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Model comparison

Claude Mythos 5 vs DeepSeek V4 Flash

Data verified

Head-to-head evidence from 6 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

83.93/100
Margin
25.1pts
← winning
58.88/100
4 category wins0 category wins

Public leaderboard positions: Claude Mythos 5 #1 (Supported); DeepSeek V4 Flash #61 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Mythos 5 and DeepSeek V4 Flash share 6 comparable benchmark results. 4 of 8 categories are comparable. 9 results are unique to Claude Mythos 5; 16 to DeepSeek V4 Flash.

Updated July 23, 2026
Shared results
6
Claude Mythos 5 only
9
DeepSeek V4 Flash only
16
Comparable categories
4 / 8

Pick Claude Mythos 5 if you want the stronger benchmark profile. DeepSeek V4 Flash only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.

Confidence note. This is a partial-evidence comparison with 6 shared benchmark results across 3 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 58.88. 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 40.8. The single biggest benchmark swing on the page is HLE, 64.5% to 8.1%.

Claude Mythos 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash. That is roughly 178.6x on output cost alone. Claude Mythos 5 is the reasoning model in the pair, while DeepSeek V4 Flash is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Claude Mythos 5 gives you the larger context window at 1M+, compared with 1M for DeepSeek V4 Flash.

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 DeepSeek V4 Flash
CategoryClaude Mythos 5ΔDeepSeek V4 Flash
MathClaude Mythos 597.6Margin← 56.8DeepSeek V4 Flash40.8
AgenticClaude Mythos 587.0Margin← 37.9DeepSeek V4 Flash49.1
KnowledgeClaude Mythos 568.5Margin← 29.7DeepSeek V4 Flash38.8
CodingClaude Mythos 589.7Margin← 25.5DeepSeek V4 Flash64.2
MultimodalClaude Mythos 593.5MarginNo overlapDeepSeek V4 FlashNot measured

Decisive benchmark drivers

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

More
A · Claude Mythos 5B · DeepSeek V4 Flash

  1. HLE

    Knowledge
    Source ↗
    A 64.5%B 8.1%
    Winner: Claude Mythos 5Δ 56.4
    HLE: Claude Mythos 5 scored 64.5%; DeepSeek V4 Flash scored 8.1%. Claude Mythos 5 wins this benchmark.

  2. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 88%B 49.1%
    Winner: Claude Mythos 5Δ 38.9
    Terminal-Bench 2.0: Claude Mythos 5 scored 88%; DeepSeek V4 Flash scored 49.1%. Claude Mythos 5 wins this benchmark.

  3. SWE-bench Pro

    Coding
    Source ↗
    A 80.3%B 49.1%
    Winner: Claude Mythos 5Δ 31.2
    SWE-bench Pro: Claude Mythos 5 scored 80.3%; DeepSeek V4 Flash scored 49.1%. Claude Mythos 5 wins this benchmark.

  4. GPQA

    Knowledge
    Source ↗
    A 94.1%B 71.2%
    Winner: Claude Mythos 5Δ 22.9
    GPQA: Claude Mythos 5 scored 94.1%; DeepSeek V4 Flash scored 71.2%. Claude Mythos 5 wins this benchmark.

  5. SWE-bench Verified

    Coding
    Source ↗
    A 95.5%B 73.7%
    Winner: Claude Mythos 5Δ 21.8
    SWE-bench Verified: Claude Mythos 5 scored 95.5%; DeepSeek V4 Flash scored 73.7%. 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 5DeepSeek V4 FlashComparison
Input / output priceUSD per 1M tokensClaude Mythos 5$10 input / $50 outputDeepSeek V4 Flash$0.14 input / $0.28 outputDeepSeek V4 Flash has the lower combined listed price.
Generation speedtokens per secondClaude Mythos 5Not availableDeepSeek V4 FlashNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Mythos 5Not availableDeepSeek V4 FlashNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Mythos 51M+DeepSeek V4 Flash1MClaude Mythos 5 lists the larger context window.

Benchmark Deep Dive

AgenticClaude Mythos 5 wins
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
Terminal-Bench 2.0Source 88%49.1%Claude Mythos 5 leads
OSWorld-VerifiedSource 85%—Not comparable
BrowseCompSource 88%—Not comparable
ExploitGymSource 17.5%—Not comparable
MCP AtlasSource —64%Not comparable
ToolathlonSource —40.7%Not comparable
Claw-EvalSource —57.8%Not comparable
Gert LabsSource —54.35%Not comparable
CodingClaude Mythos 5 wins
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
SWE-bench VerifiedSource 95.5%73.7%Claude Mythos 5 leads
SWE-bench ProSource 80.3%49.1%Claude Mythos 5 leads
Terminal-Bench 2.0Source 88.0%49.1%Claude Mythos 5 leads
SWE MultilingualSource —69.7%Not comparable
Reasoning
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
MRCR 1MSource —37.5%Not comparable
CorpusQA 1MSource —15.5%Not comparable
KnowledgeClaude Mythos 5 wins
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
GPQASource 94.1%71.2%Claude Mythos 5 leads
HLESource 64.5%8.1%Claude Mythos 5 leads
HLE w/o toolsSource 59%—Not comparable
MMLU-ProSource —83%Not comparable
SimpleQASource —23.1%Not comparable
Chinese-SimpleQASource —71.5%Not comparable
GPQA-DSource —71.2%Not comparable
MathClaude Mythos 5 wins
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
USAMO 2026Source 97.6%—Not comparable
HMMT Feb 2026Source —40.8%Not comparable
IMOAnswerBenchSource —41.9%Not comparable
ApexSource —1.0%Not comparable
Apex ShortlistSource —9.3%Not comparable
Multilingual
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
SWE MultilingualSource 92.2%—Not comparable
Multimodal
BenchmarkClaude Mythos 5DeepSeek V4 FlashResult
SWE-bench MultimodalSource 54.9%—Not comparable
CharXivSource 93.5%—Not comparable
CharXiv w/o toolsSource 88.9%—Not comparable
Design Arena WebsiteSource —1238Not comparable
Frequently Asked Questions (5)

Which is better, Claude Mythos 5 or DeepSeek V4 Flash?

Claude Mythos 5 is ahead on BenchLM's BenchAlign leaderboard, 83.93 to 58.88. The biggest single separator in this matchup is HLE, where the scores are 64.5% and 8.1%.

Which is better for knowledge tasks, Claude Mythos 5 or DeepSeek V4 Flash?

Claude Mythos 5 has the edge for knowledge tasks in this comparison, averaging 68.5 versus 38.8. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Mythos 5 or DeepSeek V4 Flash?

Claude Mythos 5 has the edge for coding in this comparison, averaging 89.7 versus 64.2. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for math, Claude Mythos 5 or DeepSeek V4 Flash?

Claude Mythos 5 has the edge for math in this comparison, averaging 97.6 versus 40.8. DeepSeek V4 Flash stays close enough that the answer can still flip depending on your workload.

Which is better for agentic tasks, Claude Mythos 5 or DeepSeek V4 Flash?

Claude Mythos 5 has the edge for agentic tasks in this comparison, averaging 87 versus 49.1. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

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