Model comparison
Claude Mythos 5 vs GPT-5.1
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Mythos 5 #1 (Supported); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Mythos 5 and GPT-5.1 share 0 comparable benchmark results. 1 of 8 categories are comparable. 15 results are unique to Claude Mythos 5; 21 to GPT-5.1.
Updated July 23, 2026- Shared results
- 0
- Claude Mythos 5 only
- 15
- GPT-5.1 only
- 21
- Comparable categories
- 1 / 8
Pick Claude Mythos 5 if you want the stronger benchmark profile. GPT-5.1 only becomes the better choice if you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Claude Mythos 5 is clearly ahead on the BenchAlign aggregate, 83.93 to 53.65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Mythos 5's sharpest advantage is in mathematics, where it averages 97.6 against 26.4.
Claude Mythos 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $1.25 input / $10.00 output per 1M tokens for GPT-5.1. That is roughly 5.0x on output cost alone. Claude Mythos 5 gives you the larger context window at 1M+, compared with 200K for GPT-5.1.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Mythos 5 | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Mythos 5$10 input / $50 output | GPT-5.1$1.25 input / $10 output | GPT-5.1 has the lower combined listed price. |
| Generation speedtokens per second | Claude Mythos 5Not available | GPT-5.1111 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Mythos 5Not available | GPT-5.157.47 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Mythos 51M+ | GPT-5.1200K | Claude Mythos 5 lists the larger context window. |
Benchmark Deep Dive
Agentic9 benchmarks
| Benchmark | Claude Mythos 5 | GPT-5.1 | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 88% | — | Not comparable |
| OSWorld-VerifiedSource | 85% | — | Not comparable |
| BrowseCompSource | 88% | — | Not comparable |
| ExploitGymSource | 17.5% | — | Not comparable |
| AA Agentic IndexSource | — | 21.0% | Not comparable |
| τ²-bench resultsSource | — | 81.9% | Not comparable |
| Gert LabsSource | — | 41.24% | Not comparable |
| GDPval-AASource | — | 24.4% | Not comparable |
| GDPval-AASource | — | 987 | Not comparable |
Coding6 benchmarks
Reasoning2 benchmarks
Knowledge9 benchmarks
| Benchmark | Claude Mythos 5 | GPT-5.1 | Result |
|---|---|---|---|
| GPQASource | 94.1% | — | Not comparable |
| HLESource | 64.5% | — | Not comparable |
| HLE w/o toolsSource | 59% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 36.9% | Not comparable |
| AA-GPQA DiamondSource | — | 87.3% | Not comparable |
| AA-HLESource | — | 26.5% | Not comparable |
| AA-Omniscience IndexSource | — | 5.6% | Not comparable |
| AA-Omniscience AccuracySource | — | 37.6% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 51.3% | Not comparable |
MathClaude Mythos 5 wins3 benchmarks
Multilingual1 benchmarks
| Benchmark | Claude Mythos 5 | GPT-5.1 | Result |
|---|---|---|---|
| SWE MultilingualSource | 92.2% | — | Not comparable |
Multimodal5 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude Mythos 5 | GPT-5.1 | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 72.9% | Not comparable |
Frequently Asked Questions (2)
Which is better, Claude Mythos 5 or GPT-5.1?
Claude Mythos 5 is ahead on BenchLM's BenchAlign leaderboard, 83.93 to 53.65.
Which is better for math, Claude Mythos 5 or GPT-5.1?
Claude Mythos 5 has the edge for math in this comparison, averaging 97.6 versus 26.4. GPT-5.1 stays close enough that the answer can still flip depending on your workload.
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