High-volume, cost-sensitive work
Choose Claude Mythos 5.1
Claude Mythos 5.1 costs 47% less on a typical mix of three input tokens for every output token ($20.00 against $37.50 per million tokens).
Claude Mythos 5.1 vs GPT-4: price, context and capabilities
Choose Claude Mythos 5.1 for high-volume, cost-sensitive work, writing and code generation, very long inputs, images as input and the latest release; on the other points the two are level or the data is missing.
In short
- Claude Mythos 5.1 is 47% cheaper than GPT-4 at the headline price ($20.00 / 1M tokens vs $37.50 / 1M tokens).
- Claude Mythos 5.1 reads more per request: 1M tokens against 8k.
- Claude Mythos 5.1 is the newer model (September 2026, against March 2023).
- Only Claude Mythos 5.1 offers vision, reasoning, prompt caching.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Claude Mythos 5.1
Claude Mythos 5.1 charges $50.00 per million output tokens, against $60.00 for GPT-4. Output dominates the bill when answers are long.
Very long inputs
Choose Claude Mythos 5.1
Claude Mythos 5.1 reads up to 1M tokens per request, against 8k for GPT-4.
Images as input
Choose Claude Mythos 5.1
Claude Mythos 5.1 accepts images as input; GPT-4 does not.
Latest release
Choose Claude Mythos 5.1
Claude Mythos 5.1 is the newer release (September 2026, against March 2023 for GPT-4).
Monthly cost at three volumes
| Volume | Claude Mythos 5.1 | GPT-4 | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $22.50 | $45.00 | Claude Mythos 5.1, $22.50 less |
| Production: 20M input, 5M output tokens | $450.00 | $900.00 | Claude Mythos 5.1, $450.00 less |
| Scale: 500M input, 100M output tokens | $10,000 | $21,000 | Claude Mythos 5.1, $11,000 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Mythos 5.1 | GPT-4 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available · Limited access | Deprecated |
| Headline price | $20.00 / 1M tokens | $37.50 / 1M tokens |
| Input | $10.00 / 1M tokens | $30.00 / 1M tokens |
| Output | $50.00 / 1M tokens | $60.00 / 1M tokens |
| Cached input | $0.25 / 1M tokens | No data |
| Context window | 1M | 8k |
| Max output | 128k | 8k |
| Released | September 2026 | March 2023 |
| Knowledge cutoff | No data | December 2023 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Tool calling, Structured output, Batch API |
| API model id | claude-mythos-5-1 | gpt-4 |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Mythos 5.1 | GPT-4 |
|---|---|---|
| GPQA Diamond | No data | 34.9% |
| IFBench (instruction following) | No data | 33.2% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Mythos 5.1 or GPT-4?
Choose Claude Mythos 5.1 for high-volume, cost-sensitive work, writing and code generation, very long inputs, images as input and the latest release; on the other points the two are level or the data is missing.
Which is cheaper, Claude Mythos 5.1 or GPT-4?
Claude Mythos 5.1 is 47% cheaper than GPT-4 at the headline price ($20.00 / 1M tokens vs $37.50 / 1M tokens).
Which has the larger context window, Claude Mythos 5.1 or GPT-4?
Claude Mythos 5.1 reads more per request: 1M tokens against 8k.
What is the difference between Claude Mythos 5.1 and GPT-4?
Claude Mythos 5.1 is made by Anthropic and GPT-4 by OpenAI. Claude Mythos 5.1 is 47% cheaper than GPT-4 at the headline price ($20.00 / 1M tokens vs $37.50 / 1M tokens). Claude Mythos 5.1 reads more per request: 1M tokens against 8k. Claude Mythos 5.1 is the newer model (September 2026, against March 2023). Only Claude Mythos 5.1 offers vision, reasoning, prompt caching.
How much do Claude Mythos 5.1 and GPT-4 cost per month?
At 20 million input and 5 million output tokens a month, Claude Mythos 5.1 costs $450.00 and GPT-4 costs $900.00, at standard rates.
Which is newer, Claude Mythos 5.1 or GPT-4?
Claude Mythos 5.1 was released on September 2026 and GPT-4 on March 2023.