Claude Sonnet 5 vs GPT-5.6
Pricing, benchmarks, and use case comparison
Verdict
Our pick: Claude Sonnet 5Pick Claude Sonnet 5 for a shipping, generally-available agentic coder with predictable $3/$15 pricing and a confirmed 1M context; pick the GPT-5.6 family if you are an approved preview partner who wants to route work across Sol, Terra, and Luna cost tiers.
Specs comparison
| Claude Sonnet 5 | GPT-5.6 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | ✓1M | Not announced |
| Input / 1M tokens | ✓$3.00 | 5 |
| Output / 1M tokens | $15.00 | 30 |
| Release date | 2026-06 | 2026-06 |
Benchmarks
| Benchmark | Claude Sonnet 5 | GPT-5.6 |
|---|---|---|
| SWE-bench Verified | ~85.2% | - |
| Terminal-Bench 2.1 | 80.4% | ✓88.8 |
| SWE-bench Pro | 63.2% | - |
| OSWorld-Verified | 81.2% | - |
| Terminal-Bench 2.1 (Sol) | - | 88.8% |
| Terminal-Bench 2.1 (Terra) | - | 82.5% |
| Terminal-Bench 2.1 (Luna) | - | 84.3% |
| ExploitBench | - | Competitive with Anthropic Mythos Preview |
| ExploitGym | - | Significant improvements |
| GeneBench v1 | - | Not announced |
Scores sourced from official provider release posts and independent benchmark aggregators.
Capability and benchmarks
Both are frontier-class, but they sit at different points on the intelligence curve. Claude Sonnet 5 scores 80.4% on Terminal-Bench 2.1, around 85.2% on SWE-bench Verified, and 63.2% on SWE-bench Pro. The GPT-5.6 family spans three tiers on Terminal-Bench 2.1: Sol at 88.8%, Luna at 84.3%, and Terra at 82.5%. On raw headroom, GPT-5.6 Sol is stronger, and even the Luna and Terra tiers edge Sonnet 5 on that one terminal benchmark. Sonnet 5's own capability scores (coding 92, reasoning 90) trail the family's flagship posture (coding 94, reasoning 94), so GPT-5.6 wins on ceiling.
Availability, price, and context
This is where Sonnet 5 pulls ahead for most teams. It is generally available today across the Claude API, Bedrock, Google Cloud, and Microsoft Foundry, with a documented 1M-token context and clear pricing: introductory $2/$10 per 1M through August 31, 2026, then $3/$15. GPT-5.6 is a government-coordinated limited preview gated to approved partners, with no single price or context window published for the family (specs are per tier: Sol $5/$30, Terra $2.50/$15, Luna $1/$6). If you need a stable model id and confirmed specs for production, Sonnet 5 is the safer bet.
- Sonnet 5: $3/$15 standard, 1M context, GA everywhere.
- GPT-5.6: per-tier pricing, context not announced, gated preview.
Which to pick
Pick Claude Sonnet 5 if you want to ship now: high-volume agent loops, large-codebase work needing a real 1M window, and near-Opus quality at a mid-tier price. Pick the GPT-5.6 family if you have preview access and want one generation you can split across Sol for the hardest reasoning, Terra for balance, and Luna for cheap high-volume calls, and you can tolerate an unconfirmed context window and gated access.
Which should you choose?
Choose Claude Sonnet 5 if...
- →You want frontier-adjacent agentic coding but need better cost-efficiency than Opus
- →You are running high-volume agent loops and want strong reasoning per dollar
- →You are already on Sonnet 4.6 and want a same-price capability upgrade
- →You need a 1M context window with fast latency
Choose GPT-5.6 if...
- →You want to standardize on one model generation but route requests across cost/quality tiers
- →You are an approved preview partner exploring the newest OpenAI capabilities
- →Workloads spanning agentic coding, knowledge work, and research where tier flexibility helps