AI model comparison
GLM 5.3 Flash vs GPT-5.6 Luna Pro
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Z.ai
GLM 5.3 Flash
GLM-5.3-Flash is a native multimodal model from Z.ai. It is suited for efficient coding and long-horizon agent tasks.
- Input / 1M
- $0.15
- Output / 1M
- $0.50
- Context
- 1.05M
OpenAI
GPT-5.6 Luna Pro
GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks.
- Input / 1M
- $0.20
- Output / 1M
- $1.20
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
GLM 5.3 Flash
1.8x cheaper for a typical chat
Higher intelligence score
Tie
Not enough benchmark data
Larger context window
GPT-5.6 Luna Pro
1.05M vs 1.05M tokens
Newer release
GLM 5.3 Flash
Released August 26, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
GPT-5.6 Luna ProNot availableCoding index
GPT-5.6 Luna ProNot availableAgentic index
GPT-5.6 Luna ProNot availablePricing
GLM 5.3 Flash vs GPT-5.6 Luna Pro API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | GPT-5.6 Luna Pro | |
|---|---|---|
| Input tokensPer 1M tokens | $0.15 | $0.20 |
| Output tokensPer 1M tokens | $0.50 | $1.20 |
| Cached input (read)Per 1M tokens | $0.03 | $0.02 |
| Cache writePer 1M tokens | Not available | $0.25 |
| Long-context pricingPer 1M tokens, for very long prompts | Same rate at any length | $0.40 in / $1.80 out above 272K |
| Web searchPer request | Not available | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
GPT-5.6 Luna Pro$1Coding task
30K in, 4K out
GPT-5.6 Luna Pro$10.80$5.40 cachedLong document summary
150K in, 2K out
GPT-5.6 Luna Pro$32.40$5.40 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | GPT-5.6 Luna Pro | |
|---|---|---|
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 944K tokens | 128K tokens |
| Input types | Image, Text, Video | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | Max, High, Low | Max, Extra high, High, Medium, Low, None |
| Default reasoning effort | Max | Medium |
| Release date | August 26, 2026 | July 9, 2026 |
Features
Supported features
API features available for each model.
| Metric | GPT-5.6 Luna Pro | |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Not supported |
| Stop sequences | Supported | Not supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Not supported | Supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
- GLM 5.3 Flash vs DeepSeek V4.1 Flash
- GLM 5.3 Flash vs MiMo-V2.6-Flash
- GLM 5.3 Flash vs Hy4 preview
- GLM 5.3 Flash vs GPT-6 Luna
- GLM 5.3 Flash vs DeepSeek V4 Flash 0731
- GLM 5.3 Flash vs Claude Opus 5.5
- GLM 5.3 Flash vs GLM 5.3
- GLM 5.3 Flash vs DeepSeek V4 Flash 0423
- GLM 5.3 Flash vs Step 5 Preview
- GLM 5.3 Flash vs Gemini 3.8 Flash
- GLM 5.3 Flash vs Hy3
- GLM 5.3 Flash vs GPT-5.6 Luna
- GLM 5.3 Flash vs GPT-6.1 Sol
- GLM 5.3 Flash vs Muse Spark 1.3 Contributor
- GLM 5.3 Flash vs Claude Sonnet 5.5
- GLM 5.3 Flash vs Claude Fable 5.1
- GLM 5.3 Flash vs GPT-6 Astra
- GLM 5.3 Flash vs MiMo-V2.6-Pro
- GLM 5.3 Flash vs Claude Opus 5
- GLM 5.3 Flash vs DeepSeek V4 Pro 0813
- GLM 5.3 Flash vs Claude Haiku 5.5
- GLM 5.3 Flash vs Ling 3.1 Flash
- GLM 5.3 Flash vs GPT-6 Luna Pro
- GLM 5.3 Flash vs Gemini 3.7 Flash
- GLM 5.3 Flash vs Muse Spark 1.2
- GLM 5.3 Flash vs Qwen3.8 Flash
- GLM 5.3 Flash vs Qwen3.7 Flash
- GLM 5.3 Flash vs DeepSeek V4 Flash Vision Exp
- GLM 5.3 Flash vs Mistral Nemo
- GLM 5.3 Flash vs GLM 5.3 FlashX
GPT-5.6 Luna ProView full model details- GPT-5.6 Luna Pro vs DeepSeek V4.1 Flash
- GPT-5.6 Luna Pro vs Hy4 preview
- GPT-5.6 Luna Pro vs GPT-6 Luna
- GPT-5.6 Luna Pro vs DeepSeek V4 Flash 0731
- GPT-5.6 Luna Pro vs DeepSeek V4 Flash 0423
- GPT-5.6 Luna Pro vs GPT-5.6 Luna
- GPT-5.6 Luna Pro vs MiniMax M3
- GPT-5.6 Luna Pro vs GPT-5.4 Nano
- GPT-5.6 Luna Pro vs GPT-4.1 Mini
Our take
GLM 5.3 Flash is 1.8x cheaper for a typical chat. GPT-5.6 Luna Pro has the larger context window (1.05M vs 1.05M tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is GLM 5.3 Flash or GPT-5.6 Luna Pro cheaper?
GLM 5.3 Flash is cheaper for a typical chat (2K input tokens and 500 output tokens). GLM 5.3 Flash costs $0.15 per 1M input tokens and $0.50 per 1M output tokens, while GPT-5.6 Luna Pro costs $0.20 per 1M input tokens and $1.20 per 1M output tokens.
Which has a bigger context window, GLM 5.3 Flash or GPT-5.6 Luna Pro?
GPT-5.6 Luna Pro supports up to 1.05M tokens of context, compared with 1.05M for GLM 5.3 Flash.
Can I use GLM 5.3 Flash and GPT-5.6 Luna Pro at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see GLM 5.3 Flash and GPT-5.6 Luna Pro answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to GLM 5.3 Flash and GPT-5.6 Luna Pro at the same time. Compare the answers side by side and keep the best one.