# Gemini 3.5 Flash vs OpenAI GPT-OSS 20B

On provider list prices, OpenAI GPT-OSS 20B costs $0.05 per million input tokens against $1.50 for Gemini 3.5 Flash: 30.0x apart. Output is $0.20 against $9 (45.0x). On Allocate both bill at list plus the 7% transaction fee.

## Specifications

| | Gemini 3.5 Flash | OpenAI GPT-OSS 20B |
| --- | --- | --- |
| Lab | Google | OpenAI |
| Access | API only | Open weights |
| Context window | 1M tokens | 128K tokens |
| List price, input | $1.50 / M tokens | $0.05 / M tokens |
| List price, output | $9 / M tokens | $0.20 / M tokens |
| Cached input | n/a | n/a |
| License | Proprietary API | Apache 2.0 |
| Fine-tunable | No | Yes |

Specifications and provider list prices from the Allocate catalog, checked 2026-07-08. Billed price is list plus the 7% transaction fee.

## What the numbers say

Take 1,000,000 requests a month at 1,200 input and 350 output tokens each. That workload costs $130 a month on OpenAI GPT-OSS 20B and $4,950 on Gemini 3.5 Flash at list: a gap of $4,820, or 38.1x.

Gemini 3.5 Flash reads 1M tokens per request against 128K for OpenAI GPT-OSS 20B, 7.6x the window. That decides which one can take whole documents without splitting them.

## Choose Gemini 3.5 Flash for

- High-volume support and triage
- Document extraction at scale
- Vision and OCR pipelines

## Choose OpenAI GPT-OSS 20B for

- The lower list price ($0.05 in / $0.20 out per M tokens)
- Open weights you can fine-tune and own
- Fine-tuning under a permissive license (Apache 2.0)

## Common questions

### Which is cheaper, Gemini 3.5 Flash or OpenAI GPT-OSS 20B?

OpenAI GPT-OSS 20B, on this workload shape. At list prices it is $0.05/$0.20 per million tokens in and out against $1.50/$9 for Gemini 3.5 Flash. Billed on Allocate: $0.053/$0.21 against $1.60/$9.63, list plus 7%.

### Which has the bigger context window?

Gemini 3.5 Flash: 1,000,000 tokens (1M) against 131,072 (128K) for OpenAI GPT-OSS 20B.

### Can I fine-tune Gemini 3.5 Flash or OpenAI GPT-OSS 20B?

OpenAI GPT-OSS 20B publishes open weights (Apache 2.0) and can be fine-tuned on your own data. Gemini 3.5 Flash is a closed model served over API; its weights are not available.

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[HTML page](https://allocate.network/compare/gemini-3-5-flash-vs-openai-gpt-oss-20b) · [Gemini 3.5 Flash](https://allocate.network/models/gemini-3-5-flash.md) · [OpenAI GPT-OSS 20B](https://allocate.network/models/openai-gpt-oss-20b.md) · [Machine-readable catalog](https://allocate.network/catalog.json)