Which is cheaper, Gemini 3.8 Flash and GPT-5.5?

Gemini 3.8 Flash has the lowest input price. Per 1M input tokens: Gemini 3.8 Flash from $0.75 and GPT-5.5 from $5.00.

Which has the larger context window, Gemini 3.8 Flash and GPT-5.5?

GPT-5.5 has the largest context window: Gemini 3.8 Flash 1,048,576 tokens and GPT-5.5 1,050,000 tokens.

Which is better for coding, Gemini 3.8 Flash and GPT-5.5?

Gemini 3.8 Flash scores highest on the Artificial Analysis Coding Index: Gemini 3.8 Flash 76.3 and GPT-5.5 74.9.

Can I switch between Gemini 3.8 Flash and GPT-5.5 without changing my code?

Yes. All of them are served through FastRouter's OpenAI-compatible API, so switching is a change of the model parameter (google/gemini-3.8-flash, openai/gpt-5.5).

Gemini 3.8 Flash vs GPT-5.5

Side-by-side pricing per provider, context window, benchmark scores and speed, all on one OpenAI-compatible API.

Gemini 3.8 Flash Googlegoogle/gemini-3.8-flash

GPT-5.5 OpenAIopenai/gpt-5.5

Creator

Google

OpenAI

Released

Sep 2, 2026

Apr 24, 2026

Context window

1.05M

Max output

66K

128K

Input / 1MLowest provider price

$0.75

$5.00$5.00–$5.50 across 2

Output / 1MLowest provider price

$3.75

$30.00$30.00–$33.00 across 2

Providers

IntelligenceArtificial Analysis index

40.9

38.4

CodingArtificial Analysis index

76.3

74.9

LatencyMedian time to first token

—

6.1s

ThroughputMedian tokens per second

—

<1 t/s

Accepts

Text, Image, Audio, Video, Files

Files, Image, Text

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Gemini 3.8 Flash vs GPT-5.5: summary

Gemini 3.8 Flash and GPT-5.5 are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Gemini 3.8 Flash, from Google, has a 1,048,576-token context window, costs from $0.75/1M input and $3.75/1M output tokens across 2 providers and scores 40.9 on the Artificial Analysis Intelligence Index.

GPT-5.5, from OpenAI, has a 1,050,000-token context window, costs from $5.00/1M input and $30.00/1M output tokens across 2 providers and scores 38.4 on the Artificial Analysis Intelligence Index.

Gemini 3.8 Flash is the cheapest on input, 6.7× cheaper than the next model, GPT-5.5 has the largest context window, Gemini 3.8 Flash scores highest for intelligence and Gemini 3.8 Flash leads on coding.

Switch with one line

client = OpenAI(base_url="https://api.fastrouter.ai/api/v1", api_key="<FASTROUTER_API_KEY>") client.chat.completions.create(model="google/gemini-3.8-flash", messages=[...]) # or client.chat.completions.create(model="openai/gpt-5.5", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis