text model comparison
GPT-5.6 Luna vs GPT-5.6 Terra
GPT-5.6 Luna and GPT-5.6 Terra are both current text models, from OpenAI. GPT-5.6 Luna is 90% cheaper per 1M input tokens than GPT-5.6 Terra, $0.20 vs $2. On Arena Text, GPT-5.6 Luna scores 1452 Elo and GPT-5.6 Terra 1466 Elo (Arena, measured October 8, 2026). Both accept 1,050,000 tokens of context.
Data verified October 12, 2026 · Dataset 2026-10-12
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | GPT-5.6 Luna | GPT-5.6 Terra |
|---|---|---|
| Price per 1M input tokens | $0.20 (better) | $2 |
| Price per 1M output tokens | $1.20 (better) | $12 |
| Cost of 10M input and 2M output tokens | $4.40 (better) | $44 |
| Arena Text | 1452 Elo (#29 of 39) | 1466 Elo (#23 of 39) (better) |
| GPQA Diamond | 91.6% (#19 of 37) | 93.3% (#13 of 37) (better) |
| FrontierMath Tiers 1-3 (v2) | 82.1% (#12 of 37) | 86% (#9 of 37) (better) |
| SimpleQA Verified | 41% (#26 of 34) | 43.2% (#24 of 34) (better) |
| Provider | OpenAI | OpenAI |
| Release date | July 9, 2026 | July 9, 2026 |
| Access | API only | API only |
| Context window | 1,050,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Input | text, image | text, image |
| Output | text | text |
When to choose each
GPT-5.6 Luna
Best for
- High-volume API evaluation with published low token prices
- Subagents and batch reasoning where cost per call dominates
Watch out for
- Not in the pinned LiveBench snapshot; its independent scores here come from Epoch AI's own GPQA Diamond, FrontierMath and SimpleQA Verified runs
GPT-5.6 Terra
Best for
- Balanced long-context API evaluations
- Reasoning-heavy work that does not depend on broad factual recall
Watch out for
- Not in the pinned LiveBench snapshot; its independent scores here come from Epoch AI's own GPQA Diamond, FrontierMath and SimpleQA Verified runs
GPT-5.6 Luna vs GPT-5.6 Terra FAQ
Which is cheaper, GPT-5.6 Luna or GPT-5.6 Terra?
GPT-5.6 Luna is 90% cheaper per 1M input tokens than GPT-5.6 Terra, $0.20 vs $2. For 10M input and 2M output tokens, GPT-5.6 Luna costs $4.40 and GPT-5.6 Terra $44 at standard rates.
Which scores higher on independent benchmarks, GPT-5.6 Luna or GPT-5.6 Terra?
GPT-5.6 Terra leads on Arena Text, 1466 Elo to 1452 Elo; GPT-5.6 Terra leads on GPQA Diamond, 93.3% to 91.6%; GPT-5.6 Terra leads on FrontierMath Tiers 1-3 (v2), 86% to 82.1%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, GPT-5.6 Luna or GPT-5.6 Terra?
Both accept 1,050,000 tokens of context.
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Production evaluation
Choosing between GPT-5.6 Luna and GPT-5.6 Terra?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty