How much does the Gemini 3.5 Flash API cost?

Gemini 3.5 Flash costs $1.5 per million input tokens and $9 per million output tokens, with cached input at $0.38 per million. A workload of 10M input and 1.5M output tokens per month costs about $28.50.

What is the context window of Gemini 3.5 Flash?

Gemini 3.5 Flash supports a context window of 1,000,000 tokens (1M), with up to 66K output tokens per response.

Is Gemini 3.5 Flash open source?

No — Gemini 3.5 Flash is a proprietary model available through Google's API and partner platforms.

What are the best alternatives to Gemini 3.5 Flash?

The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, GPT-5, OpenAI o3. See the comparison pages for detailed head-to-head breakdowns.

Gemini 3.5 Flash

Name: Gemini 3.5 Flash
Price: 1.5 USD
Author: Google

Google·May 2026reasoningproprietary

Gemini 3.5 Flash, launched at Google I/O 2026, collapsed much of the gap between Google's fast tier and its Pro tier — scoring 78.8% on SWE-bench Verified, within a few points of much pricier flagships. It takes text, images, audio and video natively in a 1M-token context. At $1.50/$9 it sits in an aggressive middle ground: pricier than older Flash models, but far below GPT-5.5 and Opus 4.8 for a large share of their capability.

Benchmark results

SWE-bench VerifiedCoding · #10 of 3378.8%

Where it shines

Flash-tier latency with near-flagship coding quality
Native video and audio understanding
Deep integration with Vertex AI, AI Studio and Workspace

Alternatives to Gemini 3.5 Flash

Qwen3-Max

Alibaba's trillion-parameter API flagship — frontier-adjacent quality with strong agentic tool use at mid-tier prices.

GPT-5.5

OpenAI's flagship reasoning model with a 1M-token context window, built for hard coding, science and long-horizon agentic work.

GPT-5

OpenAI's August 2025 unified flagship that merged the GPT and o-series reasoning lines into one model with selectable effort.

OpenAI o3

OpenAI's dedicated 2025 reasoning model that pioneered thinking-with-images and agentic tool use within chain-of-thought.

Frequently asked questions

How much does the Gemini 3.5 Flash API cost?: Gemini 3.5 Flash costs $1.5 per million input tokens and $9 per million output tokens, with cached input at $0.38 per million. A workload of 10M input and 1.5M output tokens per month costs about $28.50.
What is the context window of Gemini 3.5 Flash?: Gemini 3.5 Flash supports a context window of 1,000,000 tokens (1M), with up to 66K output tokens per response.
Is Gemini 3.5 Flash open source?: No — Gemini 3.5 Flash is a proprietary model available through Google's API and partner platforms.
What are the best alternatives to Gemini 3.5 Flash?: The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, GPT-5, OpenAI o3. See the comparison pages for detailed head-to-head breakdowns.