GPT-5.5 vs Gemini 3.1 Ultra
The two flagship models of spring 2026, side by side — benchmarks, pricing, context window, and a plain answer to which one you should reach for.
GPT-5.5 vs Gemini 3.1 Ultra: side-by-side
| GPT-5.5 "Spud" | Gemini 3.1 Ultra | |
|---|---|---|
| Maker | OpenAI | |
| Released | 23 April 2026 | April 2026 |
| Context window | 1M tokens (400K in Codex CLI) | 2M tokens |
| Modalities | Text, image, audio, video | Text, image, audio, video (native, no transcription) |
| Built for | Agentic coding, computer use, deep research | Multimodal understanding, long documents |
| API price (per 1M) | $5 in / $30 out | ~$2 in / $12 out (Pro tier) |
| Code execution | Via Codex environment | Native sandboxed Python |
| Access | ChatGPT & Codex — paid tiers | Gemini app & API · $19.99/mo consumer |
Benchmark comparison
On head-to-head coding benchmarks, GPT-5.5 holds a consistent lead — widest on agentic, command-line style tasks.
| Benchmark | GPT-5.5 | Gemini 3.1 | Winner |
|---|---|---|---|
| SWE-bench Pro | 58.6% | 54.2% | GPT-5.5 |
| Terminal-Bench 2.0 | 82.7% | 68.5% | GPT-5.5 |
| Context window | 1M tokens | 2M tokens | Gemini 3.1 |
| Price per 1M output | $30 | ~$12 | Gemini 3.1 |
Key takeaway
GPT-5.5 wins capability on coding; Gemini 3.1 wins on context size and cost. The gap on Terminal-Bench 2.0 (14 points) is the most decisive single result — agentic, multi-step tool use is GPT-5.5's clearest advantage.
Where GPT-5.5 wins
If your work is code and computer-driven tasks, GPT-5.5 is the safer pick. OpenAI built this release around agentic reliability — chaining many steps together without drifting — and integrated it tightly into Codex for developers. It outperforms Gemini on every major coding benchmark, with the biggest margin on complex, multi-file tasks that resemble real engineering work.
Where Gemini 3.1 wins
If you work with video, audio or mixed media, Gemini 3.1 Ultra has a structural advantage: it reasons over those formats directly instead of transcribing them to text first. Less context is lost, which matters for analysis, captioning and media-heavy workflows. It also has double the context window (2M vs 1M tokens) and runs roughly 2.5x cheaper per token — so for high-volume jobs or whole-document reasoning, Gemini is the economical choice.
Price comparison
The cost gap is large enough to drive architecture decisions. Processing one million input and one million output tokens costs $35 on GPT-5.5 versus roughly $14 on Gemini 3.1 Pro. Over a high-volume production workload that 2.5x difference compounds quickly — which is why many teams route bulk traffic to Gemini and reserve GPT-5.5 for the hardest tasks.
Which should you use?
- Developers and automation builders → GPT-5.5 — best agentic coding, tightest Codex integration.
- Media, research and multimodal analysis → Gemini 3.1 Ultra — native video/audio, 2M context.
- High-volume or cost-sensitive workloads → Gemini 3.1 Pro — about 2.5x cheaper per token.
- Self-hosting or strict cost control → consider DeepSeek V4 — open MIT weights, from $0.14 per 1M tokens.
For most teams the smartest play is not a binary choice: use Gemini 3.1 as the workhorse for high-volume and media-heavy tasks, and bring in GPT-5.5 where the quality margin actually matters.
Full GPT-5.5 overview Full Gemini 3.1 overview
Frequently asked questions
Is GPT-5.5 better than Gemini 3.1 Ultra?
GPT-5.5 is better for agentic coding — it leads on every major coding benchmark, including 58.6% vs 54.2% on SWE-bench Pro and 82.7% vs 68.5% on Terminal-Bench 2.0. Gemini 3.1 Ultra is better for multimodal work and very long documents, with a 2M-token context window and native video/audio processing, at a lower price per token.
Which has a bigger context window?
Gemini 3.1 has the bigger context window: 2 million tokens versus GPT-5.5's 1 million tokens (400,000 in the Codex CLI).
Which model is cheaper?
Gemini 3.1 is cheaper. Gemini 3.1 Pro costs about $2 per million input tokens and $12 per million output tokens, versus $5 and $30 for GPT-5.5 — roughly a 2.5x difference in Gemini's favour.
Which is better for coding?
GPT-5.5 is better for coding. It outperforms Gemini 3.1 on every major coding benchmark and is integrated directly into the Codex environment for agentic, multi-file engineering work.
Which should I use for video and audio?
Use Gemini 3.1 Ultra. It processes video, audio and text together natively with no transcription step, preserving tone, timing and visual context — a structural advantage for media-heavy work.