text model comparison
GLM-5.3-Flash vs GPT-5.6 Luna
GLM-5.3-Flash and GPT-5.6 Luna are both current text models, from Z.ai and OpenAI. GLM-5.3-Flash is 25% cheaper per 1M input tokens than GPT-5.6 Luna, $0.15 vs $0.20. On Arena Text, GLM-5.3-Flash scores 1475 Elo and GPT-5.6 Luna 1452 Elo (Arena, measured October 8, 2026). GPT-5.6 Luna has the larger context window, 1,050,000 vs 1,000,000 tokens.
Data verified October 13, 2026 · Dataset 2026-10-13
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | GLM-5.3-Flash | GPT-5.6 Luna |
|---|---|---|
| Price per 1M input tokens | $0.15 (better) | $0.20 |
| Price per 1M output tokens | $0.50 (better) | $1.20 |
| Cost of 10M input and 2M output tokens | $2.50 (better) | $4.40 |
| Arena Text | 1475 Elo (#21 of 49) (better) | 1452 Elo (#34 of 49) |
| GPQA Diamond | 90.2% (#27 of 40) | 91.6% (#20 of 40) (better) |
| FrontierMath Tiers 1-3 (v2) | 55.8% (#31 of 40) | 82.1% (#12 of 40) (better) |
| SimpleQA Verified | Not measured | 41% (#27 of 36) |
| Provider | Z.ai | OpenAI |
| Release date | August 26, 2026 | July 9, 2026 |
| Access | API and open weights | API only |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Input | text, image, video | text, image |
| Output | text | text |
When to choose each
GLM-5.3-Flash
Best for
- Low-cost coding from screenshots or screen recordings
- Document and research agents on a budget
Watch out for
- Thinking cannot be disabled
- A faster GLM-5.3-FlashX is a separate model id at $0.37 input and $1.25 output per 1M tokens
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
GLM-5.3-Flash vs GPT-5.6 Luna FAQ
Which is cheaper, GLM-5.3-Flash or GPT-5.6 Luna?
GLM-5.3-Flash is 25% cheaper per 1M input tokens than GPT-5.6 Luna, $0.15 vs $0.20. For 10M input and 2M output tokens, GLM-5.3-Flash costs $2.50 and GPT-5.6 Luna $4.40 at standard rates.
Which scores higher on independent benchmarks, GLM-5.3-Flash or GPT-5.6 Luna?
GLM-5.3-Flash leads on Arena Text, 1475 Elo to 1452 Elo; GPT-5.6 Luna leads on GPQA Diamond, 91.6% to 90.2%; GPT-5.6 Luna leads on FrontierMath Tiers 1-3 (v2), 82.1% to 55.8%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, GLM-5.3-Flash or GPT-5.6 Luna?
GPT-5.6 Luna has the larger context window, 1,050,000 vs 1,000,000 tokens.
Can I run GLM-5.3-Flash or GPT-5.6 Luna myself?
GLM-5.3-Flash is released as open weights you can run yourself; GPT-5.6 Luna is available through its provider's API only.
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Production evaluation
Choosing between GLM-5.3-Flash and GPT-5.6 Luna?
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