AI model comparison
Step 5 Preview vs Claude Fable 5.1
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
StepFun
Step 5 Preview
Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters).
- Input / 1M
- $1
- Output / 1M
- $2.70
- Context
- 1M
Anthropic
Claude Fable 5.1
Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual
- Input / 1M
- $10
- Output / 1M
- $50
- Context
- 1M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Step 5 Preview
13.4x cheaper for a typical chat
Higher intelligence score
Tie
Not enough benchmark data
Larger context window
Tie
1M vs 1M tokens
Newer release
Step 5 Preview
Released October 8, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Fable 5.153.4Coding index
Claude Fable 5.181.6Agentic index
Claude Fable 5.157.9Pricing
Step 5 Preview vs Claude Fable 5.1 API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Fable 5.1 | |
|---|---|---|
| Input tokensPer 1M tokens | $1 | $10 |
| Output tokensPer 1M tokens | $2.70 | $50 |
| Cached input (read)Per 1M tokens | $0.05 | $0.25 |
| Cache writePer 1M tokens | Not available | $12.50 |
| 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
Claude Fable 5.1$45Coding task
30K in, 4K out
Claude Fable 5.1$500$207.50 cachedLong document summary
150K in, 2K out
Claude Fable 5.1$1600$137.50 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Fable 5.1 | |
|---|---|---|
| Context window | 1M tokens | 1M tokens |
| Max output | 64K tokens | 128K tokens |
| Input types | Image, Text, Video | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low | Max, Extra high, High, Medium, Low |
| Default reasoning effort | Medium | High |
| Release date | October 8, 2026 | September 1, 2026 |
Features
Supported features
API features available for each model.
| Metric | Claude Fable 5.1 | |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Not supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Not supported | Not 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.
- Step 5 Preview vs DeepSeek V4.1 Flash
- Step 5 Preview vs GLM 5.3 Flash
- Step 5 Preview vs MiMo-V2.6-Flash
- Step 5 Preview vs Hy4 preview
- Step 5 Preview vs GPT-6 Luna
- Step 5 Preview vs DeepSeek V4 Flash 0731
- Step 5 Preview vs Claude Opus 5.5
- Step 5 Preview vs GLM 5.3
- Step 5 Preview vs DeepSeek V4 Flash 0423
- Step 5 Preview vs Hy3
- Step 5 Preview vs Claude Sonnet 5.5
- Step 5 Preview vs Gemini 3.8 Flash
- Step 5 Preview vs GPT-6.1 Sol
- Step 5 Preview vs DeepSeek V4 Pro 0813
- Step 5 Preview vs Gemini 3 Flash Preview
- Step 5 Preview vs Claude Opus 5
- Step 5 Preview vs GPT-6 Astra
- Step 5 Preview vs Qwen3.8 27B
- Step 5 Preview vs Gemini 2.5 Flash
- Step 5 Preview vs GLM 5.3 FlashX
- Step 5 Preview vs GPT-5.6 Luna Pro
Claude Fable 5.1View full model details- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Fable 5.1 vs Claude Sonnet 5.5
- Claude Fable 5.1 vs GPT-6 Astra
- Claude Fable 5.1 vs GPT-6.1 Sol
- Claude Fable 5.1 vs Claude Opus 5
- Claude Fable 5.1 vs Claude Fable 5
- Claude Fable 5.1 vs Muse Spark 1.3
- Claude Fable 5.1 vs GPT-6 Sol
- Claude Fable 5.1 vs GPT-5.6 Sol
- Claude Fable 5.1 vs Kimi K3
- Claude Fable 5.1 vs GLM 5.3 Flash
- Claude Fable 5.1 vs Claude Opus 4.8
- Claude Fable 5.1 vs DeepSeek V4.1 Flash
- Claude Fable 5.1 vs GPT-6 Luna
- Claude Fable 5.1 vs MiMo-V2.6-Flash
- Claude Fable 5.1 vs Hy4 preview
Our take
Step 5 Preview is 13.4x cheaper for a typical chat. 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 Step 5 Preview or Claude Fable 5.1 cheaper?
Step 5 Preview is cheaper for a typical chat (2K input tokens and 500 output tokens). Step 5 Preview costs $1 per 1M input tokens and $2.70 per 1M output tokens, while Claude Fable 5.1 costs $10 per 1M input tokens and $50 per 1M output tokens.
Which has a bigger context window, Step 5 Preview or Claude Fable 5.1?
Step 5 Preview supports up to 1M tokens of context, compared with 1M for Claude Fable 5.1.
Can I use Step 5 Preview and Claude Fable 5.1 at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Step 5 Preview and Claude Fable 5.1 answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Step 5 Preview and Claude Fable 5.1 at the same time. Compare the answers side by side and keep the best one.