Model comparison
DeepSeek V4 Flash vs GPT-5.1
Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: DeepSeek V4 Flash #61 (Estimated); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. DeepSeek V4 Flash and GPT-5.1 share 2 comparable benchmark results. 1 of 8 categories are comparable. 20 results are unique to DeepSeek V4 Flash; 19 to GPT-5.1.
Updated July 23, 2026- Shared results
- 2
- DeepSeek V4 Flash only
- 20
- GPT-5.1 only
- 19
- Comparable categories
- 1 / 8
Pick DeepSeek V4 Flash if you want the stronger benchmark profile. GPT-5.1 only becomes the better choice if you want the stronger reasoning-first profile.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 evidence categories; 1 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 53.65. 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 26.4.
GPT-5.1 is also the more expensive model on tokens at $1.25 input / $10.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash. That is roughly 35.7x on output cost alone. GPT-5.1 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. DeepSeek V4 Flash gives you the larger context window at 1M, compared with 200K for GPT-5.1.
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 | DeepSeek V4 Flash | Δ | GPT-5.1 |
|---|---|---|---|
| Math | DeepSeek V4 Flash40.8 | Margin← 14.4 | GPT-5.126.4 |
| Agentic | DeepSeek V4 Flash49.1 | MarginNo overlap | GPT-5.1Not measured |
| Coding | DeepSeek V4 Flash64.2 | MarginNo overlap | GPT-5.1Not measured |
| Knowledge | DeepSeek V4 Flash38.8 | MarginNo overlap | GPT-5.1Not measured |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | DeepSeek V4 Flash | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | DeepSeek V4 Flash$0.14 input / $0.28 output | GPT-5.1$1.25 input / $10 output | DeepSeek V4 Flash has the lower combined listed price. |
| Generation speedtokens per second | DeepSeek V4 FlashNot available | GPT-5.1111 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | DeepSeek V4 FlashNot available | GPT-5.157.47 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | DeepSeek V4 Flash1M | GPT-5.1200K | DeepSeek V4 Flash lists the larger context window. |
Benchmark Deep Dive
Agentic9 benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.1 | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 49.1% | — | Not comparable |
| MCP AtlasSource | 64% | — | Not comparable |
| ToolathlonSource | 40.7% | — | Not comparable |
| Claw-EvalSource | 57.8% | — | Not comparable |
| Gert LabsSource | 54.35% | 41.24% | DeepSeek V4 Flash leads |
| AA Agentic IndexSource | — | 21.0% | Not comparable |
| τ²-bench resultsSource | — | 81.9% | Not comparable |
| GDPval-AASource | — | 24.4% | Not comparable |
| GDPval-AASource | — | 987 | Not comparable |
Coding7 benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.1 | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 73.7% | — | Not comparable |
| SWE-bench ProSource | 49.1% | — | Not comparable |
| SWE MultilingualSource | 69.7% | — | Not comparable |
| Terminal-Bench 2.0Source | 49.1% | — | Not comparable |
| Vibe Code BenchSource | — | 24.61% | Not comparable |
| AA Coding IndexSource | — | 49.4% | Not comparable |
| AA-SciCodeSource | — | 43.3% | Not comparable |
Reasoning4 benchmarks
Knowledge12 benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.1 | Result |
|---|---|---|---|
| MMLU-ProSource | 83% | — | Not comparable |
| SimpleQASource | 23.1% | — | Not comparable |
| Chinese-SimpleQASource | 71.5% | — | Not comparable |
| GPQASource | 71.2% | — | Not comparable |
| GPQA-DSource | 71.2% | — | Not comparable |
| HLESource | 8.1% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 36.9% | Not comparable |
| AA-GPQA DiamondSource | — | 87.3% | Not comparable |
| AA-HLESource | — | 26.5% | Not comparable |
| AA-Omniscience IndexSource | — | 5.6% | Not comparable |
| AA-Omniscience AccuracySource | — | 37.6% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 51.3% | Not comparable |
MathDeepSeek V4 Flash wins6 benchmarks
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.1 | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 72.9% | Not comparable |
Frequently Asked Questions (2)
Which is better, DeepSeek V4 Flash or GPT-5.1?
DeepSeek V4 Flash is ahead on BenchLM's BenchAlign leaderboard, 58.88 to 53.65.
Which is better for math, DeepSeek V4 Flash or GPT-5.1?
DeepSeek V4 Flash has the edge for math in this comparison, averaging 40.8 versus 26.4. GPT-5.1 stays close enough that the answer can still flip depending on your workload.
Related Comparisons
Explore More
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.