Model comparison
Gemini 3.1 Pro vs Gemini 3.8 Flash
GeminiCompare published specifications, vendor API list prices and measured Borg performance. Both models are included in Borg.
Gemini 3.1 Pro
Gemini 3.8 Flash
Included in Borg
At a glance
| Specification | Gemini 3.1 Pro | Gemini 3.8 Flash |
|---|---|---|
| Provider | ||
| Release | 2026-02-19 Vendor source | 2026-09-02 Vendor source |
| Context | 1,048,576 tokens Vendor source | 1,048,576 tokens Vendor source |
| Modalities | Input: text, image, video, audio, pdf; output: text | Input: text, image, video, audio, pdf; output: text |
| Reasoning / thinking modes | Yes / Not published | Yes / Not published |
| Open weights | No | No |
| Vendor API list price / 1M tokens | $2 input / $12 output Rates for prompts of at most 200,000 tokens; longer prompts cost more. | $0.75 input / $3.75 output Introductory rates through December 31, 2026. From January 1, 2027: $1.50 input / $7.50 output / $0.15 cached input per 1M tokens. |
| Borg | Included in Borg subscription | Included in Borg subscription |
GoogleMeasured on Borg
Metrics are not directly comparable to vendor benchmark claims. Models served different requests; this is observed gateway traffic, not a controlled head-to-head test.
Time to first token (gateway proxy)
No published measurement for this model.
Output tokens per second (whole turn)
No published measurement for this model.
| Metric | Gemini 3.1 Pro | Gemini 3.8 Flash |
|---|---|---|
| Time to first token (gateway proxy) p50 | Not published | 2510 ms (1147 samples) |
| Tokens per second (end to end) p50 | Not published | 29.2 output tokens per second (85551 samples) |
| Request success rate | Not published | Not published |
| Coding bench pass rate | Not published | Not published |
Measurement window, samples and methodology
The fleet reference is the median of published model medians, not a request-weighted result. Prompt lengths, reasoning settings and traffic differ between models.
Gemini 3.1 Pro: Measured on Borg: SearchAtlas AI Gateway production request logs. 30-day window ending 2026-10-08; 278 requests. Minimum 100 samples per published request metric.
Gemini 3.8 Flash: Measured on Borg: SearchAtlas AI Gateway production request logs. 30-day window ending 2026-10-08; 92815 requests. Minimum 100 samples per published request metric.
Completion speed covers the whole turn including queueing and reasoning time; it is not a streaming tokens-per-second figure.
- Time to first token (gateway proxy): time until the first streamed response event reaches the gateway; our closest available measure of time to first token
- Tokens per second (end to end): tokens per second, end to end: provider-reported output tokens divided by the whole turn's elapsed time, including queueing and reasoning; not a streaming per-token rate
How to choose
Gemini 3.1 Pro is listed for complex software engineering, whereas Gemini 3.8 Flash is listed for long-horizon coding agents. Choosing between Gemini 3.1 Pro and Gemini 3.8 Flash requires checking published specifications against observed Borg traffic for your workflow.
Key differences
| Spec | Gemini 3.1 Pro | Gemini 3.8 Flash |
|---|---|---|
| Context window | 1,048,576 tokens Vendor source | 1,048,576 tokens Vendor source |
| Reasoning modes | Yes / Not published | Yes / Not published |
| Release date | 2026-02-19 Vendor source | 2026-09-02 Vendor source |
| API price input / 1M | 2 Rates for prompts of at most 200,000 tokens; longer prompts cost more. | 0.75 Introductory rates through December 31, 2026. From January 1, 2027: $1.50 input / $7.50 output / $0.15 cached input per 1M tokens. Lower listed rate |
| API price output / 1M | 12 Rates for prompts of at most 200,000 tokens; longer prompts cost more. | 3.75 Introductory rates through December 31, 2026. From January 1, 2027: $1.50 input / $7.50 output / $0.15 cached input per 1M tokens. Lower listed rate |
| Time to first token (gateway proxy) | Not published | 2510 ms (1147 samples) |
| Output tokens per second (whole turn) | Not published | 29.2 output tokens/s (whole turn) (85551 samples) |
| Request success | Not published | Not published |
| Coding bench | Not published | Not published |
FAQ
How do Gemini 3.1 Pro and Gemini 3.8 Flash compare for coding?
Gemini 3.1 Pro has a Borg coding benchmark of not published; Gemini 3.8 Flash has not published. The Gemini 3.1 Pro–Gemini 3.8 Flash coding comparison cannot establish an overall winner from this small test alone.
How quickly do Gemini 3.1 Pro and Gemini 3.8 Flash start responding on Borg?
Borg median first response for Gemini 3.1 Pro is not published; for Gemini 3.8 Flash it is 2,510 ms. The Gemini 3.1 Pro–Gemini 3.8 Flash gateway medians are observations, not guaranteed latency for individual requests.
What are the API prices for Gemini 3.1 Pro and Gemini 3.8 Flash?
The listed API rate for Gemini 3.1 Pro is $2 input / $12 output per 1M tokens; for Gemini 3.8 Flash it is $0.75 input / $3.75 output per 1M tokens. Neither Gemini 3.1 Pro nor Gemini 3.8 Flash has its Borg subscription charge represented by those provider API rates. Gemini 3.1 Pro vendor source · Gemini 3.8 Flash vendor source
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