Gemini 3.8 Flash vs Gemini 3.5 Flash
Which one to choose
Pick Gemini 3.8 Flash for coding, autonomous agents and enterprise workflows that run for many steps and benefit from thinking before acting. Pick Gemini 3.5 Flash for routine, high-throughput work such as chat, extraction and summarization, where you want a steady general-purpose Flash model. Google describes 3.8 as its most intelligent Flash model and recommends it for new projects, while 3.5 is the baseline for speed and foundational performance.
Pricing comparison
| Gemini 3.8 Flash | Gemini 3.5 Flash | |
|---|---|---|
| Model maker | ||
| Delivery availability | Available | Available |
| Context window | 1M | 1M |
| Max output | 64K | 64K |
| Official price | Input$0.75per 1M tokensOutput$3.75per 1M tokens | Input$1.50per 1M tokensOutput$9.00per 1M tokens |
| TokenLab price | Input$0.375per 1M tokensOutput$1.88per 1M tokens | Input$0.75per 1M tokensOutput$4.50per 1M tokens |
| Model performance |
|
|
| Capabilities | JSON modePrompt CacheTool useVision | JSON modePrompt CacheTool useVision |
Choose Gemini 3.8 Flash when
- You build agents or coding workflows with many dependent steps
- You want a model that plans and debugs with thinking before it acts
- You are starting a new project on the Gemini 3 line
Choose Gemini 3.5 Flash when
- Your traffic is routine chat, extraction or summarization at volume
- Your pipeline is already tuned and stable on Gemini 3.5 Flash
- You do not need thinking for the task
How they differ
| Aspect | Gemini 3.8 Flash | Gemini 3.5 Flash |
|---|---|---|
| Positioning | Google's most intelligent Flash model, recommended for new projects. | Described by Google as the baseline for speed and foundational performance. |
| Thinking | Supports thinking for planning and debugging. | Not marked as a thinking model, so hard multi-step reasoning is better sent elsewhere. |
| Coding and agents | Engineered for long-horizon software engineering and autonomous agents. | Stronger Flash releases after it handle coding and agent tasks better. |
| Enterprise workflows | Aimed at complex workflows with many integrations through tool calling. | Suits assistants that carry a task through a few steps. |
| Shared surface | Text and images in, tool calls, schema-bound JSON and context caching. | The same capabilities, so request shapes carry over. |
Summary
- Gemini 3.8 Flash: Input $0.375 / Output $1.88 per 1M tokens; Gemini 3.5 Flash: Input $0.75 / Output $4.50 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
FAQ
Is Gemini 3.8 Flash better than Gemini 3.5 Flash?
For coding, agents and multi-step work, yes: 3.8 is newer, supports thinking and is the one Google recommends for new projects. For simple high-volume tasks, 3.5 Flash still does the job.
Can I swap Gemini 3.5 Flash for 3.8 Flash without prompt changes?
Usually, since both take text and images, call tools and return schema-bound JSON. Test outputs on your own cases, as the newer model thinks before answering and may respond differently.
Which is better for coding?
Gemini 3.8 Flash. Google positions it for long-horizon software engineering, and it supports thinking and tool calling, which suits plan, edit and test loops in coding agents.
When would I use both?
Use 3.5 Flash for routine, high-volume steps such as extraction and summaries, and 3.8 Flash for the steps that plan, debug or coordinate several tools.
Which is cheaper, Gemini 3.8 Flash or Gemini 3.5 Flash?
Gemini 3.8 Flash: Input $0.375 / Output $1.88 per 1M tokens; Gemini 3.5 Flash: Input $0.75 / Output $4.50 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
What are the key differences between Gemini 3.8 Flash and Gemini 3.5 Flash?
Both models share similar capabilities.
Sources
Reviewed Oct 2, 2026