Gemini 2.5 Flash is the model you reach for when the job runs a million times, not once.
It keeps the thing that made Gemini 2.5 Pro interesting — a 1,048,576-token context window — and gives up deliberation rather than capacity. That is an unusual trade. Most fast models shrink the window; Flash keeps it and shortens the thinking instead.
The number that decides most projects
Flash's knowledge cutoff is January 2025. For a model serving production traffic today, that is a long time ago, and it is the single fact most teams discover too late.
Google's answer is grounding with Google Search, which Flash supports. Turn it on and the model retrieves current information rather than reciting a stale parameter memory. Leave it off and ask about anything recent, and you will get confident, dated answers. Decide this deliberately — it is not a default you want to inherit by accident.
Where the cost actually goes
Across providers Flash lands near $0.30 per million input tokens and $2.50 per million output tokens, though this moves by provider and region and should be confirmed against your own account before you model a budget.
Two features matter more than the headline rate:
- Context caching. If you send the same 200-page contract with every question, caching stops you paying full input price each time. On document-heavy workloads this is usually the largest single saving available.
- Batch API and Flex inference. Work that does not need an answer this second — overnight enrichment, backfills, bulk classification — costs materially less when it is not competing for priority capacity.
Thinking is the lever in the other direction. Flash supports it, and a generous thinking budget erodes exactly the price advantage you chose Flash for.
What it takes in, and what it will not give back
Input is genuinely multimodal: text, images, audio, video and PDFs, with no extraction step in front of the model. A support pipeline can pass a screenshot and a call recording together and ask one question about both.
Output is text. Full stop. Flash does not generate images, does not synthesise speech, and does not support the Live API for real-time bidirectional sessions. If either half of your product needs generated media, that half needs a different model.
Code execution and structured outputs are both supported, so it slots into agent loops and typed pipelines without prompt-engineering the response shape by hand.
When Pro is worth the wait
Flash answers. Pro reasons.
For extraction, routing, classification, tagging and summarisation — tasks with a findable correct answer — Flash is the right call and the latency difference is free money. For work where a wrong answer is expensive and the path to the right one has several steps, Gemini 2.5 Pro earns its slower response.
Specifications
| Field |
Value |
| Provider |
Google |
| Context window |
1,048,576 tokens |
| Maximum output |
65,536 tokens |
| Knowledge cutoff |
January 2025 |
| Input |
text, image, audio, video, PDF |
| Output |
text |
| Thinking |
Supported |
| Function calling |
Supported |
| Structured output |
Supported |
| Context caching |
Supported |
| Code execution |
Supported |
| Search grounding |
Supported |
| Batch API |
Supported |
| Image / audio generation |
Not supported |
| Released |
June 2025 |
Pricing and regional availability move often. Treat the figures above as indicative and confirm them against your own account before you commit to a budget.
Compare Flash against everything else in the AI model directory.