Claude Opus 4.8 vs Gemini 3 Flash Preview: price, scores, context

Side-by-side comparison

Criterion	Claude Opus 4.8	Gemini 3 Flash Preview
Developer	Anthropic	Google DeepMind
Released	May 28, 2026	December 17, 2025
Capability index	83.4 / 100	80.3 / 100
Input price	$5	$0.50
Output price	$25	$3
Cost of a typical task	$0.15	$0.016
Context window	1,000,000 tokens	1,048,576 tokens
Maximum output	128,000 tokens	65,536 tokens
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Accepted inputs	text, image, PDF	text, image, video, audio, PDF
Open weights	No	No
Knowledge cutoff	January 2026	January 2025

Two models head to head

This comparison pits two mid-range models, balancing quality and cost against each other: Claude Opus 4.8 and Gemini 3 Flash Preview, one from Anthropic, the other from Google DeepMind. The first dates from May 28, 2026, the second from December 17, 2025.

All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.

Which one is more capable?

On our capability index, Claude Opus 4.8 scores 83.4 out of 100 and Gemini 3 Flash Preview 80.3. Claude Opus 4.8 leads by 3.1 points.

On the 3 benchmarks reported for both, Claude Opus 4.8 wins 3 times and Gemini 3 Flash Preview 0:

GPQA Diamond (PhD-level science questions): Claude Opus 4.8 91%, Gemini 3 Flash Preview 89.4%
OTIS Mock AIME (competition mathematics problems): Claude Opus 4.8 98.3%, Gemini 3 Flash Preview 95.6%
FrontierMath (very hard research-level mathematics): Claude Opus 4.8 80%, Gemini 3 Flash Preview 51.2%

Which one costs less?

Claude Opus 4.8 costs $5 per million input tokens and $25 per million output tokens; Gemini 3 Flash Preview costs $0.50 and $3.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.15 with Claude Opus 4.8 versus $0.016 with Gemini 3 Flash Preview. Gemini 3 Flash Preview is 9.4 times cheaper, a gap that adds up quickly over 1,000 tasks: $134 difference.

Run the numbers with your own volumes in the agent cost calculator.

Context and capabilities

Gemini 3 Flash Preview reads more in one go: 1,048,576 tokens of context (roughly 1,573 pages), versus 1,000,000 for Claude Opus 4.8.

Reasoning mode: Claude Opus 4.8 yes, Gemini 3 Flash Preview yes. Tool calling: Claude Opus 4.8 yes, Gemini 3 Flash Preview yes. Image input: Claude Opus 4.8 yes, Gemini 3 Flash Preview yes.

Neither publishes its weights: both are used through an API.

Knowledge cutoff: January 2026 for Claude Opus 4.8, January 2025 for Gemini 3 Flash Preview.

In short

Our reading of the data:

Choose Claude Opus 4.8 for a higher capability index and a more recent release.
Choose Gemini 3 Flash Preview for a lower cost.

This verdict relies on public figures; it does not replace a trial on your own tasks.

Frequently asked questions

Claude Opus 4.8 or Gemini 3 Flash Preview: which is better?

On our index (Epoch AI data), Claude Opus 4.8 scores 83.4 and Gemini 3 Flash Preview 80.3 out of 100. The best choice also depends on price and on your use case.

Which one is cheaper?

Gemini 3 Flash Preview. To read 20,000 tokens and write 2,000, expect $0.15 with Claude Opus 4.8 and $0.016 with Gemini 3 Flash Preview (prices as of October 22, 2026).

Which one has the larger context window?

Gemini 3 Flash Preview, with 1,048,576 tokens versus 1,000,000.

Can I run Claude Opus 4.8 or Gemini 3 Flash Preview on my own servers?

No: both are closed models, available through an API.

Claude Opus 4.8 or Gemini 3 Flash Preview: which to choose?