Standard Compute
Model comparison 2026

Claude Sonnet 5.5 vs GPT-5.6 Terra

Claude Sonnet 5.5
Anthropic · Balanced · Proprietary
$4.40/1M · 1M ctx
GPT-5.6 Terra
OpenAI · Balanced · Proprietary
$5.00/1M · 1.1M ctx

Community vote

Pick a winner in each dimension. You can change your vote any time.

Output Quality
Correctness and depth of what it produces
Agentic Ability
Tool calls, instruction-following, and multi-step tasks
Speed
Tokens per second and time-to-first-token
Value for money
How much capability you get per dollar
Reliability
Consistent results: fewer refusals, loops and format breaks

Specs and pricing side by side

Spec
Sonnet 5.5
GPT-5.6 Terra
Maker
Anthropic
OpenAI
Blended price / 1M
$4.40
$5.00
Input / output
$2.00 in · $10 out / 1M tokens
$2.00 in · $12 out / 1M tokens
Context window
1M
1.1M
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
9.8
9.0
Agentic Ability
9.8
9.0
Speed
8.4
8.4
Value for money
8.8
8.8
Reliability
9.4
9.2

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Sonnet 5.5 or GPT-5.6 Terra?

Updated 2026-10-13

Choose Claude Sonnet 5.5 if you want the everyday default for coding agents, escalating to Opus 5.5 only for the hardest tasks. Choose GPT-5.6 Terra if you want the everyday OpenAI default for agents — volume work with frontier-adjacent quality.

In our editorial scoring, Claude Sonnet 5.5 leads in 3 of five dimensions (output quality, agentic ability and reliability), while GPT-5.6 Terra leads in 0. On price, Claude Sonnet 5.5 runs about $4.40 per 1M tokens (blended) and is proprietary; GPT-5.6 Terra is about $5.00 and proprietary.

Where Sonnet 5.5 falls short
  • Artificial Analysis flags it as very verbose, which adds output tokens
  • Released September 2026, so its long-run track record is still short
Full Sonnet 5.5 breakdown →
Where GPT-5.6 Terra falls short
  • Steps behind Sol on the hardest tasks
  • GPT-6.1 Sol now costs about the same ($2/$10) and scores far higher
Full GPT-5.6 Terra breakdown →

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