Standard Compute
Model Comparison 2026

Gemini 3.1 Pro vs Gemini 3.5 Flash

Gemini 3.1 Pro
Google · Frontier · Proprietary
$5.00/1M · 1.0M ctx
Gemini 3.5 Flash
Google · Balanced · Proprietary
$3.75/1M · 1.0M ctx

Community Vote

Pick a winner in each dimension — change your vote anytime.

Output Quality
Correctness and depth of what it produces
Agentic Ability
Tool calls, instruction-following, and multi-step tasks
Speed
Tokens per second and time-to-first-token
Value for $
How much capability you get per dollar
Reliability
Consistent results — fewer refusals, loops, and format breaks

Specs & Pricing, Side by Side

Spec
Gemini 3.1 Pro
Gemini 3.5 Flash
Maker
Google
Google
Blended price / 1M
$5.00
$3.75
Input / output
$2.00 in · $12 out / 1M tokens
$1.50 in · $9.00 out / 1M tokens
Context window
1.0M
1.0M
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
9.2
8.9
Agentic Ability
9.0
8.9
Speed
7.5
9.4
Value for $
8.1
8.7
Reliability
8.8
8.9

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Gemini 3.1 Pro or Gemini 3.5 Flash?

Updated 2026-08-02

Choose Gemini 3.1 Pro if you want huge-context and multimodal work, and Gemini CLI users. Choose Gemini 3.5 Flash if you want high-throughput agents that need big context cheaply.

In our editorial scoring, Gemini 3.5 Flash leads in 3 of five dimensions (speed, value for $ and reliability), while Gemini 3.1 Pro leads in 2. On price, Gemini 3.1 Pro runs about $5.00 per 1M tokens (blended) and is proprietary; Gemini 3.5 Flash is about $3.75 and proprietary.

Where Gemini 3.1 Pro falls short
  • Tool use a touch behind Claude/GPT on some agents
  • Preview-tier stability varies
Full Gemini 3.1 Pro breakdown →
Where Gemini 3.5 Flash falls short
  • Below Pro on hard reasoning
  • Occasional verbosity
Full Gemini 3.5 Flash breakdown →

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