT-5.1 | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 50% | — | Not comparable |
| OSWorld-VerifiedSource | 61.4% | — | Not comparable |
| VITA-BenchSource | 17.0% | — | Not comparable |
| Gert LabsSource | 48.51% | 41.24% | Claude Sonnet 4.5 leads |
| JobBenchSource | 27.7% | — | Not comparable |
| AA Agentic IndexSource | — | 21.0% | Not comparable |
| τ²-bench resultsSource | — | 81.9% | Not comparable |
| GDPval-AASource | — | 24.4% | Not comparable |
| GDPval-AASource | — | 987 | Not comparable |
Coding4 benchmarks
Reasoning3 benchmarks
Knowledge7 benchmarks
| Benchmark | Claude Sonnet 4.5 | GPT-5.1 | Result |
|---|---|---|---|
| GPQASource | 83.4% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 36.9% | Not comparable |
| AA-GPQA DiamondSource | — | 87.3% | Not comparable |
| AA-HLESource | — | 26.5% | Not comparable |
| AA-Omniscience IndexSource | — | 5.6% | Not comparable |
| AA-Omniscience AccuracySource | — | 37.6% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 51.3% | Not comparable |
MathGPT-5.1 wins3 benchmarks
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude Sonnet 4.5 | GPT-5.1 | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 72.9% | Not comparable |
Frequently Asked Questions (2)
Which is better, Claude Sonnet 4.5 or GPT-5.1?
GPT-5.1 is ahead on BenchLM's BenchAlign leaderboard, 53.65 to 53.61. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 13.495% and 31.034%.
Which is better for math, Claude Sonnet 4.5 or GPT-5.1?
GPT-5.1 has the edge for math in this comparison, averaging 26.4 versus 11.2. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.
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