Gemini 3 Flash Preview (Reasoning) vs o3: The Ultimate Performance & Pricing Comparison

Gemini 3 Flash Preview (Reasoning) is the stronger measured choice, while o3 is the safer speed choice only where its documented generation rate matters.

The supplied Artificial Analysis snapshot gives Gemini 3 Flash Preview (Reasoning) a 37.8 Intelligence Index and a 97 Math Index. o3 records 30.4 and 88.3 on the same measures. Data provided by https://artificialanalysis.ai/

The commercial gap also favors Gemini 3 Flash Preview (Reasoning). Its blended price is $1.1250000000000002 per 1M tokens, compared with $3.5 for o3. The input prices are $0.5 and $2, while output prices are $3 and $8. Data provided by https://artificialanalysis.ai/

The comparison has an important qualification: the names in the data snapshot do not map cleanly to current official product catalogs. Google lists Gemini 3 Flash as Preview with the API alias gemini-3-flash-preview, but the supplied official page does not document the “Reasoning” suffix. Gemini API model documentation OpenAI’s current model directory does not list o3 in the supplied page. OpenAI Models

Gemini 3 Flash Preview (Reasoning) wins the supplied comparison on measured quality and blended cost, but o3 has the only reported output-speed figure.

The main selection question is therefore not simply which model scores higher. It is whether the application can accept preview or catalog uncertainty in exchange for stronger measured results and lower listed cost.

Google’s official documentation presents Gemini 3 Flash as a Preview model intended to provide frontier performance at lower cost. Gemini API model documentation The same page does not provide the model’s context window, maximum output length, complete API parameters, or benchmark results. Gemini API model documentation

OpenAI’s supplied model documentation presents a current catalog centered on newer GPT-5.6 variants and does not list o3. OpenAI Models That omission does not prove that o3 cannot be called, but it does mean the supplied evidence cannot establish current availability, a stable alias, or an official replacement path.

Gemini 3 Flash Preview (Reasoning) has the stronger measured evaluation profile, while o3 has the only verified generation-speed figure in the supplied data.

The Intelligence Index gap is 37.8 versus 30.4, and the Math Index gap is 97 versus 88.3. Those differences suggest that Gemini 3 Flash Preview (Reasoning) is the better first candidate for workloads where broad task quality or mathematical reasoning drives acceptance. Data provided by https://artificialanalysis.ai/

The evidence does not identify which individual benchmark tasks created those aggregate scores. A developer should therefore treat the indices as screening evidence, not as a guarantee for code repair, tool use, structured extraction, or long multi-step workflows. The supplied materials contain no verified community tests for either model’s coding behavior, speed perception, or recurring failure modes.

The speed comparison is asymmetric. o3 reports 128.056 median output tokens per second. Gemini 3 Flash Preview (Reasoning) has no reported median output-token rate, so the data cannot establish that Gemini is slower, faster, or equivalent. Data provided by https://artificialanalysis.ai/

Latency does not resolve that uncertainty because both models show 0.3 seconds in the snapshot. That value says the recorded first-response timing is tied in this dataset. It does not describe total completion time, streaming smoothness, queue behavior, or performance under production concurrency.

For interactive products, o3 deserves a controlled latency and streaming trial because it has a concrete speed observation. For reasoning-heavy batch work, Gemini deserves the first quality trial because its measured indices are higher. The supplied sources do not establish a winner for coding, tool calling, multimodal input, context-heavy prompts, or output-limit-sensitive tasks.

Gemini 3 Flash Preview (Reasoning) is materially cheaper on every supplied token-price measure, but price alone cannot determine total application cost.

The blended price is $1.1250000000000002 for Gemini 3 Flash Preview (Reasoning) and $3.5 for o3 per 1M blended tokens. Input pricing is $0.5 versus $2, and output pricing is $3 versus $8. Data provided by https://artificialanalysis.ai/

The practical advantage depends on whether the model can complete the task in one useful response. A cheaper model may become more expensive at the application level if it needs retries, extra verification calls, larger prompts, or manual review. The supplied data does not measure any of those effects, so it cannot prove an end-to-end cost winner for a specific workflow.

Output-heavy applications should pay close attention to the output-price gap. A system that generates long explanations, code patches, or structured records may be more sensitive to output pricing than to input pricing. The data shows $3 for Gemini 3 Flash Preview (Reasoning) and $8 for o3 per 1M output tokens. Data provided by https://artificialanalysis.ai/

Prompt-heavy applications still favor Gemini on the listed input price, but the missing context-window and output-limit details matter. Google’s pricing page confirms that the Gemini API has free, paid, and enterprise tiers, yet it does not list a separate price for the exact gemini-3-flash-preview alias in the supplied material. Gemini API pricing

OpenAI’s supplied pricing page does not list o3 prices for Standard, Batch, Flex, or Fast mode. OpenAI API pricing This creates a crucial distinction: the data snapshot supplies comparison prices, while the current official pages do not independently confirm a live purchasing path for either exact comparison entry.

Gemini 3 Flash Preview (Reasoning) is the default pick for developers optimizing measured quality and token economics, while o3 fits a narrower speed-first evaluation path.

Choose Gemini 3 Flash Preview (Reasoning) for a new prototype when the application can tolerate Preview status and the first goal is to maximize quality per token. Its 37.8 Intelligence Index, 97 Math Index, and $1.1250000000000002 blended price make that choice compelling in the supplied snapshot. Data provided by https://artificialanalysis.ai/

Choose o3 for a targeted trial when interactive generation speed is a primary product requirement. It is the only model with a reported median output rate, at 128.056 median output tokens per second. That evidence is useful, but it does not show that o3 is currently available through a stable official endpoint. OpenAI’s supplied model directory does not list o3, and its pricing page does not list o3 pricing. OpenAI Models OpenAI API pricing

Use a two-stage evaluation before committing to production. First, test representative prompts for answer correctness, mathematical reliability, code changes, tool calls, and structured output. Second, measure retries, review time, total tokens, time to first token, full completion time, and failure recovery. The supplied research does not contain these measurements, so they must come from the developer’s own workload.

Do not make context-heavy architecture decisions from this comparison. Neither model has a verified context-window value in the supplied data. Google’s model page omits that detail for Gemini 3 Flash, while the supplied OpenAI model page does not provide it for o3. Gemini API model documentation OpenAI Models

The final recommendation is conditional rather than absolute: start with Gemini for quality and cost, retain o3 as a speed benchmark, and postpone a production commitment until availability and limits are verified directly in the intended API account.

Gemini 3 Flash Preview (Reasoning) should be the first model tested for quality-sensitive applications because its supplied evaluation results exceed o3 on both listed indices. Data provided by https://artificialanalysis.ai/