GPT-5.6 Sol vs Claude Sonnet 5
OpenAI's GPT-5.6 Sol and Anthropic's Claude Sonnet 5 both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Claude Sonnet 5 is the cheaper option — roughly 2.0x less on a blended workload, and it suits fast claude-quality reasoning at scale. GPT-5.6 Sol justifies its premium when you need frontier coding and long-horizon agents.
OpenAI • GPT-5.6
$4.00 / $20.00
/ 1M tokens (input / output)
OpenAI's flagship tier and the current state of the art on agentic coding benchmarks. Reasoning effort is tunable from none through max, and an `ultra` setting coordinates parallel subagents across workstreams. Sol reaches near-Fable-5 intelligence while spending markedly fewer output tokens, which is why its cost per finished task lands well below its sticker price.
Anthropic • Claude 5
$2.00 / $10.00
/ 1M tokens (input / output)
The workhorse Claude tier: a full million tokens of context and adaptive thinking at $2/$10, which undercuts the previous Sonnet 4.6 generation by a third on input while raising the context ceiling fivefold. The default pick for latency-sensitive products that still want Claude's writing and tool-use behaviour.
Input price
Claude Sonnet 5 is 50% cheaper than GPT-5.6 Sol on input tokens.
Output price
Claude Sonnet 5 is 50% cheaper than GPT-5.6 Sol on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | GPT-5.6 Sol | Claude Sonnet 5 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $8 | $4 | $4 |
| Moderate — 10M in / 2M out | $80 | $40 | $40 |
| Heavy — 100M in / 20M out | $800 | $400 | $400 |
Specification comparison
| Attribute | GPT-5.6 Sol | Claude Sonnet 5 |
|---|---|---|
| Input (/ 1M tokens) | $4.00 | $2.00 |
| Output (/ 1M tokens) | $20.00 | $10.00 |
| Cached input | $0.40 | $0.20 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2026-01 |
| Relative latency | high | low |
| Open weights | No | No |
| API model ID | gpt-5.6-sol | claude-sonnet-5 |
| Status | stable | stable |
GPT-5.6 Sol: Promotional pricing (down from $5/$30) held at least through 2026-11-21. Prompts above 272K input tokens bill at higher rates; 'fast' processing is 2x.
Choose GPT-5.6 Sol if…
- Long-running autonomous coding agents
- Large-scale refactors and migrations
- Agentic browsing and computer use
- Scientific and financial analysis
Choose Claude Sonnet 5 if…
- Production chat and copilots
- Long-document analysis
- Tool-heavy agents needing fast turns
- Code review and PR automation
Frequently asked
Is GPT-5.6 Sol or Claude Sonnet 5 cheaper?
Claude Sonnet 5 is cheaper. On a blended 3:1 input-to-output workload it costs about 2.0x less than GPT-5.6 Sol.
Which has the larger context window, GPT-5.6 Sol or Claude Sonnet 5?
GPT-5.6 Sol has the larger window at 1.05M tokens versus 1M.
Should I use GPT-5.6 Sol or Claude Sonnet 5?
Pick GPT-5.6 Sol for frontier coding and long-horizon agents. Pick Claude Sonnet 5 for fast claude-quality reasoning at scale. If cost dominates the decision, Claude Sonnet 5 wins; if you need the capability ceiling, benchmark both on your own evals before committing.