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Claude Fable 5.1 vs Mercury 2.5

At a glance

Anthropic's upgraded Mythos-class flagship, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work.

1M ctx$10.00/$50.00 per M

Inception's latest diffusion LLM and the fastest reasoning model available, producing and refining tokens in parallel instead of one at a time.

260K ctx$0.04/$0.15 per M
Demos
All demos

No shared demos for these models yet.

AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
Reasoning
CodingInsufficient data
AgenticInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:OpenRouter
Reasoning
CodingInsufficient data
AgenticInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:OpenRouter
Cheaper100%
Specs
1M
Context
128K
Max output
Sep 2026
Released
260K
Context
66K
Max output
Sep 2026
Released
Capabilities
Vision
Audio
Reasoning
Vision
Audio
Reasoning
Pricing
Live pricing, shown before you run
Input$10.00/M tokens
Output$50.00/M tokens
Cache read$0.25/M tokens
Cache write$12.50/M tokens
Web search$0.01/search
Live pricing, shown before you run
Input100%$0.04/M tokens
Output100%$0.15/M tokens
Cache read98%$0.004/M tokens
Chat with Claude Fable 5.1Go to model
Chat with Mercury 2.5Go to model
Frequently Asked Questions: Claude Fable 5.1 vs Mercury 2.5▼

Which is better, Claude Fable 5.1 or Mercury 2.5?

▼

Both Claude Fable 5.1 and Mercury 2.5 are capable AI models. The best choice depends on your specific use case: consider pricing, context window, speed, and which capabilities (vision, reasoning, audio) you need.

Which is cheaper, Claude Fable 5.1 or Mercury 2.5?

▼

Mercury 2.5 has a lower blended cost. Claude Fable 5.1: $10.00 input / $50.00 output. Mercury 2.5: $0.04 input / $0.15 output.

Which has a larger context window, Claude Fable 5.1 or Mercury 2.5?

▼

Claude Fable 5.1 has a larger context window: Claude Fable 5.1 supports 1M tokens vs Mercury 2.5 at 260K tokens.

Do both Claude Fable 5.1 and Mercury 2.5 support vision?

▼

Claude Fable 5.1 supports vision/image input, but Mercury 2.5 does not.

What are the key differences between Claude Fable 5.1 and Mercury 2.5?

▼

Key differences: Mercury 2.5 is significantly cheaper; only Claude Fable 5.1 supports vision input. Compare full specs on this page.

Which model should I choose for my use case?

▼

If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Claude Fable 5.1 and Mercury 2.5 for free on idapt.app to see which performs better for your specific needs.

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