Skip to main content
idapt
HomeAI ModelsPricing
Sign inStart free

Claude Fable 5 vs Grok 4.20

At a glance
AnthropicClaude Fable 5

Anthropic's Mythos-class flagship for ambitious, long-running professional work.

921M ctx$10.00/$50.00 per M#2/92
xAIGrok 4.20

xAI's newest flagship model with industry-leading speed and agentic tool calling.

862M ctx$1.25/$2.50 per M#12/92
AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
AnthropicClaude Fable 5
Reasoning
CodingInsufficient data
AgenticInsufficient data
ReasoningInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Smarter
Capability
CapabilityECI91.6
Reasoning & Knowledge
Factual Recall68.3%
Math
Competition Math99.7%
Agentic
Terminal Tasks—Novel Reasoning—
xAIGrok 4.20
Reasoning
CodingInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Cheaper
Capability
CapabilityECI85.7
Reasoning & Knowledge
Factual Recall—
Math
Competition Math—
Agentic
Terminal Tasks57.3%Novel Reasoning65.1%
Specs
AnthropicClaude Fable 5
1M
Context
128K
Max output
Jun 2026
Released
xAIGrok 4.20
2M
Context
16K
Max output
Mar 2026
Released
Capabilities
AnthropicClaude Fable 5
Vision
Audio
Reasoning
xAIGrok 4.20
Vision
Audio
Reasoning
Pricing
AnthropicClaude Fable 5
Live pricing, shown before you run
Input$10.00/M tokens
Output$50.00/M tokens
Cache read$1.00/M tokens
Cache write$12.50/M tokens
Web search$0.01/search
xAIGrok 4.20
Live pricing, shown before you run
Input$1.25/M tokens
Output$2.50/M tokens
Cache read$0.20/M tokens
Web search$0.005/search
Chat with Claude Fable 5Go to model
Chat with Grok 4.20Go to model
Frequently Asked Questions: Claude Fable 5 vs Grok 4.20▼

Which is better, Claude Fable 5 or Grok 4.20?

▼

Based on the Capability Index, Claude Fable 5 scores higher (91.6 vs 85.7). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.

Which is cheaper, Claude Fable 5 or Grok 4.20?

▼

Grok 4.20 has a lower blended cost. Claude Fable 5: $10.00 input / $50.00 output. Grok 4.20: $1.25 input / $2.50 output.

Which has a larger context window, Claude Fable 5 or Grok 4.20?

▼

Grok 4.20 has a larger context window: Claude Fable 5 supports 1M tokens vs Grok 4.20 at 2M tokens.

Do both Claude Fable 5 and Grok 4.20 support vision?

▼

Yes, both Claude Fable 5 and Grok 4.20 support vision/image input.

What are the key differences between Claude Fable 5 and Grok 4.20?

▼

Key differences: Claude Fable 5 has a notably higher capability index (5.9 point gap); Grok 4.20 is significantly cheaper. 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 and Grok 4.20 for free on idapt.app to see which performs better for your specific needs.

Open in App
  • Home
  • Pricing
  • AI Models
  • Image models
  • Voice models
  • Video models
  • Rankings
  • New models
  • Model status
  • Multi-Model Chat
  • Voice Mode
  • Voice HUD
  • Web Search
  • Image Generation
  • Video Generation
  • Audio Generation
  • Transcription
  • Drive
  • Secrets
  • Sharing
  • Workspaces
  • Tasks
  • Memory
  • Agents
  • Subagents
  • Automations
  • Skills
  • Code Execution
  • Computers
  • Computer Use
  • Cloud Computers
  • Local AI
  • AI Gateway
  • API & SDK
  • CLI
  • MCP
  • Tunnels
  • All features →
  • Blog
  • Use cases
  • Comparisons
  • Best of
  • Learn
  • Free tools
  • Prompts
  • Templates
  • Changelog
  • Help center
  • FAQ
  • Privacy
  • Compare all models
  • Support
  • Developers
  • Quickstarts
  • API reference
  • API pricing
  • CLI
  • MCP
  • Downloads
  • Desktop
  • Badges and embeds
© idapt[email protected]TermsPrivacy PolicyLegal noticeReport content
X (Twitter)