Head-to-head comparison
DeepSeek V4 Flash 0731 (DeepSeek) and Qwen3.8 Flash (Qwen) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.
Snapshot as of 10 September 2026
As of 10 September 2026, Qwen3.8 Flash holds the stronger ModelCap Index position (#14 vs #25); DeepSeek V4 Flash 0731 is 2.6× cheaper per output token ($0.18/1M vs $0.47/1M); DeepSeek V4 Flash 0731 offers the longer context window (1.3M vs 1M tokens); and DeepSeek V4 Flash 0731 ships open weights.
Evidence: 2 public benchmark observations across 2 boards · 1 public benchmark observation across 1 board. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.
Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.
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Qwen3.8 Flash ranks higher on the ModelCap Index as of 10 September 2026: #14 against #25. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.
DeepSeek V4 Flash 0731 is cheaper on output tokens: $0.18/1M against $0.47/1M. Input tokens are $0.065/1M for DeepSeek V4 Flash 0731 and $0.15/1M for Qwen3.8 Flash. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $0.22 for DeepSeek V4 Flash 0731 versus $0.53 for Qwen3.8 Flash. DeepSeek V4 Flash 0731 costs 58.9% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.
DeepSeek V4 Flash 0731 has the larger context window: 1.3M tokens against 1M.
AA Terminal-Bench 2.1: DeepSeek V4 Flash 0731 78.7%, Qwen3.8 Flash 86.1% — Qwen3.8 Flash leads.
DeepSeek V4 Flash 0731: Open weights. Qwen3.8 Flash: Restricted license. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.
ModelCap currently lists 28 API providers for DeepSeek V4 Flash 0731 and 2 for Qwen3.8 Flash, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.
Every figure comes from the sealed ModelCap dataset published 10 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.