Model comparison - Same provider, successor
Claude Mythos 5 vs Claude Mythos 5.1
Claude Mythos 5 and Claude Mythos 5.1 are both Anthropic models. Both list the same first-party API price: $10 per 1M input tokens and $50 per 1M output tokens. Claude Mythos 5 and Claude Mythos 5.1 both have a 1,000,000-token context window, and both return up to 128,000 output tokens per response. Claude Mythos 5 was released on June 9, 2026 and Claude Mythos 5.1 on September 1, 2026. Both are closed-weights models, available only through an API.
Last verified from each provider's pricing page. All sources
Side-by-side specs
| Spec | Claude Mythos 5 | Claude Mythos 5.1 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Input / 1M tokens | $10 | $10 |
| Output / 1M tokens | $50 | $50 |
| Cache read / 1M | $1 | $0.25 |
| Cache write / 1M | $12.50 | $12.50 |
| Batch input / 1M | $5 | $5 |
| Batch output / 1M | $25 | $25 |
| Context window | 1,000,000 | 1,000,000 |
| Max output | 128,000 | 128,000 |
| Release date | ||
| Weights | Closed | Closed |
| API model id | claude-mythos-5 | claude-mythos-5-1 |
| Last verified |
Prices in USD per 1M tokens at each provider's standard first-party rate. A dash means the provider does not bill that item separately or no primary page states it.
What each costs in practice
The same three workloads every model page uses, worked from each model's standard list rates. Swap in your own token counts with the math on each model's page.
| Workload | Claude Mythos 5 | Claude Mythos 5.1 |
|---|---|---|
| One agent session1M input tokens and 100K output tokens, no caching. | $15.00 | $15.00 |
| A chat app10,000 requests a day at 2K input and 500 output tokens each. | $450.00$13,500.00 per 30-day month | $450.00$13,500.00 per 30-day month |
| The same session at a 90% cache hit90% of the input is read from the prompt cache. The one-time cache write premium is not included. | $6.90 | $6.23 |
Show the math
Claude Mythos 5
- One agent sessionInput: 1M x $10 = $10.00Output: 0.1M x $50 = $5.00
- A chat appInput: 20M x $10 = $200.00Output: 5M x $50 = $250.00
- The same session at a 90% cache hitCached input: 0.9M x $1 = $0.90Uncached input: 0.1M x $10 = $1.00Output: 0.1M x $50 = $5.00
Claude Mythos 5.1
- One agent sessionInput: 1M x $10 = $10.00Output: 0.1M x $50 = $5.00
- A chat appInput: 20M x $10 = $200.00Output: 5M x $50 = $250.00
- The same session at a 90% cache hitCached input: 0.9M x $0.25 = $0.225Uncached input: 0.1M x $10 = $1.00Output: 0.1M x $50 = $5.00
Benchmarks under the same setting
No board in the benchmark directory lists both Claude Mythos 5 and Claude Mythos 5.1 under the same setting, so there is no like-for-like score to show here.
Model pages
FAQ
How do Claude Mythos 5 and Claude Mythos 5.1 compare on price?
Both list the same first-party API price: $10 per 1M input tokens and $50 per 1M output tokens. For one agent session of 1M input and 100K output tokens with no caching, that is $15.00 on Claude Mythos 5 and $15.00 on Claude Mythos 5.1. Prices are each provider's first-party list rates, verified October 17, 2026 and October 17, 2026.
What are the context windows of Claude Mythos 5 and Claude Mythos 5.1?
Claude Mythos 5 and Claude Mythos 5.1 both have a 1,000,000-token context window, and both return up to 128,000 output tokens per response.
Are Claude Mythos 5 and Claude Mythos 5.1 open weights?
Claude Mythos 5 is closed-weights and is called through Anthropic's API as claude-mythos-5. Claude Mythos 5.1 is closed-weights and is called through Anthropic's API as claude-mythos-5-1.
Sources
Claude Mythos 5 verified from platform.claude.com; Claude Mythos 5.1 verified from platform.claude.com. This page is as current as the older of the two: .
- https://platform.claude.com/docs/en/about-claude/pricing
- https://platform.claude.com/docs/en/models/mythos-5/overview
- https://platform.claude.com/docs/en/about-claude/models/overview
- https://platform.claude.com/docs/en/release-notes/overview
- https://platform.claude.com/docs/en/about-claude/model-deprecations
- https://platform.claude.com/docs/en/models/mythos-5-1/overview
Newsletter
Get model price changes as they ship
One email per week. New model releases, price cuts and what they mean for your bill.