Model comparison
Claude Sonnet 4.5 vs DeepSeek V4 Flash (High)
Head-to-head evidence from 4 shared benchmark results across 4 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Sonnet 4.5 #96 (Estimated); DeepSeek V4 Flash (High) #92 (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 (High) share 4 comparable benchmark results. 4 of 8 categories are comparable. 8 results are unique to Claude Sonnet 4.5; 34 to DeepSeek V4 Flash (High).
Updated July 23, 2026- Shared results
- 4
- Claude Sonnet 4.5 only
- 8
- DeepSeek V4 Flash (High) only
- 34
- Comparable categories
- 4 / 8
Pick DeepSeek V4 Flash (High) if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if knowledge is the priority or you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 4 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 (High) has the cleaner BenchAlign overall profile here, landing at 53.95 versus 53.61. It is a real lead, but still close enough that category-level strengths matter more than the headline number.
DeepSeek V4 Flash (High)'s sharpest advantage is in mathematics, where it averages 91.9 against 11.2. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 50% to 56.6%. 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 (High). That is roughly 53.6x on output cost alone. DeepSeek V4 Flash (High) is the reasoning model in the pair, while Claude Sonnet 4.5 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. DeepSeek V4 Flash (High) 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 | Claude Sonnet 4.5 | Δ | DeepSeek V4 Flash (High) |
|---|---|---|---|
| Math | Claude Sonnet 4.511.2 | Margin→ 80.7 | DeepSeek V4 Flash (High)91.9 |
| Knowledge | Claude Sonnet 4.583.4 | Margin← 31.3 | DeepSeek V4 Flash (High)52.1 |
| Coding | Claude Sonnet 4.577.2 | Margin← 8.7 | DeepSeek V4 Flash (High)68.5 |
| Agentic | Claude Sonnet 4.555.4 | Margin← 0.1 | DeepSeek V4 Flash (High)55.3 |
| Reasoning | Claude Sonnet 4.513.6 | MarginNo overlap | DeepSeek V4 Flash (High)Not measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
Terminal-Bench 2.0
AgenticA 50%B 56.6%Winner: DeepSeek V4 Flash (High)Δ 6.6Terminal-Bench 2.0: Claude Sonnet 4.5 scored 50%; DeepSeek V4 Flash (High) scored 56.6%. DeepSeek V4 Flash (High) wins this benchmark. - Source ↗
GPQA
KnowledgeA 83.4%B 87.4%Winner: DeepSeek V4 Flash (High)Δ 4GPQA: Claude Sonnet 4.5 scored 83.4%; DeepSeek V4 Flash (High) scored 87.4%. DeepSeek V4 Flash (High) wins this benchmark. - Source ↗
SWE-bench Verified
CodingA 77.2%B 78.6%Winner: DeepSeek V4 Flash (High)Δ 1.4SWE-bench Verified: Claude Sonnet 4.5 scored 77.2%; DeepSeek V4 Flash (High) scored 78.6%. DeepSeek V4 Flash (High) wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Sonnet 4.5$3 input / $15 output | DeepSeek V4 Flash (High)$0.14 input / $0.28 output | DeepSeek V4 Flash (High) has the lower combined listed price. |
| Generation speedtokens per second | Claude Sonnet 4.5Not available | DeepSeek V4 Flash (High)Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Sonnet 4.5Not available | DeepSeek V4 Flash (High)Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Sonnet 4.5200K | DeepSeek V4 Flash (High)1M | DeepSeek V4 Flash (High) lists the larger context window. |
Benchmark Deep Dive
AgenticClaude Sonnet 4.5 wins13 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 50% | 56.6% | DeepSeek V4 Flash (High) leads |
| OSWorld-VerifiedSource | 61.4% | — | Not comparable |
| VITA-BenchSource | 17.0% | — | Not comparable |
| Gert LabsSource | 48.51% | — | Not comparable |
| JobBenchSource | 27.7% | — | Not comparable |
| BrowseCompSource | — | 53.5% | Not comparable |
| HLE w/ toolsSource | — | 40.3% | Not comparable |
| MCP AtlasSource | — | 67.4% | Not comparable |
| ToolathlonSource | — | 43.5% | Not comparable |
| τ²-bench resultsSource | — | 95.6% | Not comparable |
| AA Agentic IndexSource | — | 28.2% | Not comparable |
| GDPval-AASource | — | 32.4% | Not comparable |
| GDPval-AASource | — | 1147 | Not comparable |
CodingClaude Sonnet 4.5 wins7 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 77.2% | 78.6% | DeepSeek V4 Flash (High) leads |
| CodeforcesSource | — | 2816.0 | Not comparable |
| SWE-bench ProSource | — | 52.3% | Not comparable |
| SWE MultilingualSource | — | 70.2% | Not comparable |
| Terminal-Bench 2.0Source | — | 56.6% | Not comparable |
| AA-SciCodeSource | — | 42.0% | Not comparable |
| AA Coding IndexSource | — | 52.0% | Not comparable |
Reasoning5 benchmarks
KnowledgeClaude Sonnet 4.5 wins12 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| GPQASource | 83.4% | 87.4% | DeepSeek V4 Flash (High) leads |
| MMLU-ProSource | — | 86.4% | Not comparable |
| SimpleQASource | — | 28.9% | Not comparable |
| Chinese-SimpleQASource | — | 73.2% | Not comparable |
| GPQA-DSource | — | 87.4% | Not comparable |
| HLESource | — | 29.4% | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 37.5% | Not comparable |
| AA-GPQA DiamondSource | — | 86.7% | Not comparable |
| AA-HLESource | — | 27.8% | Not comparable |
| AA-Omniscience IndexSource | — | -22.3% | Not comparable |
| AA-Omniscience AccuracySource | — | 35.5% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 89.7% | Not comparable |
MathDeepSeek V4 Flash (High) wins7 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| 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 | — | 91.9% | Not comparable |
| IMOAnswerBenchSource | — | 85.1% | Not comparable |
| ApexSource | — | 19.1% | Not comparable |
| Apex ShortlistSource | — | 72.1% | Not comparable |
Multimodal1 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| Design Arena WebsiteSource | 1219 | 1238 | DeepSeek V4 Flash (High) leads |
Inst. Following1 benchmarks
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4 Flash (High) | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 73.5% | Not comparable |
Frequently Asked Questions (5)
Which is better, Claude Sonnet 4.5 or DeepSeek V4 Flash (High)?
DeepSeek V4 Flash (High) is ahead on BenchLM's BenchAlign leaderboard, 53.95 to 53.61. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 50% and 56.6%.
Which is better for knowledge tasks, Claude Sonnet 4.5 or DeepSeek V4 Flash (High)?
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 52.1. 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 (High)?
Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 77.2 versus 68.5. 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 (High)?
DeepSeek V4 Flash (High) has the edge for math in this comparison, averaging 91.9 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 (High)?
Claude Sonnet 4.5 has the edge for agentic tasks in this comparison, averaging 55.4 versus 55.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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