Claude Opus 4.8 vs GPT-5.6 Terra: Benchmark Comparison
Claude Opus 4.8 has the higher score on 17 of 24 shared benchmarks; GPT-5.6 Terra leads on 7.
The largest observed score gap is 9.80 pts on MedCode , where Claude Opus 4.8 leads.
Reported ±1 standard-error ranges overlap on 15 of 24 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 Opus 4.8 | GPT-5.6 Terra | Gap | Reported uncertainty |
|---|---|---|---|---|
| Vals Index | 55.10% ±1.01 | 53.09% ±1.29 | 2.02 pts | Reported ±1 SE ranges overlap |
| Harvey's Legal Agent Benchmark | 9.58% ±2.15 | 0.83% ±0.83 | 8.75 pts | Reported ±1 SE ranges do not overlap |
| Legal Research Bench | 43.75% ±3.45 | 41.35% ±3.42 | 2.40 pts | Reported ±1 SE ranges overlap |
| LegalBench | 83.57% ±0.47 | 85.11% ±0.45 | 1.54 pts | Reported ±1 SE ranges do not overlap |
| EMB | 69.37% ±2.61 | 66.20% ±3.11 | 3.17 pts | Reported ±1 SE ranges overlap |
| Finance Agent (v2) | 53.92% ±0.16 | 54.44% ±2.07 | 0.52 pts | Reported ±1 SE ranges overlap |
| MortgageTax | 69.91% ±0.89 | 67.33% ±0.93 | 2.58 pts | Reported ±1 SE ranges do not overlap |
| Tax Agent Bench | 64.91% ±3.17 | 65.20% ±3.19 | 0.29 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 | 53.22% ±2.17 | 43.41% ±2.17 | 9.80 pts | Reported ±1 SE ranges do not overlap |
| MedScribe | 85.75% ±1.93 | 82.87% ±1.95 | 2.89 pts | Reported ±1 SE ranges overlap |
| Terminal-Bench Science | 4.29% ±2.44 | 10.00% ±3.61 | 5.71 pts | Reported ±1 SE ranges overlap |
| GPQA Diamond | 92.42% ±1.98 | 90.91% ±1.91 | 1.52 pts | Reported ±1 SE ranges overlap |
| MMLU Pro | 89.58% ±0.30 | 86.66% ±0.33 | 2.93 pts | Reported ±1 SE ranges do not overlap |
| MMMU Pro | 86.59% ±0.82 | 86.47% ±0.82 | 0.12 pts | Reported ±1 SE ranges overlap |
| SAGE | 54.79% ±3.35 | 47.00% ±3.40 | 7.78 pts | Reported ±1 SE ranges do not overlap |
| Code Migration | 47.25% ±4.18 | 47.80% ±4.28 | 0.55 pts | Reported ±1 SE ranges overlap |
| LiveCodeBench | 87.82% ±0.95 | 85.93% ±1.02 | 1.89 pts | Reported ±1 SE ranges overlap |
| ProgramBench | 1.00% ±0.70 | 0.50% ±0.50 | 0.50 pts | Reported ±1 SE ranges overlap |
| SkillsBench | 59.23% ±4.50 | 58.90% ±4.47 | 0.33 pts | Reported ±1 SE ranges overlap |
| SWE-bench | 88.60% ±1.42 | 95.40% ±0.94 | 6.80 pts | Reported ±1 SE ranges do not overlap |
| Terminal-Bench 4.0 | 23.23% ±1.34 | 22.73% ±2.31 | 0.50 pts | Reported ±1 SE ranges overlap |
| Vibe Code Bench v1.1 | 82.72% ±3.08 | 74.59% ±4.20 | 8.13 pts | Reported ±1 SE ranges do not overlap |
| Public Benefits Bench v1.1 | 68.13% ±1.21 | 62.38% ±1.26 | 5.75 pts | Reported ±1 SE ranges do not overlap |
Performance by category
| Category | Claude Opus 4.8 average | GPT-5.6 Terra average |
|---|---|---|
| Legal | 45.63% | 42.43% |
| Finance | 66.75% | 65.87% |
| Healthcare | 69.49% | 63.14% |
| Science | 4.29% | 10.00% |
| Academic | 89.53% | 88.01% |
| Education | 54.79% | 47.00% |
| Coding | 55.69% | 55.12% |
| Social Mobility | 68.13% | 62.38% |
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 Opus 4.8 cost | GPT-5.6 Terra cost | Claude Opus 4.8 latency | GPT-5.6 Terra latency |
|---|---|---|---|---|
| Vals Index | $13.14 | $5.78 | 39m48s | 35m39s |
| Harvey's Legal Agent Benchmark | $10.22 | $3.20 | 24m08s | 17m05s |
| Legal Research Bench | $2.82 | $7.91 | 11m54s | 1h10m |
| LegalBench | N/A | N/A | 3.11s | 2.78s |
| EMB | $12.06 | $2.19 | 43m52s | 13m33s |
| Finance Agent (v2) | $4.22 | $3.63 | 9m07s | 24m10s |
| MortgageTax | N/A | N/A | 20.81s | 6.32s |
| Tax Agent Bench | $1.69 | $4.83 | 7m59s | 1h01m |
| TaxEval v2 | N/A | N/A | 70.33s | 37.28s |
| MedCode | N/A | N/A | 105.92s | 18.41s |
| MedScribe | N/A | N/A | 82.36s | 35.53s |
| Terminal-Bench Science | $23.14 | $5.19 | 1h55m | 2h04m |
| GPQA Diamond | N/A | N/A | 2m14s | 36.76s |
| MMLU Pro | N/A | N/A | 23.44s | 8.17s |
| MMMU Pro | N/A | N/A | 49.04s | 13.03s |
| SAGE | N/A | N/A | 3m06s | 40.06s |
| Code Migration | $30.51 | $8.13 | 1h15m | 48m34s |
| LiveCodeBench | N/A | N/A | 2m40s | 44.33s |
| ProgramBench | $31.27 | $5.38 | 1h32m | 33m36s |
| SkillsBench | $4.77 | $1.75 | 15m30s | 6m55s |
| SWE-bench | $1.92 | $0.40 | 9m27s | 3m00s |
| Terminal-Bench 4.0 | $17.14 | $5.60 | 1h11m | 31m29s |
| Vibe Code Bench v1.1 | $26.88 | $7.89 | 1h16m | 19m12s |
| Public Benefits Bench v1.1 | $1.89 | $1.20 | 12m48s | 19m31s |
Results available only for Claude Opus 4.8
- Vals RSI Index
- Time Horizon Index: KSP
Results available only for GPT-5.6 Terra
- ProofBench v1.1
- IOI
- Vibe Code Bench 1-100
- CyberBench v1.1