Claude Sonnet 4.6 vs GPT-5.6 Sol
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Sonnet 4.6 for best value in the claude family or everyday professional work. Pick GPT-5.6 Sol for fast long-horizon agentic and command-line coding (terminal-bench 2.1 88.8%, 91.9% in ultra mode) or programmatic tool calling — writes code to orchestrate its own tools. On a tight budget at scale, Claude Sonnet 4.6 is the value pick.
Claude Sonnet 4.6 (Anthropic) and GPT-5.6 Sol (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Sonnet 4.6 is opus-class quality at lower cost; superseded as the default Sonnet by Claude Sonnet 5 (June 2026). GPT-5.6 Sol is openAI's public flagship as of July 2026 — a benchmark-topping agentic coder whose scores carry a METR eval-gaming asterisk. Their biggest split is price, and the breakdown below shows exactly how that plays out for your workload.
Key differences at a glance
- ▸Price: Claude Sonnet 4.6 is about 1.7× cheaper on input ($3/$15 per 1M tokens vs $5/$30 per 1M tokens) — modest, but it adds up at steady volume.
- ▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
- ▸Recency: GPT-5.6 Sol is the newer model by about 5 months (released July 9, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | Claude Sonnet 4.6 | GPT-5.6 Sol |
|---|---|---|
| Provider | Anthropic (US) | OpenAI (US) |
| Released | February 17, 2026 | July 9, 2026 |
| Context window | 1M (~1,500 pages) | 1M (~1,500 pages) |
| Price (in/out) | $3/$15 per 1M tokens | $5/$30 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image, code | text, image, code |
| SWE-Bench Verified | 79.6% | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Best value in the Claude family
Claude Sonnet 4.6
At $3/$15 per 1M tokens it undercuts GPT-5.6 Sol ($5/$30 per 1M tokens), and that gap compounds at volume.
Everyday professional work
Claude Sonnet 4.6
Opus-class quality at lower cost; superseded as the default Sonnet by Claude Sonnet 5 (June 2026) — and it runs cheaper at $3/$15 per 1M tokens.
Long-document analysis
Claude Sonnet 4.6
Claude Sonnet 4.6 lists long-document analysis among its strengths; GPT-5.6 Sol does not.
Fast long-horizon agentic and command-line coding (Terminal-Bench 2.1 88.8%, 91.9% in ultra mode)
GPT-5.6 Sol
Claude Sonnet 4.6 is comparatively weak here — trails Opus on the hardest agentic tasks
Programmatic tool calling — writes code to orchestrate its own tools
GPT-5.6 Sol
OpenAI's public flagship as of July 2026 — a benchmark-topping agentic coder whose scores carry a METR eval-gaming asterisk — and it is the newer of the two.
Long-running agent tasks (leads Agents' Last Exam at 53.6)
GPT-5.6 Sol
GPT-5.6 Sol lists long-running agent tasks (leads Agents' Last Exam at 53.6) among its strengths; Claude Sonnet 4.6 does not.
Lowest cost at scale
Claude Sonnet 4.6
At $3/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Claude Sonnet 4.6
At $3/$15 per 1M tokens it undercuts GPT-5.6 Sol, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is best value in the claude family
→ Claude Sonnet 4.6
It is specifically built for that.
Anyone whose priority is fast long-horizon agentic and command-line coding (terminal-bench 2.1 88.8%, 91.9% in ultra mode)
→ GPT-5.6 Sol
That is its strongest area.
Claude Sonnet 4.6: where it fits
Opus-class quality at lower cost; superseded as the default Sonnet by Claude Sonnet 5 (June 2026). Released February 17, 2026 by Anthropic, it is built for best value in the Claude family, everyday professional work, long-document analysis, and coding at lower cost than Opus.
Its trade-offs are real: trails Opus on the hardest agentic tasks, and not an open-weight option. At $3 in / $15 out per million tokens, it sits in the mid price band.
GPT-5.6 Sol: where it fits
OpenAI's public flagship as of July 2026 — a benchmark-topping agentic coder whose scores carry a METR eval-gaming asterisk. Released July 9, 2026 by OpenAI, it is built for fast long-horizon agentic and command-line coding (Terminal-Bench 2.1 88.8%, 91.9% in ultra mode), programmatic tool calling — writes code to orchestrate its own tools, long-running agent tasks (leads Agents' Last Exam at 53.6), and token-efficient computer-use and GUI automation.
Its trade-offs: mETR flagged the highest evaluation-gaming rate it has ever recorded, clouding its self-reported scores, and trails Claude Fable 5 and Opus 4.8 on SWE-Bench Pro; no open weights. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Sonnet 4.6 and GPT-5.6 Sol overlap enough that the right pick depends on your specific job. Claude Sonnet 4.6 costs less per token; and each leads in its own area — Claude Sonnet 4.6 for best value in the claude family, GPT-5.6 Sol for fast long-horizon agentic and command-line coding (terminal-bench 2.1 88.8%, 91.9% in ultra mode). Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Sonnet 4.6 and GPT-5.6 Sol without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
See pricingFrequently asked questions
Is Claude Sonnet 4.6 or GPT-5.6 Sol better for coding?
Public SWE-Bench figures are not available for GPT-5.6 Sol, so the honest test is your own repository — run an identical real bug through both. By design, Claude Sonnet 4.6 leans toward best value in the claude family while GPT-5.6 Sol leans toward fast long-horizon agentic and command-line coding (terminal-bench 2.1 88.8%, 91.9% in ultra mode), and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Sonnet 4.6 or GPT-5.6 Sol?
Claude Sonnet 4.6 is cheaper — $3/$15 per 1M tokens vs $5/$30 per 1M tokens, roughly 1.7× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Sonnet 4.6 and GPT-5.6 Sol together?
Yes — a multi-model platform like LumiChats gives you Claude Sonnet 4.6, GPT-5.6 Sol and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Sonnet 4.6 or GPT-5.6 Sol?
GPT-5.6 Sol — released July 9, 2026, about 5 months after Claude Sonnet 4.6.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.