Model comparison
Claude Sonnet 5 vs GPT-5.6 Luna: Benchmark Comparison
Claude Sonnet 5 has the higher score on 12 of 27 shared benchmarks; GPT-5.6 Luna leads on 14.
The largest observed score gap is 17.00 pts on ProofBench v1.1 , where Claude Sonnet 5 leads.
Reported ±1 standard-error ranges overlap on 12 of 27 shared benchmarks with comparable uncertainty data. This is not a pairwise statistical significance test.
Shared benchmark results
Scores and reported standard errors come from the latest visible Vals benchmark version available for both models.
| Benchmark | Claude Sonnet 5 | GPT-5.6 Luna | Gap | Reported uncertainty |
|---|---|---|---|---|
| Vals Index | 51.77% ±1.09 | 51.69% ±1.06 | 0.09 pts | Reported ±1 SE ranges overlap |
| Harvey's Legal Agent Benchmark | 5.00% ±1.65 | 1.25% ±0.83 | 3.75 pts | Reported ±1 SE ranges do not overlap |
| Legal Research Bench | 41.83% ±3.43 | 36.54% ±3.35 | 5.29 pts | Reported ±1 SE ranges overlap |
| LegalBench | 83.92% ±0.46 | 84.03% ±0.42 | 0.11 pts | Reported ±1 SE ranges overlap |
| EMB | 66.32% ±3.01 | 67.12% ±2.94 | 0.80 pts | Reported ±1 SE ranges overlap |
| Finance Agent (v2) | 53.91% ±0.52 | 55.04% ±0.31 | 1.13 pts | Reported ±1 SE ranges do not overlap |
| MortgageTax | 70.03% ±0.90 | 67.29% ±0.92 | 2.74 pts | Reported ±1 SE ranges do not overlap |
| Tax Agent Bench | 62.27% ±3.19 | 60.81% ±3.26 | 1.46 pts | Reported ±1 SE ranges overlap |
| TaxEval v2 | 75.63% ±0.84 | 76.17% ±0.84 | 0.53 pts | Reported ±1 SE ranges overlap |
| MedCode | 47.54% ±2.27 | 42.39% ±2.27 | 5.15 pts | Reported ±1 SE ranges do not overlap |
| MedScribe | 76.05% ±3.05 | 84.39% ±2.58 | 8.34 pts | Reported ±1 SE ranges do not overlap |
| ProofBench v1.1 | 77.00% ±4.23 | 60.00% ±4.92 | 17.00 pts | Reported ±1 SE ranges do not overlap |
| Terminal-Bench Science | 2.86% ±2.01 | 0.00% ±0.00 | 2.86 pts | Reported ±1 SE ranges do not overlap |
| GPQA Diamond | 88.89% ±2.22 | 91.67% ±1.74 | 2.78 pts | Reported ±1 SE ranges overlap |
| MMLU Pro | 87.55% ±0.37 | 86.04% ±0.35 | 1.51 pts | Reported ±1 SE ranges do not overlap |
| MMMU Pro | 83.01% ±0.90 | 85.03% ±0.86 | 2.02 pts | Reported ±1 SE ranges do not overlap |
| SAGE | 48.92% ±3.40 | 44.22% ±3.33 | 4.70 pts | Reported ±1 SE ranges overlap |
| Code Migration | 44.39% ±4.25 | 44.55% ±4.24 | 0.16 pts | Reported ±1 SE ranges overlap |
| IOI | 45.00% ±2.75 | 61.78% ±11.61 | 16.78 pts | Reported ±1 SE ranges do not overlap |
| ProgramBench | 0.00% ±0.00 | 0.00% ±0.00 | 0.00 pts | Reported ±1 SE ranges overlap |
| SkillsBench | 46.48% ±4.49 | 60.45% ±4.75 | 13.97 pts | Reported ±1 SE ranges do not overlap |
| SWE-bench | 79.60% ±1.80 | 93.00% ±1.14 | 13.40 pts | Reported ±1 SE ranges do not overlap |
| Terminal-Bench 4.0 | 9.60% ±1.01 | 11.62% ±1.01 | 2.02 pts | Reported ±1 SE ranges overlap |
| Vibe Code Bench 1-100 | 13.82% ±2.98 | 22.59% ±4.00 | 8.77 pts | Reported ±1 SE ranges do not overlap |
| Vibe Code Bench v1.1 | 81.33% ±3.05 | 77.06% ±3.07 | 4.27 pts | Reported ±1 SE ranges overlap |
| CyberBench v1.1 | 61.91% ±5.74 | 73.63% ±5.56 | 11.73 pts | Reported ±1 SE ranges do not overlap |
| Public Benefits Bench v1.1 | 66.03% ±1.23 | 61.16% ±1.27 | 4.87 pts | Reported ±1 SE ranges do not overlap |
Performance by category
| Category | Claude Sonnet 5 average | GPT-5.6 Luna average |
|---|---|---|
| Legal | 43.58% | 40.61% |
| Finance | 65.63% | 65.29% |
| Healthcare | 61.80% | 63.39% |
| Math | 77.00% | 60.00% |
| Science | 2.86% | 0.00% |
| Academic | 86.48% | 87.58% |
| Education | 48.92% | 44.22% |
| Coding | 40.03% | 46.38% |
| Beta | 61.91% | 73.63% |
| Social Mobility | 66.03% | 61.16% |
Cost and latency
Cost per test appears only where the benchmark reports it for both models. Latency is the measured completion time for that benchmark.
| Benchmark | Claude Sonnet 5 cost | GPT-5.6 Luna cost | Claude Sonnet 5 latency | GPT-5.6 Luna latency |
|---|---|---|---|---|
| Vals Index | $13.72 | $0.82 | 54m16s | 29m27s |
| Harvey's Legal Agent Benchmark | $8.95 | $0.38 | 38m52s | 10m56s |
| Legal Research Bench | $2.72 | $0.85 | 25m46s | 39m34s |
| LegalBench | N/A | N/A | 4.90s | 5.89s |
| EMB | $10.29 | $0.37 | 49m46s | 11m00s |
| Finance Agent (v2) | $0.75 | $0.28 | 13m12s | 12m52s |
| MortgageTax | N/A | N/A | 28.67s | 22.84s |
| Tax Agent Bench | $1.79 | $0.47 | 19m19s | 42m46s |
| TaxEval v2 | N/A | N/A | 3m22s | 76.52s |
| MedCode | N/A | N/A | 2m15s | 81.28s |
| MedScribe | N/A | N/A | 4m12s | 116.89s |
| ProofBench v1.1 | $1.37 | $0.12 | 14m58s | 8m34s |
| Terminal-Bench Science | $18.70 | $0.58 | 2h55m | 2h03m |
| GPQA Diamond | N/A | N/A | 63.23s | 53.52s |
| MMLU Pro | N/A | N/A | 25.19s | 16.95s |
| MMMU Pro | N/A | N/A | 18.82s | 35.10s |
| SAGE | N/A | N/A | 7m14s | 51.88s |
| Code Migration | $35.31 | $1.88 | 1h57m | 58m35s |
| IOI | $12.89 | $0.58 | 59m44s | 1h10m |
| ProgramBench | $24.36 | $0.94 | 1h31m | 41m34s |
| SkillsBench | $2.90 | $0.21 | 15m12s | 5m20s |
| SWE-bench | $1.49 | $0.04 | 16m02s | 3m21s |
| Terminal-Bench 4.0 | $26.33 | $0.73 | 1h45m | 35m55s |
| Vibe Code Bench 1-100 | $71.15 | $4.91 | 4h16m | 2h03m |
| Vibe Code Bench v1.1 | $25.39 | $0.73 | 1h07m | 25m52s |
| CyberBench v1.1 | $1.89 | $0.40 | 16m57s | 16m15s |
| Public Benefits Bench v1.1 | $1.29 | $0.27 | 21m09s | 38m40s |
Results available only for Claude Sonnet 5
- LiveCodeBench
Results available only for GPT-5.6 Luna
- BioMysteryBench
- MysteryMechanism