Skip to main content
BenchLM
Advertise

Model comparison

Claude Sonnet 4.5 vs DeepSeek V4 Flash

Data verified

Head-to-head evidence from 5 shared benchmark results across 4 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

53.61/100
Margin
5.3pts
winning →
58.88/100
3 category wins1 category wins

Public leaderboard positions: Claude Sonnet 4.5 #96 (Estimated); DeepSeek V4 Flash #61 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Sonnet 4.5 and DeepSeek V4 Flash share 5 comparable benchmark results. 4 of 8 categories are comparable. 7 results are unique to Claude Sonnet 4.5; 17 to DeepSeek V4 Flash.

Updated July 23, 2026
Shared results
5
Claude Sonnet 4.5 only
7
DeepSeek V4 Flash only
17
Comparable categories
4 / 8

Pick DeepSeek V4 Flash if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if knowledge is the priority.

Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 4 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

DeepSeek V4 Flash is clearly ahead on the BenchAlign aggregate, 58.88 to 53.61. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

DeepSeek V4 Flash's sharpest advantage is in mathematics, where it averages 40.8 against 11.2. The single biggest benchmark swing on the page is GPQA, 83.4% to 71.2%. Claude Sonnet 4.5 does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.

Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash. That is roughly 53.6x on output cost alone. DeepSeek V4 Flash gives you the larger context window at 1M, compared with 200K for Claude Sonnet 4.5.

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 Sonnet 4.5 and DeepSeek V4 Flash
CategoryClaude Sonnet 4.5ΔDeepSeek V4 Flash
KnowledgeClaude Sonnet 4.583.4Margin← 44.6DeepSeek V4 Flash38.8
MathClaude Sonnet 4.511.2Margin→ 29.6DeepSeek V4 Flash40.8
CodingClaude Sonnet 4.577.2Margin← 13.0DeepSeek V4 Flash64.2
AgenticClaude Sonnet 4.555.4Margin← 6.3DeepSeek V4 Flash49.1
ReasoningClaude Sonnet 4.513.6MarginNo overlapDeepSeek V4 FlashNot measured

Decisive benchmark drivers

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

More
A · Claude Sonnet 4.5B · DeepSeek V4 Flash

  1. GPQA

    Knowledge
    Source ↗
    A 83.4%B 71.2%
    Winner: Claude Sonnet 4.5Δ 12.2
    GPQA: Claude Sonnet 4.5 scored 83.4%; DeepSeek V4 Flash scored 71.2%. Claude Sonnet 4.5 wins this benchmark.

  2. SWE-bench Verified

    Coding
    Source ↗
    A 77.2%B 73.7%
    Winner: Claude Sonnet 4.5Δ 3.5
    SWE-bench Verified: Claude Sonnet 4.5 scored 77.2%; DeepSeek V4 Flash scored 73.7%. Claude Sonnet 4.5 wins this benchmark.

  3. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 50%B 49.1%
    Winner: Claude Sonnet 4.5Δ 0.9
    Terminal-Bench 2.0: Claude Sonnet 4.5 scored 50%; DeepSeek V4 Flash scored 49.1%. Claude Sonnet 4.5 wins this benchmark.

Operational comparison

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

MetricClaude Sonnet 4.5DeepSeek V4 FlashComparison
Input / output priceUSD per 1M tokensClaude Sonnet 4.5$3 input / $15 outputDeepSeek V4 Flash$0.14 input / $0.28 outputDeepSeek V4 Flash has the lower combined listed price.
Generation speedtokens per secondClaude Sonnet 4.5Not availableDeepSeek V4 FlashNot availableA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Sonnet 4.5Not availableDeepSeek V4 FlashNot availableA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Sonnet 4.5200KDeepSeek V4 Flash1MDeepSeek V4 Flash lists the larger context window.

Benchmark Deep Dive

AgenticClaude Sonnet 4.5 wins
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
Terminal-Bench 2.0Source 50%49.1%Claude Sonnet 4.5 leads
OSWorld-VerifiedSource 61.4%—Not comparable
VITA-BenchSource 17.0%—Not comparable
Gert LabsSource 48.51%54.35%DeepSeek V4 Flash leads
JobBenchSource 27.7%—Not comparable
MCP AtlasSource —64%Not comparable
ToolathlonSource —40.7%Not comparable
Claw-EvalSource —57.8%Not comparable
CodingClaude Sonnet 4.5 wins
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
SWE-bench VerifiedSource 77.2%73.7%Claude Sonnet 4.5 leads
SWE-bench ProSource —49.1%Not comparable
SWE MultilingualSource —69.7%Not comparable
Terminal-Bench 2.0Source —49.1%Not comparable
Reasoning
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
ARC-AGI-2Source 13.6%—Not comparable
MRCR 1MSource —37.5%Not comparable
CorpusQA 1MSource —15.5%Not comparable
KnowledgeClaude Sonnet 4.5 wins
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
GPQASource 83.4%71.2%Claude Sonnet 4.5 leads
MMLU-ProSource —83%Not comparable
SimpleQASource —23.1%Not comparable
Chinese-SimpleQASource —71.5%Not comparable
GPQA-DSource —71.2%Not comparable
HLESource —8.1%Not comparable
MathDeepSeek V4 Flash wins
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
AIME 2025Source 87%—Not comparable
FrontierMath v2 (Tiers 1-3)Source 13.495%—Not comparable
FrontierMath v2 (Tier 4)Source 4.167%—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
Multimodal
BenchmarkClaude Sonnet 4.5DeepSeek V4 FlashResult
Design Arena WebsiteSource 12191238DeepSeek V4 Flash leads
Frequently Asked Questions (5)

Which is better, Claude Sonnet 4.5 or DeepSeek V4 Flash?

DeepSeek V4 Flash is ahead on BenchLM's BenchAlign leaderboard, 58.88 to 53.61. The biggest single separator in this matchup is GPQA, where the scores are 83.4% and 71.2%.

Which is better for knowledge tasks, Claude Sonnet 4.5 or DeepSeek V4 Flash?

Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 38.8. Inside this category, GPQA is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Sonnet 4.5 or DeepSeek V4 Flash?

Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 77.2 versus 64.2. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, Claude Sonnet 4.5 or DeepSeek V4 Flash?

DeepSeek V4 Flash has the edge for math in this comparison, averaging 40.8 versus 11.2. Claude Sonnet 4.5 stays close enough that the answer can still flip depending on your workload.

Which is better for agentic tasks, Claude Sonnet 4.5 or DeepSeek V4 Flash?

Claude Sonnet 4.5 has the edge for agentic tasks in this comparison, averaging 55.4 versus 49.1. Inside this category, Gert Labs is the benchmark that creates the most daylight between them.

Related Comparisons

Explore More

Anthropic Compare Pricing Methodology Find Your Best LLM Overall Rankings
Last updated: July 23, 2026

Choose a model with this week’s evidence

Join 2,000+ readers for ranking moves, pricing changes, and the claims that still need proof.

One email each week. Unsubscribe anytime.