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Model comparison

DeepSeek V4 Flash (Max) vs GPT-5.3 Codex

Data verified

Head-to-head evidence from 15 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

N/A
No comparison
66.69/100
1 category wins1 category wins

Public leaderboard positions: DeepSeek V4 Flash (Max) unranked (Not scored); GPT-5.3 Codex #26 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. DeepSeek V4 Flash (Max) and GPT-5.3 Codex share 15 comparable benchmark results. 2 of 8 categories are comparable. 30 results are unique to DeepSeek V4 Flash (Max); 6 to GPT-5.3 Codex.

Updated July 23, 2026
Shared results
15
DeepSeek V4 Flash (Max) only
30
GPT-5.3 Codex only
6
Comparable categories
2 / 8

Treat this as a split decision. DeepSeek V4 Flash (Max) makes more sense if coding is the priority or you want the cheaper token bill; GPT-5.3 Codex is the better fit if agentic is the priority.

Confidence note. This is a partial-evidence comparison with 15 shared benchmark results across 6 evidence categories; 2 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

DeepSeek V4 Flash (Max) and GPT-5.3 Codex finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.

GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash (Max). That is roughly 50.0x on output cost alone. DeepSeek V4 Flash (Max) gives you the larger context window at 1M, compared with 400K for GPT-5.3 Codex.

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 DeepSeek V4 Flash (Max) and GPT-5.3 Codex
CategoryDeepSeek V4 Flash (Max)ΔGPT-5.3 Codex
AgenticDeepSeek V4 Flash (Max)63.8Margin→ 7.6GPT-5.3 Codex71.4
CodingDeepSeek V4 Flash (Max)68.8Margin← 1.6GPT-5.3 Codex67.2
KnowledgeDeepSeek V4 Flash (Max)55.3MarginNo overlapGPT-5.3 CodexNot measured
MathDeepSeek V4 Flash (Max)94.8MarginNo overlapGPT-5.3 CodexNot measured

Decisive benchmark drivers

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

More
A · DeepSeek V4 Flash (Max)B · GPT-5.3 Codex

  1. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 56.9%B 77.3%
    Winner: GPT-5.3 CodexΔ 20.4
    Terminal-Bench 2.0: DeepSeek V4 Flash (Max) scored 56.9%; GPT-5.3 Codex scored 77.3%. GPT-5.3 Codex wins this benchmark.

  2. SWE-bench Verified

    Coding
    Source ↗
    A 79%B 85%
    Winner: GPT-5.3 CodexΔ 6
    SWE-bench Verified: DeepSeek V4 Flash (Max) scored 79%; GPT-5.3 Codex scored 85%. GPT-5.3 Codex wins this benchmark.

  3. SWE-bench Pro

    Coding
    Source ↗
    A 52.6%B 56.8%
    Winner: GPT-5.3 CodexΔ 4.2
    SWE-bench Pro: DeepSeek V4 Flash (Max) scored 52.6%; GPT-5.3 Codex scored 56.8%. GPT-5.3 Codex wins this benchmark.

Operational comparison

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

MetricDeepSeek V4 Flash (Max)GPT-5.3 CodexComparison
Input / output priceUSD per 1M tokensDeepSeek V4 Flash (Max)$0.14 input / $0.28 outputGPT-5.3 Codex$1.75 input / $14 outputDeepSeek V4 Flash (Max) has the lower combined listed price.
Generation speedtokens per secondDeepSeek V4 Flash (Max)Not availableGPT-5.3 Codex79 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenDeepSeek V4 Flash (Max)Not availableGPT-5.3 Codex88.26 sA complete latency comparison is not available.
Context windowmaximum listed tokensDeepSeek V4 Flash (Max)1MGPT-5.3 Codex400KDeepSeek V4 Flash (Max) lists the larger context window.

Benchmark Deep Dive

AgenticGPT-5.3 Codex wins
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
Terminal-Bench 2.0Source 56.9%77.3%GPT-5.3 Codex leads
BrowseCompSource 73.2%—Not comparable
HLE w/ toolsSource 45.1%—Not comparable
MCP AtlasSource 69%—Not comparable
GDPval-AASource 1189—Not comparable
ToolathlonSource 47.8%—Not comparable
AA Agentic IndexSource 31.1%—Not comparable
τ²-bench resultsSource 95%86%DeepSeek V4 Flash (Max) leads
GDPval-AASource 34.4%—Not comparable
AA BriefcaseSource 831—Not comparable
AA EnterpriseOps-GymSource 39.6%—Not comparable
AA Harvey LABSource 81.3%—Not comparable
AA ITBenchSource 31.5%—Not comparable
AA Tau3 BankingSource 22.9%—Not comparable
terminalBenchHardSource 35.6%—Not comparable
OSWorld-VerifiedSource —64.7%Not comparable
Gert LabsSource —57.47%Not comparable
JobBenchSource —33.7%Not comparable
CodingDeepSeek V4 Flash (Max) wins
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
CodeforcesSource 3052.0—Not comparable
SWE-bench VerifiedSource 79%85%GPT-5.3 Codex leads
SWE-bench ProSource 52.6%56.8%GPT-5.3 Codex leads
SWE MultilingualSource 73.3%—Not comparable
Terminal-Bench 2.0Source 56.9%—Not comparable
AA Coding IndexSource 56.2%—Not comparable
AA-SciCodeSource 44.9%53.2%GPT-5.3 Codex leads
SWE-RebenchSource —58.2%Not comparable
Vibe Code BenchSource —61.77%Not comparable
Reasoning
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
MRCR 1MSource 78.7%—Not comparable
CorpusQA 1MSource 60.5%—Not comparable
AA-LCRSource 63.0%74.0%GPT-5.3 Codex leads
CritPtSource 7.1%16.9%GPT-5.3 Codex leads
Knowledge
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
MMLU-ProSource 86.2%—Not comparable
SimpleQASource 34.1%—Not comparable
Chinese-SimpleQASource 78.9%—Not comparable
GPQASource 88.1%—Not comparable
GPQA-DSource 88.1%—Not comparable
HLESource 34.8%—Not comparable
Artificial Analysis Intelligence IndexSource 40.3%44.3%GPT-5.3 Codex leads
AA-GPQA DiamondSource 89.4%91.5%GPT-5.3 Codex leads
AA-HLESource 32.1%39.9%GPT-5.3 Codex leads
AA-Omniscience IndexSource -22.9%9.9%GPT-5.3 Codex leads
AA-Omniscience AccuracySource 37.2%51.8%GPT-5.3 Codex leads
AA-Omniscience Hallucination RateSource 95.8%86.9%GPT-5.3 Codex leads
AA Openness IndexSource 50.0%—Not comparable
Math
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
HMMT Feb 2026Source 94.8%—Not comparable
IMOAnswerBenchSource 88.4%—Not comparable
ApexSource 33.0%—Not comparable
Apex ShortlistSource 85.7%—Not comparable
Multimodal
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
Design Arena WebsiteSource 12381193DeepSeek V4 Flash (Max) leads
AA-MMMU-ProSource —78.5%Not comparable
Inst. Following
BenchmarkDeepSeek V4 Flash (Max)GPT-5.3 CodexResult
AA-IFBenchSource 79.2%75.4%DeepSeek V4 Flash (Max) leads
Frequently Asked Questions (3)

Which is better, DeepSeek V4 Flash (Max) or GPT-5.3 Codex?

DeepSeek V4 Flash (Max) and GPT-5.3 Codex are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.

Which is better for coding, DeepSeek V4 Flash (Max) or GPT-5.3 Codex?

DeepSeek V4 Flash (Max) has the edge for coding in this comparison, averaging 68.8 versus 67.2. Inside this category, AA-SciCode is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, DeepSeek V4 Flash (Max) or GPT-5.3 Codex?

GPT-5.3 Codex has the edge for agentic tasks in this comparison, averaging 71.4 versus 63.8. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

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