Compare DeepSeek V3.1 Fast from DeepSeek and DeepSeek V4 Flash from DeepSeek on key metrics including benchmarks, price, context length, and other model features. Access both models and hundreds of others through the AIHubMix API.
DeepSeek V3.1 FastDeepSeek V4 FlashThe model provider is the Sophon platform. DeepSeek V3.1 Fast is the high-TPS speed version of DeepSeek V3.1. Hybrid thinking mode: By modifying the chat template, a single model can simultaneously support both thinking and non-thinking modes. Smarter tool usage: Through post-training optimization, the model’s performance in tool utilization and agent tasks has improved significantly.
(This model currently points to the older 0423 version; if you need to request the latest version, you can choose the model deepseek-v4-flash-0731)DeepSeek-V4 features an ultra-long context of one million characters and achieves leading performance domestically and in the open-source domain in agent capabilities, world knowledge, and reasoning.
Prices are per million tokens. Time to First Token and throughput are rolling averages measured on AIHubMix.
Promotional prices show the discounted rate; see each model page for promotion windows.
Daily traffic served through AIHubMix — how demand for each model is trending.
Measured on real AIHubMix traffic, hourly buckets. Gaps mean no traffic in that hour.
Estimate your monthly bill for the same workload on each model.
Monthly = daily × 30. Discounted rates applied where a promotion is active.
DeepSeek V4 Flash: $0.284/M output tokens; DeepSeek V3.1 Fast: $3.288/M. Use the cost calculator above to estimate your own workload.
DeepSeek V3.1 Fast: 0.2s time to first token measured on AIHubMix; see the live performance charts above for how each model behaves across the day.
DeepSeek V3.1 Fast accepts 163,000 and DeepSeek V4 Flash accepts 1,000,000 input tokens. Maximum output per request is 163,000 tokens on DeepSeek V3.1 Fast and 384,000 tokens on DeepSeek V4 Flash.
DeepSeek V3.1 Fast at 150.0 tok/s and DeepSeek V4 Flash at 66.5 tok/s, measured as output throughput on AIHubMix — a separate metric from time to first token.
DeepSeek V3.1 Fast accepts text input and supports tool calling, function calling and structured outputs; DeepSeek V4 Flash accepts text input and supports tool calling, function calling, structured outputs and thinking.
Yes. AIHubMix serves every model on this page behind one OpenAI-compatible endpoint, so switching between them is a one-line change to the model field — no second account, key or SDK.
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