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Model comparison

Claude Mythos 5 vs Grok 4.3

Data verified

Head-to-head evidence from 2 shared benchmark results across 1 category. Overall scores shown here use the public BenchAlign v5 ranking lane.

83.93/100
Margin
18.8pts
← winning
65.1/100
3 category wins0 category wins

Public leaderboard positions: Claude Mythos 5 #1 (Supported); Grok 4.3 #31 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Mythos 5 and Grok 4.3 share 2 comparable benchmark results. 3 of 8 categories are comparable. 13 results are unique to Claude Mythos 5; 23 to Grok 4.3.

Updated July 23, 2026
Shared results
2
Claude Mythos 5 only
13
Grok 4.3 only
23
Comparable categories
3 / 8

Pick Claude Mythos 5 if you want the stronger benchmark profile. Grok 4.3 only becomes the better choice if you want the cheaper token bill.

Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 1 evidence category; 3 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 65.1. 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 coding, where it averages 89.7 against 47.3. The single biggest benchmark swing on the page is HLE, 64.5% to 35%.

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 / $2.50 output per 1M tokens for Grok 4.3. That is roughly 20.0x on output cost alone. Claude Mythos 5 gives you the larger context window at 1M+, compared with 1M for Grok 4.3.

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 Grok 4.3
CategoryClaude Mythos 5ΔGrok 4.3
CodingClaude Mythos 589.7Margin← 42.4Grok 4.347.3
KnowledgeClaude Mythos 568.5Margin← 26.1Grok 4.342.4
MultimodalClaude Mythos 593.5Margin← 15.4Grok 4.378.1
AgenticClaude Mythos 587.0MarginNo overlapGrok 4.3Not measured
MathClaude Mythos 597.6MarginNo overlapGrok 4.3Not measured
Inst. FollowingClaude Mythos 5Not measuredMarginNo overlapGrok 4.381.3

Decisive benchmark drivers

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

More
A · Claude Mythos 5B · Grok 4.3

  1. HLE

    Knowledge
    Source ↗
    A 64.5%B 35%
    Winner: Claude Mythos 5Δ 29.5
    HLE: Claude Mythos 5 scored 64.5%; Grok 4.3 scored 35%. Claude Mythos 5 wins this benchmark.

  2. GPQA

    Knowledge
    Source ↗
    A 94.1%B 90.1%
    Winner: Claude Mythos 5Δ 4
    GPQA: Claude Mythos 5 scored 94.1%; Grok 4.3 scored 90.1%. 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 5Grok 4.3Comparison
Input / output priceUSD per 1M tokensClaude Mythos 5$10 input / $50 outputGrok 4.3$1.25 input / $2.5 outputGrok 4.3 has the lower combined listed price.
Generation speedtokens per secondClaude Mythos 5Not availableGrok 4.3209 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Mythos 5Not availableGrok 4.312.36 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Mythos 51M+Grok 4.31MClaude Mythos 5 lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Mythos 5Grok 4.3Result
Terminal-Bench 2.0Source 88%—Not comparable
OSWorld-VerifiedSource 85%—Not comparable
BrowseCompSource 88%—Not comparable
ExploitGymSource 17.5%—Not comparable
τ²-bench resultsSource —97.7%Not comparable
GDPval-AASource —29.2%Not comparable
AA Agentic IndexSource —24.1%Not comparable
APEX-Agents-AASource —17.0%Not comparable
GDPval-AASource —1085Not comparable
Gert LabsSource —43.86%Not comparable
ResearchClawBenchSource —12.4%Not comparable
CodingClaude Mythos 5 wins
BenchmarkClaude Mythos 5Grok 4.3Result
SWE-bench VerifiedSource 95.5%—Not comparable
SWE-bench ProSource 80.3%—Not comparable
Terminal-Bench 2.0Source 88.0%—Not comparable
SciCodeSource —47.3%Not comparable
AA Coding IndexSource —42.3%Not comparable
AA-SciCodeSource —47.3%Not comparable
Reasoning
BenchmarkClaude Mythos 5Grok 4.3Result
AA-LCRSource —64.3%Not comparable
CritPtSource —8.0%Not comparable
KnowledgeClaude Mythos 5 wins
BenchmarkClaude Mythos 5Grok 4.3Result
GPQASource 94.1%90.1%Claude Mythos 5 leads
HLESource 64.5%35%Claude Mythos 5 leads
HLE w/o toolsSource 59%—Not comparable
Artificial Analysis Intelligence IndexSource —37.6%Not comparable
AA-Omniscience AccuracySource —34.6%Not comparable
AA-Omniscience Hallucination RateSource —25.0%Not comparable
AA-GPQA DiamondSource —90.1%Not comparable
AA-HLESource —35.0%Not comparable
AA-Omniscience IndexSource —18.3%Not comparable
Math
BenchmarkClaude Mythos 5Grok 4.3Result
USAMO 2026Source 97.6%—Not comparable
Multilingual
BenchmarkClaude Mythos 5Grok 4.3Result
SWE MultilingualSource 92.2%—Not comparable
MultimodalClaude Mythos 5 wins
BenchmarkClaude Mythos 5Grok 4.3Result
SWE-bench MultimodalSource 54.9%—Not comparable
CharXivSource 93.5%—Not comparable
CharXiv w/o toolsSource 88.9%—Not comparable
MMMU-ProSource —78.1%Not comparable
Design Arena WebsiteSource —1225Not comparable
AA-MMMU-ProSource —78.1%Not comparable
Inst. Following
BenchmarkClaude Mythos 5Grok 4.3Result
IFBenchSource —81.3%Not comparable
AA-IFBenchSource —81.3%Not comparable
Frequently Asked Questions (4)

Which is better, Claude Mythos 5 or Grok 4.3?

Claude Mythos 5 is ahead on BenchLM's BenchAlign leaderboard, 83.93 to 65.1. The biggest single separator in this matchup is HLE, where the scores are 64.5% and 35%.

Which is better for knowledge tasks, Claude Mythos 5 or Grok 4.3?

Claude Mythos 5 has the edge for knowledge tasks in this comparison, averaging 68.5 versus 42.4. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Mythos 5 or Grok 4.3?

Claude Mythos 5 has the edge for coding in this comparison, averaging 89.7 versus 47.3. Grok 4.3 stays close enough that the answer can still flip depending on your workload.

Which is better for multimodal and grounded tasks, Claude Mythos 5 or Grok 4.3?

Claude Mythos 5 has the edge for multimodal and grounded tasks in this comparison, averaging 93.5 versus 78.1. Grok 4.3 stays close enough that the answer can still flip depending on your workload.

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