Standard Compute
Model comparison 2026

GPT-5.6 Terra vs GPT-6 Luna

GPT-5.6 Terra
OpenAI · Balanced · Proprietary
$5.00/1M · 1.1M ctx
GPT-6 Luna
OpenAI · Budget · Proprietary
$0.22/1M · 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
GPT-5.6 Terra
GPT-6 Luna
Maker
OpenAI
OpenAI
Blended price / 1M
$5.00
$0.22
Input / output
$2.00 in · $12 out / 1M tokens
$0.10 in · $0.50 out / 1M tokens
Context window
1.1M
1.1M
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
9.0
8.7
Agentic Ability
9.0
8.5
Speed
8.4
9.3
Value for money
8.8
9.4
Reliability
9.2
9.1

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

Verdict: GPT-5.6 Terra or GPT-6 Luna?

Updated 2026-10-13

Choose GPT-5.6 Terra if you want the everyday OpenAI default for agents — volume work with frontier-adjacent quality. Choose GPT-6 Luna if you want cheap, fast subtasks, routing and subagents in OpenAI-based stacks.

In our editorial scoring, GPT-5.6 Terra leads in 3 of five dimensions (output quality, agentic ability and reliability), while GPT-6 Luna leads in 2. On price, GPT-5.6 Terra runs about $5.00 per 1M tokens (blended) and is proprietary; GPT-6 Luna is about $0.22 and proprietary.

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 →
Where GPT-6 Luna falls short
  • Weak on long agentic runs (16.4% on Terminal-Bench 4.0)
  • Clear quality step below GPT-6.1 Sol
Full GPT-6 Luna breakdown →

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