GPT-6 Astra vs Claude Mythos 5.1
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by OpenAI
|
by Anthropic
|
|---|---|---|
| Overview | ||
| Status | Current flagship | Current flagship |
| Released | ||
| Pricing per million tokens | ||
| Input | $10.00/Mtok | $10.00/Mtok |
| Output | $50.00/Mtok | $50.00/Mtok |
| Blended avg | $20.00/Mtok | $20.00/Mtok |
| Cached input | $1.00/Mtok | $0.250/Mtok |
| Price basis | OpenAI's rate card prices this model by context length: the tracked figure is the short-context tier, and prompts over 272K input tokens bill at the long-context tier of $20 input / $2 cached input / $25 cache write / $75 output per 1M tokens — 2x input and cache rates and 1.5x output, applied to the full request. Cache writes bill at 1.25x the uncached input rate. Batch and Flex are 50% of Standard; Fast mode is 2x the applicable rate, and Fast is unavailable with EU data residency. | Cache hits and refreshes on Claude Mythos 5.1 (and Claude Fable 5.1) are priced at 0.025x the base input price — $0.25 per 1M tokens — where every other Claude model uses the standard 0.1x multiplier. Base $10/$50 per 1M tokens; Batch API $5/$25. Verified 2026-09-01 against platform.claude.com/docs/en/about-claude/pricing. |
| Specifications | ||
| Context window | 1M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimage
|
| Benchmarks source: Vellum LLM Leaderboard | ||
| Avg benchmark score | 96 | 55.9 |
| Perf / dollar | 4.8 | 2.8 |
| AutoBench | 41.4 | 31.4 |
| GPQA Diamond | 96 | — |
| Terminal-Bench 2.1 | — | 60.9 |
| OSWorld-Verified | — | 41.7 |
| Humanity's Last Exam | — | 65 |
| Independent composite scores each on its own scale — not part of the average above | ||
| AA Intelligence Index | 61.2 | — |
| AA Agentic Index | 51.5 | — |
| AA-Omniscience Index (−100–100) | 43.4 | — |
| GDPval-AA v2 | 1629.3 ELO | — |
| Providers | ||
| Available from |
OpenAI — $10.00/$50.00/Mtok
|
Anthropic — $10.00/$50.00/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | GPT-6 Astra | Claude Mythos 5.1 | Savings |
|---|---|---|---|
| 1M tokens | $20 | $20 | $0 (0%) |
| 10M tokens | $200 | $200 | $0 (0%) |
| 100M tokens | $2000 | $2000 | $0 (0%) |
| 1000M tokens | $20000 | $20000 | $0 (0%) |
When to pick which
distilled from the pricing and spec data above- raw capability matters more than price: 96 vs 55.9 average benchmark score
- your workload re-reads context (agents, RAG, long chats): cached input costs $0.250/Mtok — 98% off its list input price
The cheaper option here — GPT-6 Astra costs $20.00/Mtok blended on OpenAI.
Summary
GPT-6 Astra by OpenAI costs $10.00/Mtok input and $50.00/Mtok output, with a 1M-token context window. It supports text, image input.
Claude Mythos 5.1 by Anthropic costs $10.00/Mtok input and $50.00/Mtok output, with a 1M-token context window. It supports text, image input.
On benchmarks, GPT-6 Astra scores higher (96 vs 55.9) on average. In terms of value, GPT-6 Astra has better performance per dollar (4.8 vs 2.8).
Note: Pricing is per million tokens. Actual costs vary with usage patterns, prompt caching, and batch discounts. Always verify against official provider pricing pages.