Model comparison
Claude Mythos 5.1 vs Grok 4.20 Reasoning
Compare Claude Mythos 5.1 vs Grok 4.20 Reasoning API pricing: input/output token costs, cache pricing, context windows, workload estimates, and routing fit.
Claude Mythos 5.1
anthropic · claude-mythos-5-1
- Input
- $10
- Output
- $50
- Context
- 1M
Grok 4.20 Reasoning
xai · grok-4.20-0309-reasoning
- Input
- $1.25
- Output
- $2.5
- Context
- 1M
Quick take
Grok 4.20 Reasoning has the lower input price at $1.25 per 1M input tokens. Grok 4.20 Reasoning is cheaper for the example blended workload below. Claude Mythos 5.1 has the larger context window at 1M tokens.
Choose Claude Mythos 5.1 if...
- Claude Mythos 5.1 gives more room for long generated answers, reports, or code output.
Choose Grok 4.20 Reasoning if...
- Grok 4.20 Reasoning is the better default for cost-sensitive traffic and repeated high-volume calls.
Example workload cost
Estimates use input tokens plus 20% output tokens. They exclude provider discounts, cache hits, and tool/search surcharges.
| Workload | Claude Mythos 5.1 | Grok 4.20 Reasoning | Cheaper |
|---|---|---|---|
| 1M input + 200K output | $20.00 | $1.75 | Grok 4.20 Reasoning |
| 10M input + 2M output | $200.00 | $17.50 | Grok 4.20 Reasoning |
| 100M input + 20M output | $2,000.00 | $175.00 | Grok 4.20 Reasoning |
Context, output, and capability fit
Claude Mythos 5.1 provides the larger context window. Check max output separately when the task needs long reports, code generation, or full-document rewrites.
- Claude Mythos 5.1 max output
- 128K
- Grok 4.20 Reasoning max output
- n/a
- Claude Mythos 5.1 features
- prompt caching, function calling, vision
- Grok 4.20 Reasoning features
- prompt caching, function calling, vision
Risk notes for Claude Mythos 5.1
- High output price: cap max tokens for verbose generation workloads.
Risk notes for Grok 4.20 Reasoning
- No major capability risk is flagged in this snapshot, but provider pages should still be verified before production routing.
Routing tags
frontierpremiumreasoningcodingagentslong-contextmultimodalcache-friendlymythos-classlimited-availabilityrag