Claude Mythos 5.1 vs GPT-5.6 Sol
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
GPT-5.6 Sol is 60% cheaper on blended cost ($8.00 vs $20.00/Mtok)
| Specification |
by Anthropic
|
GPT-5.6 SolIntro price
by OpenAI
|
|---|---|---|
| Overview | ||
| Status | Current flagship | Current flagship |
| Released | Sep 1, 2026 | Jul 9, 2026 |
| Pricing per million tokens | ||
| Input | $10.00/Mtok | $4.00/Mtok |
| Output | $50.00/Mtok | $20.00/Mtok |
| Blended avg | $20.00/Mtok | $8.00/Mtok |
| Cached input | $0.250/Mtok | $0.400/Mtok |
| Price basis | 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. | OpenAI labels this promotional pricing and states it is "available at least through November 21, 2026". That is a floor, not a reversion date — OpenAI publishes no date on which the rate goes back up, so no reversion is claimed here and no countdown is implied. Until 2026-08-21 this model billed $5 input / $0.50 cached input / $30 output per 1M tokens. OpenAI's rate card also prices this model by context length: the tracked figure is the short-context tier, and prompts over the short-context threshold bill at the long-context tier of $8 input / $0.80 cached input / $10 cache write / $30 output per 1M tokens. Cache writes bill at 1.25x the uncached input rate. |
| Specifications | ||
| Context window | 1M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimage
|
| Benchmarks source: Vellum LLM Leaderboard | ||
| Avg benchmark score | 55.9 | 83.8 |
| Perf / dollar | 2.8 | 10.5 |
| Terminal-Bench 2.1 | 60.9 | 88.8 |
| OSWorld-Verified | 41.7 | 62.6 |
| Humanity's Last Exam | 65 | 47.2 |
| AutoBench | 31.4 | 18.1 |
| GPQA Diamond | — | 94.6 |
| SWE-Bench Verified | — | 96.2 |
| BrowseComp | — | 92.2 |
| ARC-AGI 2 | — | 92.5 |
| HumanEval | — | 96.2 |
| Independent composite scores each on its own scale — not part of the average above | ||
| AA Intelligence Index | — | 60.9 |
| AA Agentic Index | — | 57.8 |
| AA-Omniscience Index (−100–100) | — | 22 |
| GDPval-AA v2 | — | 1710.1 ELO |
| LMSYS Chatbot Arena | — | 1482.2 ELO |
| Providers | ||
| Available from |
Anthropic — $10.00/$50.00/Mtok
|
OpenAI — $4.00/$20.00/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Claude Mythos 5.1 | GPT-5.6 Sol | Savings |
|---|---|---|---|
| 1M tokens | $20 | $8 | $12 (60%) |
| 10M tokens | $200 | $80 | $120 (60%) |
| 100M tokens | $2000 | $800 | $1200 (60%) |
| 1000M tokens | $20000 | $8000 | $12000 (60%) |
When to pick which
distilled from the pricing and spec data above
Pick Claude Mythos 5.1 if…
- your workload re-reads context (agents, RAG, long chats): cached input costs $0.250/Mtok — 98% off its list input price
Pick GPT-5.6 Sol if…
- cost dominates: $8.00/Mtok blended vs $20.00 — 60% less on the same 50/50 token mix
- raw capability matters more than price: 83.8 vs 55.9 average benchmark score
Price movement
recorded changes since we began tracking each model · last checked Sep 1, 2026| Model | Changes | Latest move | Old → new $/M |
|---|---|---|---|
| Claude Mythos 5.1 | 0 | — no move | Stable since we began tracking — no change recorded |
| GPT-5.6 Sol | 1 | price cut on Aug 21, 2026 | $5/$30 → $4/$20/Mtok |
Only GPT-5.6 Sol has changed price since we began tracking; Claude Mythos 5.1 has held steady.
See all recent price moves →
MODELPRICEWATCH.COM · 2026-09-01
Try GPT-5.6 Sol on OpenAI
The cheaper option here — GPT-5.6 Sol costs $8.00/Mtok blended on OpenAI.
Summary
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.
GPT-5.6 Sol by OpenAI costs $4.00/Mtok input and $20.00/Mtok output, with a 1M-token context window. It supports text, image input.
On a blended cost basis, GPT-5.6 Sol is 60% cheaper than Claude Mythos 5.1.It also has a larger context window.
On benchmarks, GPT-5.6 Sol scores higher (83.8 vs 55.9) on average. In terms of value, GPT-5.6 Sol has better performance per dollar (10.5 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.
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