DeepSeek V4 Flash Cost Breakdown: Cache Hit Rate and Price Ratio Explained

A Reddit user analyzed 922 agentic task traces running on OpenClaw (with PI agent loop) and OpenRouter, comparing DeepSeek V4 Flash against Opus 4.7. The cost difference is staggering: $0.01 per task for DeepSeek vs $1.52 for Opus, despite similar token counts (~962K avg) and tool calls (~14 avg). The price ratio is 0.0066x, far below the expected 0.03x based on input token pricing alone.

Why DeepSeek is cheaper: Cache hit rate and read/write price

Two factors account for the gap:

• Cache hit rate: DeepSeek V4 Flash achieved 97% vs Opus 4.7's 87%. At these cache read-write price ratios, each 1% higher cache hit yields ~20% lower overall cost. DeepSeek's 10% advantage cuts about 2/3 of total cost.
• Cache read-write price ratio: DeepSeek's ratio is 0.02 (cache read costs 2% of a cache miss write), while Opus sits at 0.08 — comparable to OpenAI, Anthropic, and Gemini (0.08–0.10). This alone halves the cost further.

How it adds up

With similar tokens and tools per task, DeepSeek's total cost is 0.0066x that of Opus. The user speculates that these efficiencies are engineered at the infrastructure or model architecture level (e.g., better caching strategy). The exact mechanism is not disclosed.