GPT-5.5 vs Gemini 3.1 Pro: Which Is Better for Coding? (2026)

head-to-head

Metric	GPT-5.5	Gemini 3.1 Pro
SWE-bench Verified	82.6%	80.6%
SWE-bench Pro	58.6%	54.2%
Terminal-Bench	82.7% (TB2.0)	—
Input $ / 1M	—	—
Context	—	—
Open weights	No	No
Maker	OpenAI	Google DeepMind

when to pick each

Pick GPT-5.5 if

OpenAI's strongest agentic coder, with the deepest tooling and ecosystem breadth of the closed labs.

Pick Gemini 3.1 Pro if

Google's strongest coding model today, with deep Workspace/Cloud integration. (A 3.5 Pro is expected but not shipped.)

Ranked on our AI Coding Leaderboard, updated 2026-07-02. Scores are confirmed against primary sources; prices are per 1M input tokens and can change.

Primary sources

OpenAIvals.ai — SWE-bench Verified (independent) — Verified score from vals.ai independent eval; Pro is OpenAI-reported (rivals flag possible memorization on Pro).
Google DeepMindGoogle DeepMind — Gemini Pro — DeepMind-reported pass rate; ties DeepSeek V4 on Verified, trails it on Pro.
BenchmarkSWE-bench — the real-GitHub-issue benchmark

$ quick-answers

Is GPT-5.5 better than Gemini 3.1 Pro for coding?

GPT-5.5 scores higher on SWE-bench Verified (82.6% vs 80.6%) and SWE-bench Pro, so it is the stronger coder on current benchmarks.

Which is cheaper, GPT-5.5 or Gemini 3.1 Pro?

Public per-token pricing isn't confirmed for both, so we don't print a price comparison yet.

Should I use GPT-5.5 or Gemini 3.1 Pro?

GPT-5.5 for the hardest, highest-stakes coding; Gemini 3.1 Pro when you want the best value or are running high volume. Both are frontier-class in 2026.