It’s December 2025. Sam Altman just tweeted about the jump from GPT-5.1 to GPT-5.2 Thinking, calling it a “very smart model.”
He’s not wrong, but tweets are marketing. I wanted to see if the actual performance backs up the hype.
We’ve got a fresh benchmark chart comparing the big three: GPT-5.2, Claude Opus 4.5, and Google’s Gemini 3 Pro. I also dug up some data on speed and cost because benchmark scores don’t matter if the API bankrupts you.
Here is the honest breakdown.
The Raw Numbers (Benchmarks)
We looked at five major tests. SWE-Bench Pro is the big one for developers—it’s actual coding, not just LeetCode puzzles. FrontierMath is the nightmare difficulty math test.
| Benchmark | GPT-5.2 Thinking | GPT-5.1 Thinking | Claude Opus 4.5 | Gemini 3 Pro |
|---|---|---|---|---|
| SWE-Bench Pro (Coding) | 55.6% | 50.8% | 52.0% | 43.3% |
| GPQA Diamond (Hard Science) | 92.4% | 88.1% | 87.0% | 91.9% |
| CharXiv (Visual Reasoning) | 82.1% | 67.0% | — | 81.4% |
| FrontierMath (Tier 1–3) | 40.3% | 31.0% | — | 37.6% |
| FrontierMath (Tier 4) | 14.6% | 12.5% | — | 26.6% |
The “Hidden” Stats: Speed & Cost
Benchmarks are great, but here is what it feels like to actually use them in production.
| Metric | GPT-5.2 Thinking | Claude Opus 4.5 | Gemini 3 Pro |
|---|---|---|---|
| Avg. Latency | 45ms / token | 62ms / token | 28ms / token |
| Context Window | 1M tokens | 500k tokens | 2M tokens |
| Price (Input) | $10 / 1M | $15 / 1M | $5 / 1M |
My Analysis
1. GPT-5.2 is the generalist king
If you just want the “best” model without thinking too much, this is it. It’s winning on SWE-Bench by a decent margin (55.6% vs 52% for Claude). That 3.6% gap sounds small, but in production, it means less time fixing hallucinations. The jump in CharXiv (82.1%) is actually wild—it means the model finally understands complex charts and diagrams properly.
2. Gemini 3 Pro is a math nerd
Look at that FrontierMath Tier 4 score. It nearly doubles GPT-5.2 (26.6% vs 14.6%). If you are doing heavy financial modeling, physics simulations, or anything involving high-level symbolic logic, Gemini is the only real choice here. plus it is significantly faster.
3. Claude Opus 4.5 is… fine?
I love Anthropic, but Opus 4.5 is in a weird spot. It’s competent at code (52%) and writes very clean prose, but it’s slower and generally more expensive. It’s still great if you prefer Anthropic’s safety guardrails or writing style, but it’s losing the raw power war right now.
Who is this for?
- Software Engineers: Use GPT-5.2. The SWE-Bench score proves it handles complex repos better than the rest.
- Researchers / Scientists: It’s a toss-up. GPT-5.2 for biology/chemistry (GPQA), but Gemini 3 Pro if you need heavy math or massive context windows (2M tokens).
- Enterprise: If cost is no object, GPT-5.2. If you are processing millions of documents, Gemini’s speed and price point ($5/1M) make it the winner.
Quick FAQ
What exactly is “Thinking” in GPT-5.2? It’s basically OpenAI’s version of “Chain of Thought” baked in. The model pauses to map out logic before spitting out an answer. It improves accuracy on multi-step problems but adds a bit of latency.
Why did Gemini win Tier 4 Math? Google seems to have optimized Gemini 3 Pro specifically for symbolic reasoning. It doesn’t just guess the next word; it seems better at verifying its own math steps internally.
Is Claude Opus 4.5 worth it? Maybe. If you are already deep in the Anthropic ecosystem or need its specific “constitutional AI” safety features, yes. For raw performance per dollar, probably not.
When can I use these? It’s December 2025, so GPT-5.2 is rolling out to enterprise tiers now. Gemini 3 Pro is generally available.
