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Model comparison

Claude Mythos 5 vs GPT-5.4 nano

Data verified

Head-to-head evidence from 5 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

83.93/100
Margin
17.1pts
← winning
66.79/100
4 category wins0 category wins

Public leaderboard positions: Claude Mythos 5 #1 (Supported); GPT-5.4 nano #25 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Mythos 5 and GPT-5.4 nano share 5 comparable benchmark results. 4 of 8 categories are comparable. 10 results are unique to Claude Mythos 5; 24 to GPT-5.4 nano.

Updated July 23, 2026
Shared results
5
Claude Mythos 5 only
10
GPT-5.4 nano only
24
Comparable categories
4 / 8

Pick Claude Mythos 5 if you want the stronger benchmark profile. GPT-5.4 nano only becomes the better choice if you want the cheaper token bill.

Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 2 evidence categories; 4 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 66.79. 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 21. The single biggest benchmark swing on the page is OSWorld-Verified, 85% to 39%.

Claude Mythos 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $0.20 input / $1.25 output per 1M tokens for GPT-5.4 nano. That is roughly 40.0x on output cost alone. Claude Mythos 5 gives you the larger context window at 1M+, compared with 400K for GPT-5.4 nano.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for Claude Mythos 5 and GPT-5.4 nano
CategoryClaude Mythos 5ΔGPT-5.4 nano
MathClaude Mythos 597.6Margin← 76.6GPT-5.4 nano21.0
AgenticClaude Mythos 587.0Margin← 44.1GPT-5.4 nano42.9
MultimodalClaude Mythos 593.5Margin← 27.4GPT-5.4 nano66.1
KnowledgeClaude Mythos 568.5Margin← 24.7GPT-5.4 nano43.8
CodingClaude Mythos 589.7MarginNo overlapGPT-5.4 nanoNot measured

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · Claude Mythos 5B · GPT-5.4 nano

  1. OSWorld-Verified

    Agentic
    Source ↗
    A 85%B 39%
    Winner: Claude Mythos 5Δ 46
    OSWorld-Verified: Claude Mythos 5 scored 85%; GPT-5.4 nano scored 39%. Claude Mythos 5 wins this benchmark.

  2. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 88%B 46.3%
    Winner: Claude Mythos 5Δ 41.7
    Terminal-Bench 2.0: Claude Mythos 5 scored 88%; GPT-5.4 nano scored 46.3%. Claude Mythos 5 wins this benchmark.

  3. HLE

    Knowledge
    Source ↗
    A 64.5%B 37.7%
    Winner: Claude Mythos 5Δ 26.8
    HLE: Claude Mythos 5 scored 64.5%; GPT-5.4 nano scored 37.7%. Claude Mythos 5 wins this benchmark.

  4. GPQA

    Knowledge
    Source ↗
    A 94.1%B 82.8%
    Winner: Claude Mythos 5Δ 11.3
    GPQA: Claude Mythos 5 scored 94.1%; GPT-5.4 nano scored 82.8%. Claude Mythos 5 wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricClaude Mythos 5GPT-5.4 nanoComparison
Input / output priceUSD per 1M tokensClaude Mythos 5$10 input / $50 outputGPT-5.4 nano$0.2 input / $1.25 outputGPT-5.4 nano has the lower combined listed price.
Generation speedtokens per secondClaude Mythos 5Not availableGPT-5.4 nano191 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Mythos 5Not availableGPT-5.4 nano3.64 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Mythos 51M+GPT-5.4 nano400KClaude Mythos 5 lists the larger context window.

Benchmark Deep Dive

AgenticClaude Mythos 5 wins
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
Terminal-Bench 2.0Source 88%46.3%Claude Mythos 5 leads
OSWorld-VerifiedSource 85%39%Claude Mythos 5 leads
BrowseCompSource 88%—Not comparable
ExploitGymSource 17.5%—Not comparable
MCP AtlasSource —56.1%Not comparable
ToolathlonSource —35.5%Not comparable
τ²-bench resultsSource —76%Not comparable
AA Agentic IndexSource —27.5%Not comparable
APEX-Agents-AASource —24.9%Not comparable
GDPval-AASource —30.0%Not comparable
GDPval-AASource —1100Not comparable
Coding
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
SWE-bench VerifiedSource 95.5%—Not comparable
SWE-bench ProSource 80.3%—Not comparable
Terminal-Bench 2.0Source 88.0%—Not comparable
Vibe Code BenchSource —26.10%Not comparable
AA Coding IndexSource —56.1%Not comparable
AA-SciCodeSource —46.9%Not comparable
Reasoning
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
AA-LCRSource —66.0%Not comparable
CritPtSource —9.3%Not comparable
KnowledgeClaude Mythos 5 wins
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
GPQASource 94.1%82.8%Claude Mythos 5 leads
HLESource 64.5%37.7%Claude Mythos 5 leads
HLE w/o toolsSource 59%24.3%Claude Mythos 5 leads
Artificial Analysis Intelligence IndexSource —38.2%Not comparable
AA-GPQA DiamondSource —81.7%Not comparable
AA-HLESource —26.5%Not comparable
AA-Omniscience IndexSource —-29.5%Not comparable
AA-Omniscience AccuracySource —25.4%Not comparable
AA-Omniscience Hallucination RateSource —73.6%Not comparable
MathClaude Mythos 5 wins
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
USAMO 2026Source 97.6%—Not comparable
FrontierMath v2 (Tiers 1-3)Source —25.860%Not comparable
FrontierMath v2 (Tier 4)Source —6.250%Not comparable
Multilingual
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
SWE MultilingualSource 92.2%—Not comparable
MultimodalClaude Mythos 5 wins
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
SWE-bench MultimodalSource 54.9%—Not comparable
CharXivSource 93.5%—Not comparable
CharXiv w/o toolsSource 88.9%—Not comparable
MMMU-ProSource —66.1%Not comparable
MMMU-Pro w/ PythonSource —69.5%Not comparable
AA-MMMU-ProSource —65.4%Not comparable
Inst. Following
BenchmarkClaude Mythos 5GPT-5.4 nanoResult
AA-IFBenchSource —75.9%Not comparable
Frequently Asked Questions (5)

Which is better, Claude Mythos 5 or GPT-5.4 nano?

Claude Mythos 5 is ahead on BenchLM's BenchAlign leaderboard, 83.93 to 66.79. The biggest single separator in this matchup is OSWorld-Verified, where the scores are 85% and 39%.

Which is better for knowledge tasks, Claude Mythos 5 or GPT-5.4 nano?

Claude Mythos 5 has the edge for knowledge tasks in this comparison, averaging 68.5 versus 43.8. Inside this category, HLE w/o tools is the benchmark that creates the most daylight between them.

Which is better for math, Claude Mythos 5 or GPT-5.4 nano?

Claude Mythos 5 has the edge for math in this comparison, averaging 97.6 versus 21. GPT-5.4 nano stays close enough that the answer can still flip depending on your workload.

Which is better for agentic tasks, Claude Mythos 5 or GPT-5.4 nano?

Claude Mythos 5 has the edge for agentic tasks in this comparison, averaging 87 versus 42.9. Inside this category, OSWorld-Verified is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Claude Mythos 5 or GPT-5.4 nano?

Claude Mythos 5 has the edge for multimodal and grounded tasks in this comparison, averaging 93.5 versus 66.1. GPT-5.4 nano stays close enough that the answer can still flip depending on your workload.

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