Gemini 3.1 Pro vs Gemini 2.5 Flash

Gemini 3.1 Pro versus Gemini 2.5 Flash specifications and price.
metric	Gemini 3.1 Pro	Gemini 2.5 Flash
Input / 1M	$2.00	$0.30
Output / 1M	$12.00	$2.50
Context	1.0M	1.0M
Cost @ typical workload	$1,800/mo	$340/mo
Modality	text + image + audio + video	text + image + audio + video
Price source	list	list
Provider	Google	Google

Which should you pick?

On a typical workload, Gemini 2.5 Flash costs $340/mo against Gemini 3.1 Pro's $1,800/mo — roughly 5.3× cheaper. But the ranking depends on your output-to-input ratio: output is the pricier direction for both, so an output-heavy job (code generation, long answers) widens the gap while an input-heavy one (summarization, retrieval) narrows it. Both share the same context window, so that's not a deciding factor here.

These are list and routed market prices, not measured outcomes. Two models at the same rate can still cost different amounts to finish the same task, because verbose or reasoning-heavy models emit more tokens. That gap is exactly what measured cost-per-task captures.

Frequently asked questions

Is Gemini 3.1 Pro or Gemini 2.5 Flash cheaper?

For a typical workload (1,500 input + 500 output tokens × 200,000 requests/month), Gemini 2.5 Flash costs $340/mo versus $1,800/mo for Gemini 3.1 Pro — about 5.3× less. Because output is priced higher than input, the winner can flip if your workload writes much more or less than this; check your own numbers in the calculator.

What's the main difference between Gemini 3.1 Pro and Gemini 2.5 Flash?

On price, Gemini 3.1 Pro is $2.00/$12.00 per 1M (in/out) and Gemini 2.5 Flash is $0.30/$2.50. Both carry the same context window.

More comparisons

Gemini 3.1 Pro and Gemini 2.5 Flash — full specs and price history.
API cost calculator — compare on your own workload.
All comparisons — the full head-to-head index.