Claude Opus 4.6 vs Gemini 3.8 Flash

Wins 1 of 5 benchmarks

$0.93 / task

Wins 2 of 5 benchmarks

Different efforts: high · medium · Compare all at high

Only shared

Humanity's Last Exam Humanity's Last Exam: Very hard expert questions across many fields, written to stump today’s models

Opus 4.619.1

Gemini 3.8 Flash42.1

Terminal-Bench 4.0 Terminal-Bench 4.0 · source setting 2: Agents use a terminal to complete executable coding, system administration and research tasks in the 4.0 suite

Opus 4.6—

Gemini 3.8 Flash19.7

AutomationBench-AA AutomationBench-AA: Agents orchestrate SaaS workflows through APIs; objectives receive credit only when the task has no guardrail violation

Opus 4.6—

Gemini 3.8 Flash60.9

Arena Text · creative writing Arena Text · creative writing: Human pairwise preferences in the stated text vote pool

Opus 4.61,500

Gemini 3.8 Flash · high1,487

MMMU-Pro (vision) MMMU-Pro (vision): College-level questions that require understanding images: charts, diagrams, photos

Opus 4.672.5

Gemini 3.8 Flash84.2

Benchmark	Opus 4.6	Gemini 3.8 Flash
Humanity's Last Exam	19.1	42.1
Terminal-Bench 4.0	—	19.7
AutomationBench-AA	—	60.9
Arena Text · creative writing	1,500	1,487 · high
MMMU-Pro (vision)	72.5	84.2

Specs

Spec	Opus 4.6	Gemini 3.8 Flash
Input, per 1M	$5	!$0.75
Output, per 1M	$25	!$3.75
Cost per task?	—	$0.93
Speed, tok/s	45	—
Context	1M	1M
Weights	Closed	Closed
Released	Feb 2026	Sep 2026
See images	✓	✓
Read PDFs	Partial	✓
Hear audio	—	✓
Watch video	—	✓
Call tools	✓	✓
Force a tool call	Partial	Partial
Return strict JSON	✓	✓
Search the web	?	✓
Run code	?	✓
Use a computer	?	?

What breaks when you switch

Opus 4.6 → Gemini 3.8 Flash

Sampling parameters are ignored›

temperature, top_p and top_k are ignored now and will cause HTTP 400 in future generations; remove them from requests.

No minimal thinking level›

The minimal thinking level returns an error; avoid minimal.

Gemini 3.8 Flash → Opus 4.6

Nothing known.