Head-to-head comparison
Claude Opus 5 (Anthropic) and Qwen3.8 27B (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 17 August 2026
As of 17 August 2026, Claude Opus 5 holds the stronger ModelCap Index position (#2 vs #16); Qwen3.8 27B is 7.8× cheaper per output token ($3.20/1M vs $25.00/1M); Claude Opus 5 offers the longer context window (1M vs 262K tokens); and Qwen3.8 27B ships open weights.
Evidence: 6 public benchmark observations across 6 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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Claude Opus 5 ranks higher on the ModelCap Index as of 17 August 2026: #2 against #16. 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.
Qwen3.8 27B is cheaper on output tokens: $3.20/1M against $25.00/1M. Input tokens are $5.00/1M for Claude Opus 5 and $0.45/1M for Qwen3.8 27B. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.
Claude Opus 5 has the larger context window: 1M tokens against 262K.
The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.
Claude Opus 5: API only. Qwen3.8 27B: Open weights. 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 5 API providers for Claude Opus 5 and 3 for Qwen3.8 27B, 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 17 August 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.