Head-to-head
Claude Opus 4.6 vs Gemini 3.5 Flash: which AI model wins in 2026?
Claude Opus 4.6 ($25/1M out) and Gemini 3.5 Flash ($9.00/1M out) are two of the most-used AI models in 2026. Compare them line by line below, then cast your verdict.
Quick verdict
On Reasoning, pick Claude Opus 4.6: the arena rates it 4/5 against 3.5/5 for Gemini 3.5 Flash. On budget, Gemini 3.5 Flash wins: it starts at $9.00/1M out versus $25/1M out for Claude Opus 4.6.
Line-by-line comparison
From
$25/1M outStandard tier $5/$25 per 1M tokens; full 1M context now at standard rates (the launch-time premium of $10/$37.50 above 200K tokens was later dropped), batch API 50% off ($2.50/$12.50), US-only inference (inference_geo) 1.1x multiplier.
$9.00/1M outPaid tier flat rate $1.50/$9.00 per 1M; batch API 50% off ($0.75/$4.50), context caching $0.15/1M plus $1.00/1M per hour storage, free tier available
Provider
Anthropic
Google
Context window
1M tokens (128K max output)
1M tokens (1,048,576 in / 65,536 out)
Input price
$5/1M in
$1.50/1M in
Output price
$25/1M out
$9.00/1M out
Modalities
text, vision (image input), text output
text, vision, audio, video, PDF in; text out
Open weights
No
No
Crowd score
50%(0)
50%(0)
Arena ratings (1-5)
Reasoning
4.0
3.5
Coding
4.0
4.0
Writing
4.0
3.0
Speed
2.5
5.0
Value
3.0
4.5
Strengths and weaknesses
Claude Opus 4.6
- 80.8% SWE-bench Verified (25-trial average) and top Terminal-Bench 2.0 score at launch, the leading agentic coding model of its generation (Feb 2026)
- First Opus with a 1M-token context window: 76% on MRCR v2 8-needle at 1M tokens vs 18.5% for Sonnet 4.5
- Large reasoning jump over Opus 4.5: ARC-AGI-2 68.8% vs 37.6%, +190 Elo on GDPval-AA economic-value tasks (~144 Elo over GPT-5.2)
- Kept Opus 4.5 pricing ($5/$25 per 1M tokens) despite the gains; full 1M context now billed at standard rates, 50% batch discount
- Adaptive thinking plus effort parameter (low/medium/high/max) to trade intelligence, latency and cost per request
- Strong autonomous agent behavior: parallelizes work and needs less handholding than Opus 4.5 (Every.to Vibe Check)
- Slower and more verbose than Opus 4.5; reviewers report the pace 'wavers under load' on long agentic runs (Every.to)
- Writing regressed: in blind tests Every.to's team preferred Opus 4.5's prose, and 4.6 shows more AI-isms like 'X not Y' constructions
- Sometimes makes unexpected changes and 'doesn't always know its own skills', requiring closer supervision than GPT-5.x Codex per reviewers
- Superseded within months by Opus 4.7 and 4.8 at the same $5/$25 price, and fast mode is not available on 4.6 since June 2026 (requests run at standard speed)
- Some devs report benchmark fatigue: day-to-day coding gains over 4.5 are harder to feel than the scores suggest, and SWE-bench itself was flat vs 4.5 (80.8% vs 80.9%)
Gemini 3.5 Flash
- Beats Gemini 3.1 Pro on agentic benchmarks: 76.2% Terminal-Bench 2.1, 1656 Elo GDPval-AA (vs 1314 for 3.1 Pro), 83.6% MCP Atlas
- Artificial Analysis Intelligence Index 50 at high thinking effort, ranking #10 of 170 tracked models
- Very fast generation (~185 output tokens/sec per Artificial Analysis); Google claims 4x faster output than other frontier models
- 1M-token context window (1,048,576) with multimodal input: text, image, audio, video, PDF
- 25% cheaper than Gemini 3.1 Pro ($1.50/$9 vs $2/$12) while outperforming it on production agent workloads
- Adjustable thinking effort (minimal/low/medium/high) plus 50% batch discount and $0.15/1M context caching
- 3x price increase over Gemini 3 Flash ($0.50/$3.00) and 5-6x over 2.5 Flash; HN devs saw it as Google probing price tolerance
- Over-eager and verbose: devs report it ignores completion criteria and embellishes beyond instructions (compared to Claude's 'Sonnet 3.7 moment')
- Reliability complaints on Flash serving: developers report frequent 503 errors during peak periods
- Weaker on long-horizon agentic tasks with arbitrary tool availability, a recurring theme devs report with Google models
- High time-to-first-token (~23s at high thinking effort per Artificial Analysis), poor fit for latency-sensitive chat
Cast your verdict
One recommendation per tool per gladiator. It reshapes the crowd score everyone sees.
Claude Opus 4.6$25/1M out
50%crowd score · 0
Gemini 3.5 Flash$9.00/1M out
50%crowd score · 0
The arena’s verdict on Claude Opus 4.6
A clear upgrade over Opus 4.5 for agentic coding and long-context work at identical pricing, and it held the top agentic coding benchmarks at launch. In mid-2026 however there is little reason to start new projects on it: Opus 4.8 costs the same $5/$25 and outperforms it across the board, so pick 4.6 mainly to pin an already-validated behavior. Writers should avoid it, since blind tests preferred Opus 4.5's prose, and latency-sensitive users should note it is slower than 4.5 with no fast mode option.
The arena’s verdict on Gemini 3.5 Flash
Pick Gemini 3.5 Flash if you run agentic coding or high-volume multimodal pipelines and want near-Pro quality at 4x the speed: it actually beats Gemini 3.1 Pro on Terminal-Bench and GDPval while costing 25% less. Avoid it if you used the Flash line as a budget tier, since it costs 3x its predecessor Gemini 3 Flash, which remains the cheap option at $0.50/$3.00. Also skip it for latency-sensitive chat at high thinking effort (~23s to first token) or strict, no-embellishment output where its verbosity works against you.
Keep comparing
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Frequently asked questions
Is Claude Opus 4.6 better than Gemini 3.5 Flash?
On Reasoning, Claude Opus 4.6 rates higher (4/5 vs 3.5/5). The right pick depends on your use case. The line-by-line comparison on this page breaks down pricing, key specs and arena ratings.
Which is cheaper, Claude Opus 4.6 or Gemini 3.5 Flash?
Gemini 3.5 Flash is cheaper: it starts at $9.00/1M out, while Claude Opus 4.6 starts at $25/1M out.
How much do Claude Opus 4.6 and Gemini 3.5 Flash cost per 1M tokens?
Claude Opus 4.6: $5/1M in per 1M input tokens, $25/1M out per 1M output tokens. Gemini 3.5 Flash: $1.50/1M in per 1M input tokens, $9.00/1M out per 1M output tokens.