Gemini 3.1 Pro Preview vs GPT-5.2
Gemini 3.1 Pro Preview and GPT-5.2 are both frontier-tier models released within two months of each other (Feb 2026 vs Dec 2025) and both run on OpenKey with one key plus a flat 3% fee on provider list price. They split on architecture: Gemini keeps reasoning always-on with three effort tiers, GPT-5.2 makes reasoning optional with five tiers including a no-reasoning fast path. Context and pricing structure diverge enough that the right choice depends heavily on your input/output mix.
Spec vs spec
| Spec | Gemini 3.1 Pro Preview | GPT-5.2 |
|---|---|---|
| Context window | 1.0M | 400K |
| Max output | 66K | 128K |
| Input modalities | audio, file, image, text, video | file, image, text |
| Output modalities | text | text |
| Released | Feb 19, 2026 | Dec 10, 2025 |
| Reasoning | always on | optional |
Pricing
Per 1M tokens. Provider price plus the flat 3% fee — the sum is what you pay.
google/gemini-3.1-pro-preview
Input · 1M tokens
$2.00 + 3%$2.06
Output · 1M tokens
$12.00 + 3%$12.36
Cache read · 1M tokens
$0.200 + 3%$0.206
Cache write · 1M tokens
$0.375 + 3%$0.386
FEE — FLAT, EVERY MODEL3%
openai/gpt-5.2
Input · 1M tokens
$1.75 + 3%$1.80
Output · 1M tokens
$14.00 + 3%$14.42
Cache read · 1M tokens
$0.175 + 3%$0.180
FEE — FLAT, EVERY MODEL3%
One workload, priced on both
10M input + 2M output tokens at each model's price, flat 3% fee included.
google/gemini-3.1-pro-previewCheaper
$45.32
$44.00 provider + 3%
openai/gpt-5.2
$46.87
$45.50 provider + 3%
Benchmarks
Design Arena categories where both models have results. Higher Elo and lower rank win.
| Gemini 3.1 Pro Preview | GPT-5.2 | |||
|---|---|---|---|---|
| Category | Elo | Rank | Elo | Rank |
| 3D | 1303 | #17 | 1156 | #60 |
| androidnative | 1059 | #25 | 1074 | #22 |
| ASCII art | 1314 | #4 | 1199 | #22 |
| Code | 1290 | #18 | 1219 | #42 |
| Data viz | 1270 | #20 | 1245 | #31 |
| Full-stack | 1139 | #16 | 1110 | #21 |
| Game dev | 1264 | #26 | 1260 | #29 |
| godotgamedev | 1220 | #6 | 1183 | #13 |
| Mobile apps | 1176 | #22 | 1173 | #23 |
| SVG | 1347 | #2 | 1197 | #31 |
| UI components | 1322 | #8 | 1243 | #32 |
| Web apps | 1196 | #13 | 1156 | #19 |
| Websites | 1294 | #15 | 1237 | #34 |
Head-to-head preference voting. How we filter and rank
Pricing math on a real workload
Provider list price: Gemini charges $2.00/M input and $12.00/M output. GPT-5.2 charges $1.75/M input and $14.00/M output. On OpenKey, add the flat 3% fee: Gemini becomes $2.06/M input and $12.36/M output; GPT-5.2 becomes $1.8025/M input and $14.42/M output. Gemini's input rate is 1.14x GPT-5.2's — GPT-5.2 is actually cheaper per input token. But GPT-5.2's completion price is high enough to flip the total on output-heavy work: for 10M input tokens plus 2M output tokens, Gemini comes out to $44.00 total versus GPT-5.2's $45.50. The gap is small at this ratio, but it widens fast as output share grows, since GPT-5.2's completion rate is $14.00/M provider list against Gemini's $12.00/M.
Context and output limits
Gemini 3.1 Pro Preview supports 1,048,576 tokens of context, 2.62x GPT-5.2's 400,000. If you're feeding in large codebases, long transcripts, or multi-document RAG contexts, Gemini has real headroom GPT-5.2 doesn't. GPT-5.2 flips the advantage on the output side: 128,000 max completion tokens versus Gemini's 65,536, useful for long-form generation, large diffs, or extended agent traces in a single response. Neither number is a benchmark — it's a hard ceiling, so pick based on which side of the input/output equation your workload actually stresses.
Modality differences
Gemini 3.1 Pro Preview accepts text, image, file, audio, and video as input. GPT-5.2 accepts text, image, and file — no native audio or video input. If your pipeline needs to process audio transcripts or video frames directly rather than pre-converting them to text, Gemini is the only one of the two that handles it natively. Both output text only.
Reasoning control
Gemini 3.1 Pro Preview's reasoning is mandatory, with three effort levels (low, medium, high) and medium as default — you can tune depth but can't turn it off. GPT-5.2 supports five levels (none, low, medium, high, xhigh), also defaulting to medium, and 'none' gives you a fast, non-reasoning path for latency-sensitive calls. If your application needs to dial down to near-zero reasoning overhead for simple requests, GPT-5.2's range gives you that option; Gemini doesn't.
Which model for which job
| Use case | Pick | Why |
|---|---|---|
| Long-document analysis (100K+ tokens) | Gemini 3.1 Pro Preview | 1,048,576 token context is 2.62x GPT-5.2's 400,000 |
| Output-heavy generation (long reports, big diffs) | Gemini 3.1 Pro Preview | Completion price is $12.36/M on OpenKey vs GPT-5.2's $14.42/M |
| Single very long response in one call | GPT-5.2 | 128,000 max completion tokens vs Gemini's 65,536 |
| Audio or video input processing | Gemini 3.1 Pro Preview | Only model of the two with native audio and video input modalities |
| Latency-sensitive, low-reasoning calls | GPT-5.2 | Supports a 'none' reasoning effort level; Gemini's reasoning is mandatory |
| Input-heavy, short-response workloads | GPT-5.2 | Input price is $1.8025/M on OpenKey vs Gemini's $2.06/M |
Questions
- Which model is cheaper overall?
- It depends on your input/output mix. GPT-5.2 has the cheaper input rate ($1.8025/M vs $2.06/M on OpenKey), but Gemini 3.1 Pro Preview has the cheaper completion rate ($12.36/M vs $14.42/M). On a 10M-input/2M-output workload, Gemini totals $44.00 versus GPT-5.2's $45.50.
- Which has the larger context window?
- Gemini 3.1 Pro Preview, by a wide margin — 1,048,576 tokens versus GPT-5.2's 400,000, a 2.62x ratio. If your use case involves feeding in large codebases or long documents, this matters more than per-token pricing differences.
- Can GPT-5.2 process audio or video?
- No. GPT-5.2's input modalities are limited to text, image, and file. Gemini 3.1 Pro Preview adds audio and video input on top of those, making it the only choice between the two for direct audio/video processing.
- Does either model let me disable reasoning for speed?
- GPT-5.2 does — it supports a 'none' effort level alongside low, medium, high, and xhigh. Gemini 3.1 Pro Preview's reasoning is mandatory, with only low, medium, and high as options, medium being the default for both models.