Choose Google: Gemini 2.5 Pro Preview 05-06 if…
No advantage on the data we track — pick it for provider preference or output quality on your own prompts.
Google: Gemini 2.5 Pro Preview 05-06 vs Google: Gemini 3.8 Flash
Google: Gemini 3.8 Flash comes out ahead on the data we track: 2 advantages and none for Google: Gemini 2.5 Pro Preview 05-06.
Key numbers
| Spec | Google: Gemini 2.5 Pro Preview 05-06 | Google: Gemini 3.8 Flash |
|---|---|---|
| Provider | ||
| Input price (per 1M tokens) | $1.25 | $0.82 |
| Output price (per 1M tokens) | $10.00 | $4.13 |
| Blended price (3:1 input/output) | $3.44 | $1.65 |
| Cheaper than … of all models we track | 18% | 30% |
| Context window | 1.0M tokens (~1,573 pages) | 1.0M tokens (~1,573 pages) |
| Larger context than … of all models | 80% | 80% |
| Max output per response | 66K tokens (~49,200 words) | 66K tokens (~49,200 words) |
| Input types | text, image, file, audio, video | text, image, video, file, audio |
| Output types | text | text |
| Free variant | No | No |
| Listed since | 2025-05-07 | 2026-09-02 |
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What it costs for real workloads
Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
| Workload (per month) | Google: Gemini 2.5 Pro Preview 05-06 | Google: Gemini 3.8 Flash | Difference |
|---|---|---|---|
| Customer-support chatbot 50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens) | $294 | $144 | Google: Gemini 3.8 Flash saves $149 |
| RAG search over documents 20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens) | $250 | $140 | Google: Gemini 3.8 Flash saves $110 |
| Coding / tool-using agent 2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens) | $270 | $149 | Google: Gemini 3.8 Flash saves $122 |
| Batch summarisation 10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens) | $160 | $90.75 | Google: Gemini 3.8 Flash saves $69.25 |
| Long-document analysis 500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens) | $72.50 | $45.38 | Google: Gemini 3.8 Flash saves $27.13 |
Capabilities side by side
| Capability | Google: Gemini 2.5 Pro Preview 05-06 | Google: Gemini 3.8 Flash | What it lets you do |
|---|---|---|---|
| Tool / function calling | ✓ Yes | ✓ Yes | call your APIs and run agent loops |
| Structured output (JSON schema) | ✓ Yes | ✓ Yes | return JSON that validates against your schema |
| Reasoning / thinking mode | ✓ Yes | ✓ Yes | spend extra tokens thinking before answering hard problems |
| Image input | ✓ Yes | ✓ Yes | read screenshots, charts and scanned pages |
| Audio input | ✓ Yes | ✓ Yes | take speech or audio directly |
| File / PDF input | ✓ Yes | ✓ Yes | accept documents without your own parsing step |
| Image output | — | — | generate images, not just text |
| Built-in web search | ✓ Yes | ✓ Yes | answer from live web results |
| Seed (reproducible sampling) | ✓ Yes | ✓ Yes | repeat a generation for tests and evals |
| Log-probabilities | — | — | read token confidence for classification and scoring |
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Price history
- Google: Gemini 2.5 Pro Preview 05-06: price unchanged since we started tracking it on 2026-03-10.
- Google: Gemini 3.8 Flash: input price raised 9% ($0.75 → $0.82/1M), output price raised 9% ($3.75 → $4.13/1M) on 2026-10-16.
| Date | Model | Input / 1M | Output / 1M |
|---|---|---|---|
| 2026-10-16 | Google: Gemini 3.8 Flash | $0.82 | $4.13 |
Which should you choose?
Choose Google: Gemini 3.8 Flash if…
- cost matters at scale — it is 52% cheaper on a typical 3:1 input/output mix ($144 vs $294 a month for 50,000 support chats)
- you want the newer model — released 2026-09-02, 16 months after the other
Frequently asked questions
Is Google: Gemini 2.5 Pro Preview 05-06 better than Google: Gemini 3.8 Flash?
Google: Gemini 3.8 Flash comes out ahead on the data we track: 2 advantages and none for Google: Gemini 2.5 Pro Preview 05-06.
Which is cheaper, Google: Gemini 2.5 Pro Preview 05-06 or Google: Gemini 3.8 Flash?
Google: Gemini 3.8 Flash is cheaper: $1.65 vs $3.44 per 1M tokens at a typical 3:1 input/output mix, 52% less. For 50,000 support conversations a month that is $144 against $294.
How much do Google: Gemini 2.5 Pro Preview 05-06 and Google: Gemini 3.8 Flash cost per million tokens?
Google: Gemini 2.5 Pro Preview 05-06 costs $1.25 per 1M input tokens and $10.00 per 1M output tokens; Google: Gemini 3.8 Flash costs $0.82 input and $4.13 output. Output tokens are billed separately, so long answers shift the gap.
Which has the bigger context window, Google: Gemini 2.5 Pro Preview 05-06 or Google: Gemini 3.8 Flash?
Both take 1.0M tokens per request — roughly 1,573 pages of text.
Do Google: Gemini 2.5 Pro Preview 05-06 and Google: Gemini 3.8 Flash support function calling and JSON output?
Tool calling — Google: Gemini 2.5 Pro Preview 05-06: yes, Google: Gemini 3.8 Flash: yes. JSON-schema structured output — Google: Gemini 2.5 Pro Preview 05-06: yes, Google: Gemini 3.8 Flash: yes.
Can Google: Gemini 2.5 Pro Preview 05-06 or Google: Gemini 3.8 Flash read images?
Yes, both accept image input.
Is Google: Gemini 2.5 Pro Preview 05-06 or Google: Gemini 3.8 Flash free to use?
No free variant is listed for either; both are pay-per-token.
What is the maximum output length of Google: Gemini 2.5 Pro Preview 05-06 and Google: Gemini 3.8 Flash?
Google: Gemini 2.5 Pro Preview 05-06 can write up to 66K tokens (about 49,200 words) per response; Google: Gemini 3.8 Flash up to 66K (about 49,200 words).
When were Google: Gemini 2.5 Pro Preview 05-06 and Google: Gemini 3.8 Flash released?
Google: Gemini 2.5 Pro Preview 05-06 was listed on 2025-05-07; Google: Gemini 3.8 Flash on 2026-09-02.
Has the price of Google: Gemini 2.5 Pro Preview 05-06 or Google: Gemini 3.8 Flash changed?
Google: Gemini 2.5 Pro Preview 05-06: price unchanged since we started tracking it on 2026-03-10. Google: Gemini 3.8 Flash: input price raised 9% ($0.75 → $0.82/1M), output price raised 9% ($3.75 → $4.13/1M) on 2026-10-16.
About the two models
Google: Gemini 2.5 Pro Preview 05-06
Gemini 2.5 Pro is Google’s state-of-the-art AI model designed for advanced reasoning, coding, mathematics, and scientific tasks. It employs “thinking” capabilities, enabling it to reason through responses with enhanced accuracy...
Full Google: Gemini 2.5 Pro Preview 05-06 specs →Google: Gemini 3.8 Flash
Gemini 3.8 Flash is Google's most intelligent Flash model with significant gains from 3.7 Flash across software engineering, agentic tasks, and multi-step reasoning.
Full Google: Gemini 3.8 Flash specs →