AI model comparison
Claude Sonnet 5.5 vs GLM 5.3 Flash
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Anthropic
Claude Sonnet 5.5
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade.
- Input / 1M
- $2
- Output / 1M
- $10
- Context
- 1M
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
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
GLM 5.3 Flash
16.4x cheaper for a typical chat
Higher intelligence score
Claude Sonnet 5.5
56 vs 41.8 on Artificial Analysis
Larger context window
GLM 5.3 Flash
1.05M vs 1M tokens
Newer release
Claude Sonnet 5.5
Released September 28, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Sonnet 5.556Coding index
Claude Sonnet 5.5Not availableAgentic index
Claude Sonnet 5.5Not availablePricing
Claude Sonnet 5.5 vs GLM 5.3 Flash API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Sonnet 5.5 | |
|---|---|---|
| Input tokensPer 1M tokens | $2 | $0.15 |
| Output tokensPer 1M tokens | $10 | $0.50 |
| Cached input (read)Per 1M tokens | $0.10 | $0.03 |
| Cache writePer 1M tokens | $2.50 | Not available |
| Web searchPer request | $0.01 | Not available |
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
Claude Sonnet 5.5$9Coding task
30K in, 4K out
Claude Sonnet 5.5$100$43 cachedLong document summary
150K in, 2K out
Claude Sonnet 5.5$320$35 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Sonnet 5.5 | |
|---|---|---|
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 944K tokens |
| Input types | File, Image, Text | Image, Text, Video |
| Output types | Text | Text |
| Reasoning effort levels | Max, Extra high, High, Medium, Low | Max, High, Low |
| Default reasoning effort | High | Max |
| Release date | September 28, 2026 | August 26, 2026 |
Features
Supported features
API features available for each model.
| Metric | Claude Sonnet 5.5 | |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Not supported | Supported |
| Verbosity control | Supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Claude Sonnet 5.5View full model details- Claude Sonnet 5.5 vs Claude Opus 5.5
- Claude Sonnet 5.5 vs Claude Fable 5.1
- Claude Sonnet 5.5 vs GPT-6 Astra
- Claude Sonnet 5.5 vs GPT-6.1 Sol
- Claude Sonnet 5.5 vs Claude Opus 5
- Claude Sonnet 5.5 vs Claude Fable 5
- Claude Sonnet 5.5 vs Muse Spark 1.3
- Claude Sonnet 5.5 vs GPT-6 Sol
- Claude Sonnet 5.5 vs GPT-5.6 Sol
- Claude Sonnet 5.5 vs Grok 4.7
- Claude Sonnet 5.5 vs GLM 5.3
- Claude Sonnet 5.5 vs DeepSeek V4.1 Flash
- Claude Sonnet 5.5 vs MiMo-V2.6-Flash
- Claude Sonnet 5.5 vs Hy4 preview
- Claude Sonnet 5.5 vs GPT-6 Luna
- Claude Sonnet 5.5 vs DeepSeek V4 Flash 0731
- 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 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
- GLM 5.3 Flash vs GPT-5.6 Luna Pro
Our take
GLM 5.3 Flash is 16.4x cheaper for a typical chat. Claude Sonnet 5.5 scores higher on the Artificial Analysis Intelligence Index (56 vs 41.8). GLM 5.3 Flash has the larger context window (1.05M vs 1M 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 Claude Sonnet 5.5 or GLM 5.3 Flash 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 Claude Sonnet 5.5 costs $2 per 1M input tokens and $10 per 1M output tokens.
Which has a bigger context window, Claude Sonnet 5.5 or GLM 5.3 Flash?
GLM 5.3 Flash supports up to 1.05M tokens of context, compared with 1M for Claude Sonnet 5.5.
Is Claude Sonnet 5.5 smarter than GLM 5.3 Flash?
On the Artificial Analysis Intelligence Index, Claude Sonnet 5.5 scores 56 and GLM 5.3 Flash scores 41.8, putting Claude Sonnet 5.5 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Claude Sonnet 5.5 and GLM 5.3 Flash at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Claude Sonnet 5.5 and GLM 5.3 Flash answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Claude Sonnet 5.5 and GLM 5.3 Flash at the same time. Compare the answers side by side and keep the best one.