DeepSeek V4.1 Flash Nears Frontier Models at a Fraction of the Cost, Independent Tests Show

DeepSeek V4.1 Flash, along with the V4.1 Flash Vision Beta opened the same day, has undergone multiple rounds of independent testing since release. The consensus is that it approaches—and in some cases matches—frontier closed models at roughly 1/30 to 1/70 of their cost, corroborated by Artificial Analysis ranking it 6th of 113 models.

Confirmed

• Artificial Analysis benchmark (reasoning version, Max Effort): Intelligence Index 40, ranked 6th of 113 models, 190 tokens/s throughput; open weights, released September 2026.
• Design comparison by NFTChen: 81.2 points, 98% of GPT-6 Astra's 82.7, above Claude Fable 5.1's 80.3, at 1.4% of Astra's cost; similar figures reported by OpenDesign Arena (via uxl) and OpenDesignHQ (via ChrisUniverse, authenticity unverified).
• Security benchmark by pilvar222: re-discovers 65.6% of recent CVEs in a single run (prior version 55.2%), 84.4% at pass@3 (prior 75%), matching frontier models.
• Bug-fixing test by Pawel Huryn: 105 hidden real bugs across 2 repos; V4.1 Flash reaches the Pareto frontier at 3.5% of Opus's cost (1/28). Reference: Opus 5 (max) 27 bugs at $51.33, Grok 4.6 (max) 27 at $16.96; sander's retelling cites 24 points for V4.1 Flash.
• Knowledge-work evaluation by himanshustwts: 22 internal tasks across engineering, operations, finance, healthcare; 15/21 passes, near SOTA at 2% of competitors' cost; entire run cost $0.34 with GPT-5.5 as judge and 120+ validators per task.
• Vision: Reddit user cheezeerd compared V4.1 Flash Vision Beta vs V4 Flash Vision on 5 tasks on launch day; new version clearly better and more reliable, with lower API pricing.
• Terminal agents and pricing: via Cline (retold by dejavucoder), V4.1-Flash surpassed V4-Pro 0813 on Terminal-Bench within a month of release; pricing from $0.30 per million input tokens, 1/20 of Opus.
• Local deployment: a developer (via TheZachMueller) ran full-precision DeepSeek 4.1 Flash with the DSpark engine at 200 TPS on 4 Apple Max-Q chips with only 64GB system memory, key trick being handling of the 200GB Engram.

Unconfirmed

• Apart from the Artificial Analysis ranking, all results come from third-party individual or team tests with varying samples and methodologies; OpenDesignHQ's benchmark is unverified; the Terminal-Bench claim is second-hand via Cline; the Mac 200 TPS figure is a single developer's report without official metrics or large-scale replication.

Why it matters

• Independent tests across diverse task types mutually corroborate the cost-performance claim rather than relying on a single leaderboard, with Artificial Analysis providing neutral quantitative backing.
• If reproducible, a near-frontier model at ultra-low prices would compress frontier closed-model pricing and lower migration barriers for developers and enterprises.
• Full-precision high-speed operation on consumer Apple hardware adds appeal for local, private deployment scenarios.

2026-09-09 ~ 2026-09-11 · 15 related posts

Full story(18 episodes)→

• Episode 1: DeepSeek V4.1 Flash Opens Limited Internal Beta with New Architecture and Native Multimodality(2026-09-08, 18 posts)
• Episode 2: DeepSeek V4.1 Flash Tested: Blazing 350 Tokens/s but Still Experimental(2026-09-08, 2 posts)
• Episode 3: DeepSeek cuts V4-Flash API prices with new peak/off-peak billing from Sept 10(2026-09-08, 6 posts)
• Episode 4: DeepSeek V4.1 Flash Nears Frontier Models at a Fraction of the Cost, Independent Tests Show(2026-09-09, 15 posts)
• Episode 5: DeepSeek Releases Open-Source V4.1 Flash, Beating Its Own Flagship at a Fraction of the Cost(2026-09-09, 57 posts)
• Episode 6: DeepSeek V4.1 Flash Leaks: 552B Asymmetric MoE Claimed to Rival GPT-5.6 Sol(2026-09-10, 21 posts)
• Episode 7: DeepSeek V4.1 Flash Benchmark Results Leak, Sparking Community Discussion(2026-09-10, 2 posts)
• Episode 8: DeepSeek Shrinks Per-Token KV Cache 54x in Nine Months to Sub-KB Levels(2026-09-10, 6 posts)
• Episode 9: Leaked DeepSeek-V4.1-Flash Touted as New Open-Source King(2026-09-10, 3 posts)
• Episode 10: Bug Hunt Bench Ranks Frontier Coding Models on 105 Real Bugs(2026-09-10, 13 posts)
• Episode 11: DeepSeek V4.1 Flash Confirmed to Center on YOCO Architecture(2026-09-10, 7 posts)
• Episode 12: Leaked DeepSeek V4.1 Flash Tech Report Reveals KV Cache-Obsessed Flagship(2026-09-11, 44 posts)
• Episode 13: DeepSeek V4.1 Flash tops Vals open-source index at $0.30 per run(2026-09-11, 2 posts)
• Episode 14: DeepSeek launches V4.1-Flash: 552B backbone, 1M-token context(2026-09-11, 5 posts)
• Episode 15: DeepSeek V4.1 Flash scores 40 in AA index despite rising hallucinations(2026-09-11, 2 posts)
• Episode 16: Inside KV-Cache Sharing: How DeepSeek CED and GLM 5.2 Differ(2026-09-11, 4 posts)
• Episode 17: DeepSeek 4.1 Flash Shows Big Gains in Kernel Engineering and Cost(2026-09-11, 2 posts)
• Episode 18: SGLang delivers Day 0 support for DeepSeek V4.1 Flash, hitting 873 tok/s(2026-09-12, 2 posts)

• DeepSeek V4.1 Flash Vision Beta tested in 5 visual tasks: far better and cheaper than V4 — cheezeerd · 2026-09-09
• DeepSeek V4.1 Flash Vision Beta tested: big quality jump and lower API pricing — cheezeerd · 2026-09-09
• DeepSeek V4.1 Finds 65.6% of CVEs on Cybersecurity Bench, Matches Frontier Models at a Fraction of the Cost — teortaxesTex · 2026-09-09
• DeepSeek v4.1 Flash Hits 98% of Astra's Score at 1.4% of the Cost — uxl · 2026-09-09
• Blogger's test: DeepSeek V4.1 Flash scores 98% of GPT-6 Astra at 1.4% of the cost — solyarisoftware · 2026-09-10
• [source] 105 hidden bugs tested: DeepSeek V4.1 Flash near Opus 5 at 1/28th the cost — PawelHuryn · 2026-09-10
• DeepSeek V4.1-Flash beats V4-Pro on Terminal-Bench at 1/20th the cost of Opus 5 — dejavucoder · 2026-09-10
• DeepSeek-V4.1-Flash aces 22 knowledge-work tasks for just $0.34 in eval run — realsohamparekh · 2026-09-10
• Third-Party Benchmark Claims DeepSeek V4.1 Flash Matches 98% of GPT-6 at 1.4% of Cost — ChrisUniverse · 2026-09-10
• [source] Internal eval: DeepSeek V4.1 Flash nearly SOTA at 98% lower cost than Fable 5.1 — himanshustwts · 2026-09-11
• DeepSeek 4.1 Flash Hits 200 TPS Full Precision on 4 Max-Qs with Just 64GB RAM — TheZachMueller · 2026-09-11
• [source] DeepSeek V4.1 Flash scores 40 on Intelligence Index at 190 tokens/sec — ArtificialAnlys · 2026-09-11

3 near-duplicate retellings: PawelHuryn · soveLight · sanderjson