Head-to-head · 2026
Gemini 4 Argon vs GPT-5.5
Verdict. Gemini 4 Argon passed 5/5 tasks in Starlight Arena Round 6 against GPT-5.5’s 3/5 (2 partials on WCAG contrast and strict word-window cap), while costing 60–67% less per token. Keep GPT-5.5 where Codex-native terminal or OSWorld desktop loops are already qualified.
AI Architect Recommendation
For new multimodal and web-engineering pipelines, start with Gemini 4 Argon and verify cache hit rates in Langfuse. Migrate GPT-5.5 workloads only when re-running your own harness receipt confirms parity on your tool schemas.
AI CoE pillar: Technology · model routing + Governance · receipt-backed migration
- Web UI & TypeScript builders: Gemini 4 Argon (5/5 Round 6)
- Multimodal video/audio analysts: Gemini 4 Argon
- Codex CLI terminal agents: GPT-5.5
| Gemini 4 Argon | GPT-5.5 | |
|---|---|---|
| Provider | Google DeepMind | OpenAI |
| Released | 2026-10-08 | 2026-04-23 |
| Context | 1.05M | 1M |
| Max output | 66K | 128K |
| Input /1M | $2.00 | $5.00 |
| Output /1M | $10.00 | $30.00 |
| Modalities | text, vision, audio, video | text, vision, audio, video |
The analysis
Starlight Arena Round 6 tested both models on the same five mechanical tasks. Gemini 4 Argon passed all five (5/5) at $2.00/$10.00 per million tokens. GPT-5.5 passed three (TypeScript row joiner, provenance pushback, Langfuse adapter) and scored partial on two: its secondary muted badge text fell below the 4.5:1 WCAG AA contrast threshold on Task 2, and its Task 3 brief ran 9 words over the 265-word ceiling.
On unit economics, Argon’s $2/$10 ($0.10 cached input through 30 November 2026) undercuts GPT-5.5’s $5/$30 by 2.5x on input and 3x on output, while holding a full 1,048,576-token window across text, image, audio, video, and PDF.
GPT-5.5 retains its advantage inside OpenAI’s Codex CLI harness and customer-workflow automation where teams have already validated its tool-calling schemas.
Pick Gemini 4 Argon if…
- You need 1M native multimodal context (including video and audio) at $2/$10
- Strict formatting caps and WCAG-compliant UI component generation
- Warm-cache agentic loops ($0.10/1M cached input)
Pick GPT-5.5 if…
- Existing OpenAI Codex CLI and Responses API production pipelines
- OSWorld-style desktop automation already tuned to GPT-5.5
- Workloads paired with OpenAI’s realtime voice stack
Gemini 4 Argon
Google DeepMind’s October 2026 flagship — 1M native multimodal context and $2/$10 introductory pricing, with a published Round 6 Starlight Arena receipt.
GPT-5.5
OpenAI’s agentic flagship at its April 2026 launch: best-in-class computer-use and knowledge-work scores at the time, at double the price.