Claude Opus 4.6 vs Gemini 3.1 Pro Preview

Pricing math on a real workload

On OpenKey, Claude Opus 4.6 costs $5.15/M input and $25.75/M output (provider price $5.00/$25.00 × 1.03 fee). Gemini 3.1 Pro Preview costs $2.06/M input and $12.36/M output (provider $2.00/$12.00 × 1.03). Run the same 10M-input / 2M-output job on provider list pricing and Opus 4.6 comes to $100.00 versus Gemini's $44.00 — Gemini is less than half the cost. That gap holds at any volume since it's driven by a 2.5x input price ratio between the two models. If your pipeline is token-heavy and quality-tolerant, that difference compounds fast across a month of agent runs.

Agentic coding performance

On Design Arena's agents categories, Opus 4.6 ranks in the single digits everywhere tested: fullstack (rank 4, 1288 elo, 68.6% win rate), mobileapps (rank 3, 1261 elo, 60.5%), webapps (rank 4, 1266 elo, 60.9%), and androidnative (rank 11, 1216 elo, 68.8%). Gemini 3.1 Pro Preview trails on the same categories — fullstack rank 16 (1139 elo, 45%), mobileapps rank 22 (1176 elo, 46.6%), webapps rank 13 (1196 elo, 48.2%), androidnative rank 25 (1059 elo, 39.2%) — but covers agentic slide and game-dev categories Opus 4.6 wasn't scored on, where it lands rank 5–8. Gemini also posts an Artificial Analysis coding index of 68.8 and agentic index of 21.4, numbers with no Opus 4.6 equivalent in this dataset to compare against.

Reasoning control and cost tuning

This is the real architectural difference. Gemini 3.1 Pro Preview makes reasoning mandatory — you pick from high, medium, or low effort, but you can't turn it off, and it defaults to medium. Claude Opus 4.6 makes reasoning optional and gives you four effort levels — max, high, medium, low — also defaulting to medium. That optionality matters operationally: for simple, low-stakes calls you can run Opus 4.6 with no reasoning overhead at all, a lever Gemini doesn't expose. If your workload mixes trivial lookups with hard agent tasks, Opus 4.6's on/off switch gives you a cost knob Gemini can't match.

Context, output limits, and modality

Context windows are close — Opus 4.6 at 1,000,000 tokens versus Gemini at 1,048,576, a ratio of 0.95, effectively a wash for long-document work. Max output diverges more: Opus 4.6 caps at 128,000 tokens, double Gemini's 65,536, which matters if you're generating long code files or reports in a single pass. Modality is the other split: Opus 4.6 accepts text, image, and file input; Gemini adds audio and video on top of those three. If your pipeline needs to process video or audio input directly, Gemini is the only option of the two.

Questions

Which model is cheaper to run at scale?

Gemini 3.1 Pro Preview. On a 10M-input/2M-output workload it costs $44.00 on provider list pricing versus $100.00 for Claude Opus 4.6 — a 2.5x gap driven by input price alone ($2.00/M vs $5.00/M). On OpenKey add the flat 3% fee to both: $2.06/$12.36 per M for Gemini, $5.15/$25.75 per M for Opus 4.6.

Can I turn off reasoning to save cost?

Only with Claude Opus 4.6. It supports four reasoning efforts (max, high, medium, low) and reasoning itself is optional, defaulting to medium. Gemini 3.1 Pro Preview's reasoning is mandatory — you choose among high, medium, or low, but there's no off switch.

Which model wins on agentic coding benchmarks?

Claude Opus 4.6, on every agents category where both were tested: fullstack (rank 4 vs rank 16), mobileapps (rank 3 vs rank 22), webapps (rank 4 vs rank 13), and androidnative (rank 11 vs rank 25) on Design Arena.

Do both models support the same input types?

No. Both accept text, image, and file input, but Gemini 3.1 Pro Preview also accepts audio and video — Opus 4.6 doesn't. Context windows are nearly identical (1,000,000 vs 1,048,576 tokens, a 0.95 ratio), but Opus 4.6's max output is 128,000 tokens versus Gemini's 65,536.