This is a short benchmark note. I tested three Gemini models with three copywriting tasks and recorded only the simple numbers: output tokens, total latency, visible output tokens per second, and API price.

The low-cost model tested here is Gemini 3.1 Flash-Lite with model ID gemini-3.1-flash-lite. The middle model is Gemini 3 Flash Preview with model ID gemini-3-flash-preview. The new model is Gemini 3.5 Flash with model ID gemini-3.5-flash.

Benchmark setup

Setting	Value
Models	`gemini-3.1-flash-lite`, `gemini-3-flash-preview`, `gemini-3.5-flash`
Tasks	3 copywriting tasks
API tier	Gemini Developer API standard tier
Generation config	`temperature: 0.2`, `maxOutputTokens: 700`, `thinkingBudget: 0`
Speed metric	Visible output tokens ÷ end-to-end request latency
Run date	May 19, 2026

Speed results

Bar chart showing Gemini 3.1 Flash-Lite at 156.1 tokens per second, Gemini 3 Flash Preview at 110.7 tokens per second, and Gemini 3.5 Flash at 155.1 tokens per second — Visible output tokens per second across the three copywriting tasks.

Model	Total output tokens	Total latency	Weighted speed	Average latency
`gemini-3.1-flash-lite`	1,040	6.66s	156.1 tok/s	2.22s
`gemini-3-flash-preview`	1,074	9.70s	110.7 tok/s	3.24s
`gemini-3.5-flash`	1,271	8.20s	155.1 tok/s	2.73s

API price

Cost cards showing Gemini 3.1 Flash-Lite at $0.25 input and $1.50 output per million tokens, Gemini 3 Flash Preview at $0.50 input and $3.00 output, and Gemini 3.5 Flash at $1.50 input and $9.00 output — Standard Gemini API token price for the three tested models.

Model	Input price	Output price
`gemini-3.1-flash-lite`	$0.25 / 1M text, image, or video tokens	$1.50 / 1M output tokens
`gemini-3-flash-preview`	$0.50 / 1M text, image, or video tokens	$3.00 / 1M output tokens
`gemini-3.5-flash`	$1.50 / 1M input tokens	$9.00 / 1M output tokens

Speed vs output price

Scatter chart comparing visible output tokens per second against output price per million tokens for Gemini 3.1 Flash-Lite, Gemini 3 Flash Preview, and Gemini 3.5 Flash — Same benchmark data plotted against output token price.

Raw data summary

Fastest in this run: Gemini 3.1 Flash-Lite at 156.1 tok/s.
Very close second: Gemini 3.5 Flash at 155.1 tok/s.
Slowest in this run: Gemini 3 Flash Preview at 110.7 tok/s.
Lowest output price: Gemini 3.1 Flash-Lite at $1.50 / 1M output tokens.
Highest output price: Gemini 3.5 Flash at $9.00 / 1M output tokens.

Gemini 3.5 Flash vs Gemini 3 Flash vs Gemini 3.1 Flash-Lite: speed and cost benchmark

Benchmark setup

Speed results

API price

Speed vs output price

Raw data summary

Sources

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