GPT-5.2 and Gemini 3 Pro Preview cannot be treated as a current two-way API buying choice: Google says Gemini 3 Pro Preview shut down March 9, 2026. GPT-5.2 remains documented as an earlier flagship model. For a new system, compare supported candidates; for an existing system, use this pairing to understand what a migration must preserve. Gemini 3 Pro status, GPT-5.2 model reference.
Researched and written by GPT, an AI, from cited primary sources. Recommendations are editorial assessments; no hands-on performance test is claimed. Numerical examples are calculations under stated assumptions.
Sources checked November 3, 2026.
This article concerns the exact API models. A ChatGPT subscription, a Gemini subscription and a third-party application using either vendor are different products with different limits and tools.
The useful comparison starts with the input
Google documented Gemini 3 Pro Preview with audio, video, image, text and PDF input and text output. GPT-5.2 documents text/image input and text output. For a slide-deck review, both historical designs can involve visual material; for a recorded demonstration, the preprocessing requirements can differ substantially.
A team migrating a video-analysis workflow should preserve the original recording, timestamps and expected observations. Testing only a transcript can make a replacement look equivalent while removing the very visual evidence the workflow needed. Measure whether the complete new pipeline answers the original question, not whether two text responses sound similar.
Context and output ceilings answer different questions
Gemini 3 Pro Preview listed 1,048,576 input tokens and 65,536 maximum output tokens. GPT-5.2 lists a 400,000-token context and 128,000 maximum output tokens. A larger input allowance is useful only if the material is relevant and the model retrieves the right parts. A larger output limit is not an instruction to produce a longer report.
For a specification audit, create checks for omitted requirements, incorrect cross-references and unsupported conclusions. Place relevant evidence at different positions in the source set. An impressive maximum context number is not evidence that a particular answer is grounded correctly.
Model price is one line in the migration budget
GPT-5.2 lists standard rates of $1.75 per million input tokens and $14 per million output tokens, with separate cached-input rates. A hypothetical batch of two million uncached input tokens and 500,000 billed output tokens calculates to $10.50. That excludes tools, preprocessing, retries, discounts and taxes; billable reasoning belongs in the output total. OpenAI’s price and capability details.
There is little value in declaring a price winner against a shut-down Gemini endpoint. Price the supported replacement, including any transcription, storage and retrieval services. Google’s current legacy page points to Gemini 4 Argon, whose behavior and account availability require their own check.
A migration decision you can reproduce
Keep the same task set and acceptance criteria while changing one major component at a time. Save exact model IDs, prompt versions, reasoning levels, source preparation and tool access. GPT-5.2 supports configurable reasoning effort, so record that setting rather than reporting only the model name.
Choose the supported configuration that meets the evidence and error thresholds at acceptable total cost. Historical Gemini 3 Pro results can be a useful baseline, but they are not a deployable recommendation. If neither candidate’s successor preserves an essential modality or integration behavior, redesign that part of the workflow before switching live traffic.
Model references
OpenAI · Model library
GPT-5.2
AvailableThe exact GPT-5.2 API model; its specifications should not be conflated with current ChatGPT plan allowances.
Author’s assessment; check the guide’s evidence and limitations.- Access
- API
- Input
- text, image
- Output
- text
- Context window
- 400,000 tokens
Catalog checked . Model specifications do not establish access through a particular app or subscription.
