DeepSeek V4 Flash 0731 (Reasoning, Max Effort) vs o3: The Ultimate Performance & Pricing Comparison

DeepSeek V4 Flash 0731 is the stronger default for most cost-sensitive developer workloads, while o3 remains relevant for math-heavy tasks. The measured intelligence index favors DeepSeek V4 Flash 0731 at 49.9 versus 30.4 for o3. The available math index favors o3 at 88.3, but the supplied data does not provide a matching DeepSeek mathematics score. The available coding index is 69.1 for DeepSeek V4 Flash 0731, with no comparable o3 value. That asymmetry matters: the evidence supports a broad advantage for DeepSeek on the supplied intelligence measure, but it does not establish a complete coding or mathematical ranking. Data provided by Artificial Analysis.

DeepSeek V4 Flash 0731 offers the clearest production case because its measured intelligence result is higher, its blended price is lower, and its official API status is documented. The model costs $0.175 per 1M blended tokens, compared with $3.5 for o3. That price gap changes architecture decisions: developers can afford more retries, longer reasoning traces, and broader automated evaluation before inference cost becomes the dominant constraint. The trade-off is output speed. o3 produces 128.056 median output tokens per second, compared with 102.212 for DeepSeek V4 Flash 0731, while both show 0.3 seconds of latency in the supplied comparison. DeepSeek also has a documented stable alias, current pricing page, thinking controls, tool calls, JSON Output, and Responses API support in the supplied official material. See DeepSeek Models & Pricing, Using the Responses API, and Thinking Mode. By contrast, the supplied OpenAI model documentation does not list o3 in the current model catalog, and the supplied pricing page does not show a current o3 price. See OpenAI Models and OpenAI API Pricing.

o3 is faster at generating tokens, but DeepSeek V4 Flash 0731 may be more efficient for workflows where reasoning depth and iteration matter more than raw streaming speed. The supplied measurements put o3 at 128.056 median output tokens per second and DeepSeek V4 Flash 0731 at 102.212. Both models show 0.3 seconds of latency, so the practical difference is more likely to appear during sustained generation than at request start. A faster stream helps interactive coding assistants, especially when users watch output continuously. It does not automatically mean a faster completed task. A cheaper model can support additional attempts, validation passes, or tool calls within the same budget. DeepSeek's coding index is 69.1, but the supplied data has no comparable o3 coding value, so developers should not describe DeepSeek as the definitive coding winner. The model's official documentation supports thinking modes and tool calls, while tool-call continuations require the complete reasoning content to be returned. That requirement can affect orchestration reliability if an SDK or middleware layer drops hidden reasoning fields. The relevant constraint is documented in Thinking Mode. Community reports also describe successful debugging of an unfinished website, but the report did not disclose a reproducible protocol, so it is useful as a scenario signal rather than a benchmark. See Deepseek v4 flash 0731 real experience.

DeepSeek V4 Flash 0731 is dramatically cheaper on the supplied pricing comparison, but its advantage depends on whether the application can exploit lower inference cost without adding wasteful calls. The blended price is $0.175 per 1M tokens for DeepSeek V4 Flash 0731 versus $3.5 for o3. Input pricing is $0.14 for DeepSeek V4 Flash 0731 versus $2 for o3, while output pricing is $0.28 versus $8. Output-heavy agents therefore face a particularly large cost penalty with o3. The meaningful question is not simply which model has the lower unit price. A model becomes more expensive in practice if it needs repeated corrections, produces unusable tool arguments, or requires a second model for routine validation. The supplied material does not provide a standardized failure rate, task-completion cost, or comparable production trace for either model, so that break-even point remains unproven. DeepSeek's official page documents cache-hit input pricing at $0.0028 and warns that peak pricing may become twice the regular price when the announced change takes effect. The same page lists an account-level concurrency limit of 2,500, with excess requests returning HTTP 429. Those operational conditions belong in a capacity model alongside token price. See DeepSeek Models & Pricing and Rate Limit & Isolation.

DeepSeek V4 Flash 0731 should be the first choice for general developer agents, code maintenance, and budget-sensitive production systems. Its available intelligence score is 49.9, its coding score is 69.1, and its blended price is $0.175 per 1M tokens. The official material also gives developers a concrete integration path through a stable model alias, thinking controls, tool calls, JSON Output, and a Responses API. These facts make it easier to design a service around known interfaces and known billing, although production teams still need to test their own prompts and tools. Using the Responses API confirms the supplied Responses API path, while DeepSeek Models & Pricing covers the model and pricing details. Choose o3 when mathematical reasoning is the deciding capability and the available math index of 88.3 matches your evaluation target. That recommendation is narrower because the supplied official sources do not establish current o3 availability, a stable alias, current API parameters, context limits, or current pricing. OpenAI Models does not list o3 in the supplied current catalog, and OpenAI API Pricing does not provide an o3 price in the supplied material. Do not select either model solely from community anecdotes. DeepSeek reports include useful coding and deployment observations, but they lack standardized test protocols. A local deployment report records 12.5 tokens per second on a specific RTX 3090 setup, and it also explains that memory placement affects speed. See DeepSeek-V4-Flash-0731 UD-IQ3_S 12.5 tok/s.

DeepSeek V4 Flash 0731 has stronger documented evidence for current API use, but the supplied sources do not prove which model completes every developer task more reliably. The comparison contains a measured intelligence advantage for DeepSeek V4 Flash 0731 and a measured math advantage for o3, yet those indexes cover different evidence areas. It also contains no comparable o3 coding score, no standardized task-completion study, and no verified production error-rate comparison. The version-status evidence is asymmetric as well. DeepSeek's current model and pricing page explicitly presents DeepSeek-V4-Flash-0731 and its stable alias, while the supplied OpenAI model page does not list o3. That absence is important for procurement, but it does not by itself prove that every o3 endpoint is unavailable. Developers should treat availability, billing, and migration risk as questions requiring a direct account-level check. OpenAI Models is the relevant source for current model visibility. For DeepSeek operational behavior, Rate Limit & Isolation documents the concurrency and connection rules. The evidence supports a practical default, not a universal capability verdict.